1.
Laminated glass
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Laminated glass is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral or ethylene-vinyl acetate, the interlayer keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a characteristic spider web cracking pattern when the impact is not enough to pierce the glass. In the case of the EVA, the thermoset EVA, offers a complete bounding with the material whether it is glass, polycarbonate, PET, or other types products. Laminated glass is used when there is a possibility of human impact or where the glass could fall if shattered. Skylight glazing and automobile windshields typically use laminated glass, in geographical areas requiring hurricane-resistant construction, laminated glass is often used in exterior storefronts, curtain walls and windows. Laminated glass is used to increase the sound insulation rating of a window. For this purpose a special acoustic PVB compound is used for the interlayer, in the case of the EVA material, no additional acoustic material is required, since the EVA provides sound insulation. An additional property of laminated glass for windows is that a PVB, a thermoset EVA could block up to 99. 9% of the UV rays. In 1902, the French Le Carbone corporation obtained a patent for coating glass objects with celluloid in order to render them susceptible to cracking or breaking. Laminated glass was invented in 1903 by the French chemist Édouard Bénédictus, a glass flask had become coated with the plastic cellulose nitrate and when dropped shattered but did not break into pieces. However, it was not until 1909 that Benedictus filed a patent, in 1911, he formed the Société du Verre Triplex, which fabricated a glass-plastic composite to reduce injuries in car accidents. Production of Triplex glass was slow and painstaking, making it expensive and it was not immediately widely adopted by automobile manufacturers, but laminated glass was widely used in the eyepieces of gas masks during World War I. In 1912, the process was licensed to The English Triplex Safety Glass Company, subsequently, in the United States, both Libbey Owens-Ford and Du Pont de Nemours with Pittsburg Plate Glass produced Triplex. Meanwhile, in 1905, John Crewe Wood, a solicitor in Swindon, Wiltshire, England, the layers of glass were bonded together by Canada balsam. In 1906 he founded the Safety Motor Screen Co. to produce, in 1927, the Canadian chemists Howard W. Matheson and Frederick W. Skirrow invented the plastic polyvinyl butyral. Within five years, the new safety glass had replaced its predecessor. In the Road Traffic Act of 1930, the British parliament required new cars to use windscreens of safety glass
2.
Methylenedioxymethamphetamine
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3, 4-Methylenedioxymethamphetamine, commonly known as ecstasy, is a psychoactive drug used primarily as a recreational drug. Desired effects include increased empathy, euphoria, and heightened sensations, when taken by mouth, effects begin after 30–45 minutes and last 3–6 hours. It is also sometimes snorted or smoked, as of 2017, MDMA has no accepted medical uses. Adverse effects of MDMA use include addiction, memory problems, paranoia, difficulty sleeping, teeth grinding, blurred vision, sweating, use may also lead to depression and fatigue. Deaths have been reported due to increased temperature and dehydration. MDMA increases the release and slows the reuptake of the serotonin, dopamine. It has stimulant and psychedelic effects, the initial increase is followed by a short-term decrease in the neurotransmitters. MDMA belongs to the substituted methylenedioxyphenethylamine and substituted amphetamine classes of drugs, MDMA was first made in 1912. It was used to improve psychotherapy beginning in the 1970s and became popular as a drug in the 1980s. MDMA is commonly associated with parties, raves, and electronic dance music. It is often mixed with other substances such as ephedrine, amphetamine. In 2014, between 9 and 29 million people between the ages of 15 and 64 used ecstasy and this was broadly similar to the percentage of people who use cocaine, amphetamines, and opioids, but fewer than for cannabis. In the United States, about 0.9 million people used ecstasy in 2010, MDMA is generally illegal in most countries. Limited exceptions are made for research. Researchers are investigating whether a few low doses of MDMA may assist in treating severe, in November 2016, phase 3 clinical trials for PTSD were approved by the United States Food and Drug Administration to assess effectiveness and safety. As of 2017, MDMA has no accepted medical indications, before it was widely banned, it saw limited use in therapy. A small number of therapists continue to use MDMA in therapy despite its illegal status, MDMA is often considered the drug of choice within the rave culture and is also used at clubs, festivals and house parties. In the rave environment, the effects from the music
3.
Para-Methoxy-N-methylamphetamine
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PMMA is the 4-methoxy analog of methamphetamine. In the early 2010s, a number of deaths in users of the drug MDMA were linked to misrepresented tablets and its effects in humans are reputedly similar to those of PMA, but slightly more empathogenic in nature. It has a tendency to produce severe hyperthermia at low dosages. Shulgin reported that PMMA produces an increase in pressure and in heart rate, at doses above 100 mg. PMMA has been found in tablets and capsules of the MDMA sold as ecstasy, a number of deaths have been attributed to tablets sold as ecstasy that contained other substances, such as PMMAs structural analog, PMA. Death can occur when a user believes they are consuming recreational doses of MDMA. PMMA can be detected with pill testing kits, in January 2011, the Norwegian Broadcasting Corporation reported that Norway had seen 12 deaths related to PMMA over the course of 6 months. In March 2011, Dutch media reported that there had been 4 deaths in the province of Limburg since November 2010, in April 2011, Icelandic media reported the death of a young woman that may have been connected to PMMA. In 2011,4 deaths were recorded in Scotland as a result of ecstasy tablets which also contained PMMA, in January 2012, a number of ecstasy-related deaths in Canada in the previous year were linked to PMMA overdoses. In September 2012, the deaths of two men in County Cork, Ireland, have linked to PMMA overdoses. In the same month, the death of a man in Queensland, in December 2012 and January 2013, several deaths were linked to PMMA in the UK. In June 2013 a PMMA-related death occurred in the Dutch city of s-Hertogenbosch, two months later, In August 2013, another possibly PMMA-related death occurred in the nearby town of Sliedrecht. In January 2015 in the UK four people died, suspected of taking ecstasy containing PMMA, in the same month, in Sweden, another man died from ecstasy laced with PMMA. In May 2015 a young woman died in Dublin, Ireland, in April 2016 four young Argentines and one Uruguayan died during a massive rave called Time Warp in Buenos Aires and five more were hospitalized. PMMA was found in their bodies, PMMA is a Schedule I controlled substance in the state of Florida, listed as 4-methoxymethamphetamine, making it illegal to buy, sell, or possess in Florida. PMMA is controlled as a Schedule 1, Class A drug in the UK
4.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
5.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses
6.
European Chemicals Agency
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ECHA is the driving force among regulatory authorities in implementing the EUs chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and it is located in Helsinki, Finland. The Agency, headed by Executive Director Geert Dancet, started working on 1 June 2007, the REACH Regulation requires companies to provide information on the hazards, risks and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most commonly used substances have been registered, the information is technical but gives detail on the impact of each chemical on people and the environment. This also gives European consumers the right to ask whether the goods they buy contain dangerous substances. The Classification, Labelling and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU. This worldwide system makes it easier for workers and consumers to know the effects of chemicals, companies need to notify ECHA of the classification and labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100000 substances, the information is freely available on their website. Consumers can check chemicals in the products they use, Biocidal products include, for example, insect repellents and disinfectants used in hospitals. The Biocidal Products Regulation ensures that there is information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation, the law on Prior Informed Consent sets guidelines for the export and import of hazardous chemicals. Through this mechanism, countries due to hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have effects on human health and the environment are identified as Substances of Very High Concern 1. These are mainly substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment, other substances considered as SVHCs include, for example, endocrine disrupting chemicals. Companies manufacturing or importing articles containing these substances in a concentration above 0 and they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy, once a substance has been officially identified in the EU as being of very high concern, it will be added to a list. This list is available on ECHA’s website and shows consumers and industry which chemicals are identified as SVHCs, Substances placed on the Candidate List can then move to another list
7.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES
8.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
9.
Carbon
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Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
10.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
11.
Hydrogen
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Hydrogen is a chemical element with chemical symbol H and atomic number 1. With a standard weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form is the most abundant chemical substance in the Universe, non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium, has one proton, the universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays an important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a charge when it is known as a hydride. The hydrogen cation is written as though composed of a bare proton, Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. Industrial production is mainly from steam reforming natural gas, and less often from more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production, mostly for the fertilizer market, Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks. Hydrogen gas is flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion is −286 kJ/mol,2 H2 + O2 →2 H2O +572 kJ Hydrogen gas forms explosive mixtures with air in concentrations from 4–74%, the explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C, the detection of a burning hydrogen leak may require a flame detector, such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames, the destruction of the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated. The visible orange flames in that incident were the result of a mixture of hydrogen to oxygen combined with carbon compounds from the airship skin. H2 reacts with every oxidizing element, the ground state energy level of the electron in a hydrogen atom is −13.6 eV, which is equivalent to an ultraviolet photon of roughly 91 nm wavelength. The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, however, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objects are held by gravity. The most complicated treatments allow for the effects of special relativity
12.
Density
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity, osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume. As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
13.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
14.
Refractive index
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In optics, the refractive index or index of refraction n of a material is a dimensionless number that describes how light propagates through that medium. It is defined as n = c v, where c is the speed of light in vacuum, for example, the refractive index of water is 1.333, meaning that light travels 1.333 times faster in a vacuum than it does in water. The refractive index determines how light is bent, or refracted. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the angle for total internal reflection. This implies that vacuum has a index of 1. The refractive index varies with the wavelength of light and this is called dispersion and causes the splitting of white light into its constituent colors in prisms and rainbows, and chromatic aberration in lenses. Light propagation in absorbing materials can be described using a refractive index. The imaginary part then handles the attenuation, while the real part accounts for refraction, the concept of refractive index is widely used within the full electromagnetic spectrum, from X-rays to radio waves. It can also be used with wave phenomena such as sound, in this case the speed of sound is used instead of that of light and a reference medium other than vacuum must be chosen. Thomas Young was presumably the person who first used, and invented, at the same time he changed this value of refractive power into a single number, instead of the traditional ratio of two numbers. The ratio had the disadvantage of different appearances, newton, who called it the proportion of the sines of incidence and refraction, wrote it as a ratio of two numbers, like 529 to 396. Hauksbee, who called it the ratio of refraction, wrote it as a ratio with a fixed numerator, hutton wrote it as a ratio with a fixed denominator, like 1.3358 to 1. Young did not use a symbol for the index of refraction, in the next years, others started using different symbols, n, m, and µ. For visible light most transparent media have refractive indices between 1 and 2, a few examples are given in the adjacent table. These values are measured at the yellow doublet D-line of sodium, with a wavelength of 589 nanometers, gases at atmospheric pressure have refractive indices close to 1 because of their low density. Almost all solids and liquids have refractive indices above 1.3, aerogel is a very low density solid that can be produced with refractive index in the range from 1.002 to 1.265. Moissanite lies at the end of the range with a refractive index as high as 2.65. Most plastics have refractive indices in the range from 1.3 to 1.7, for infrared light refractive indices can be considerably higher
15.
Lichtenberg figure
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Lichtenberg figures, or Lichtenberg dust figures, are branching electric discharges that sometimes appear on the surface or in the interior of insulating materials. Lichtenberg figures are associated with the progressive deterioration of high voltage components. Lichtenberg figures are now known to occur on or within solids, liquids, Lichtenberg figures are named after the German physicist Georg Christoph Lichtenberg, who originally discovered and studied them. When they were first discovered, it was thought that their characteristic shapes might help to reveal the nature of positive and negative electric fluids, in 1777, Lichtenberg built a large electrophorus to generate high voltage static electricity through induction. After discharging a high point to the surface of an insulator. By then pressing blank sheets of paper onto these patterns, Lichtenberg was able to transfer and record these images and this discovery was also the forerunner of the modern day science of plasma physics. Although Lichtenberg only studied two-dimensional figures, modern high voltage researchers study 2D and 3D figures on, Lichtenberg figures are now known to be examples of fractals. Two-dimensional Lichtenberg figures can be produced by placing a sharp-pointed needle perpendicular to the surface of a plate, such as of resin, ebonite. The point is positioned very near or contacting the plate, a source of high voltage, such as a Leyden jar or a static electricity generator, is applied to the needle, typically through a spark gap. This creates a sudden, small electrical discharge along the surface of the plate and this deposits stranded areas of charge onto the surface of the plate. These electrified areas are then tested by sprinkling a mixture of powdered flowers of sulfur, during handling, powdered sulfur tends to acquire a slight negative charge, while red lead tends to acquire a slight positive charge. The negatively electrified sulfur is attracted to the positively electrified areas of the plate, if the charge areas were positive, a widely extending patch is seen on the plate, consisting of a dense nucleus, from which branches radiate in all directions. Negatively charged areas are smaller and have a sharp circular or fan-like boundary entirely devoid of branches. Heinrich Rudolf Hertz employed Lichtenberg dust figures in his seminal work proving Maxwells electromagnetic wave theories, the difference between positive and negative figures seems to depend on the presence of air, for the difference tends to disappear when the experiment is conducted in vacuum. This electrification would favor the spread of a positive, but hinder that of a negative discharge and it is now known that electrical charges are transferred to the insulators surface through small spark discharges that occur along the boundary between the gas and insulator surface. Once transferred to the insulator, these excess charges become temporarily stranded, the shapes of the resulting charge distributions reflect the shape of the spark discharges which, in turn, depend on the high voltage polarity and pressure of the gas. Using a higher applied voltage will generate larger diameter and more branched figures and it is now known that positive Lichtenberg figures have longer, branching structures because long sparks within air can more easily form and propagate from positively charged high voltage terminals. This property has been used to measure the transient voltage polarity, another type of 2D Lichtenberg figure can be created when an insulating surface becomes contaminated with semiconducting material
16.
Transparency and translucency
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In the field of optics, transparency is the physical property of allowing light to pass through the material without being scattered. On a macroscopic scale, the photons can be said to follow Snells Law, in other words, a translucent medium allows the transport of light while a transparent medium not only allows the transport of light but allows for image formation. The opposite property of translucency is opacity, transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. When light encounters a material, it can interact with it in different ways. These interactions depend on the wavelength of the light and the nature of the material, photons interact with an object by some combination of reflection, absorption and transmission. Some materials, such as glass and clean water, transmit much of the light that falls on them and reflect little of it. Many liquids and aqueous solutions are highly transparent, absence of structural defects and molecular structure of most liquids are mostly responsible for excellent optical transmission. Materials which do not transmit light are called opaque, many such substances have a chemical composition which includes what are referred to as absorption centers. Many substances are selective in their absorption of light frequencies. They absorb certain portions of the spectrum while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation and this is what gives rise to color. The attenuation of light of all frequencies and wavelengths is due to the mechanisms of absorption. Transparency can provide almost perfect camouflage for animals able to achieve it and this is easier in dimly-lit or turbid seawater than in good illumination. Many marine animals such as jellyfish are highly transparent, at the atomic or molecular level, physical absorption in the infrared portion of the spectrum depends on the frequencies of atomic or molecular vibrations or chemical bonds, and on selection rules. Nitrogen and oxygen are not greenhouse gases because there is no absorption because there is no molecular dipole moment. With regard to the scattering of light, the most critical factor is the scale of any or all of these structural features relative to the wavelength of the light being scattered. Primary material considerations include, Crystalline structure, whether or not the atoms or molecules exhibit the long-range order evidenced in crystalline solids, glassy structure, scattering centers include fluctuations in density or composition. Microstructure, scattering centers include internal surfaces such as boundaries, crystallographic defects
17.
Thermoplastic
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A thermoplastic, or thermosoftening plastic, is a plastic material, a polymer, that becomes pliable or moldable above a specific temperature and solidifies upon cooling. Most thermoplastics have a molecular weight. The polymer chains associate through intermolecular forces, which weaken rapidly with increased temperature, thermoplastics differ from thermosetting polymers, which form irreversible chemical bonds during the curing process. Thermosets do not melt, but decompose and do not reform upon cooling, above its glass transition temperature and below its melting point, the physical properties of a thermoplastic change drastically without an associated phase change. Some thermoplastics do not fully crystallize below the transition temperature. Amorphous and semi-amorphous plastics are used when high optical clarity is necessary, amorphous and semi-amorphous plastics are less resistant to chemical attack and environmental stress cracking because they lack a crystalline structure. Brittleness can be decreased with the addition of plasticizers, which increases the mobility of amorphous chain segments to effectively lowers the transition temperature. Modification of the polymer through copolymerization or through the addition of side chains to monomers before polymerization can also lower it. Naval Research Laboratory developed thermoplastic armor, that can be repaired in the field by a user via tools for pressing irons, acrylic, a polymer called poly, is also known by trade names such as Lucite, Perspex and Plexiglas. It serves as a substitute for glass for items such as aquariums, motorcycle helmet visors, aircraft windows, viewing ports of submersibles. It is extensively used to make signs, including lettering and logos, in medicine, it is used in bone cement and to replace eye lenses. Acrylic paint consists of PMMA particles suspended in water, acrylonitrile butadiene styrene is a terpolymer synthesized from styrene and acrylonitrile in the presence of polybutadiene. ABS is a material that exhibits high impact resistance and mechanical toughness. It poses few risks to health under normal handling. It is used in consumer products, such as toys, appliances. Nylon belongs to a class of polymers called polyamides and it has served as a substitute mainly for hemp, cotton and silk, in products such as parachutes, cords, sails, flak vests and womens clothing. Nylon fibers are useful in making fabrics, rope, carpets and musical strings, whereas in bulk form, Nylon is used for mechanical parts including machine screws, gears, in addition, it is used in the manufacture of heat-resistant composite materials. Polylactic acid is a biodegradable thermoplastic aliphatic polyester derived from renewable resources, such as starch, tapioca roots, chips or starch
18.
Soda-lime glass
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Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of glass, used for windowpanes and glass containers for beverages, food, and some commodity items. Glass bakeware is often made of tempered soda-lime glass, soda-lime glass accounts for about 90% of manufactured glass. Soda-lime glass is relatively inexpensive, chemically stable, reasonably hard, because it can be resoftened and remelted numerous times, it is ideal for glass recycling. The temperature is limited by the quality of the furnace superstructure material. Relatively inexpensive minerals such as trona, sand, and feldspar are usually used instead of pure chemicals, green and brown bottles are obtained from raw materials containing iron oxide. The mix of raw materials is termed batch, soda-lime glass is divided technically into glass used for windows, called flat glass, and glass for containers, called container glass. The two types differ in the application, production method, and chemical composition, flat glass has a higher magnesium oxide and sodium oxide content than container glass, and a lower silica, calcium oxide, and aluminium oxide content. From the lower content of highly water-soluble ions in container glass comes its slightly higher chemical durability against water, the following table lists some physical properties of soda-lime glasses. Unless otherwise stated, the compositions and many experimentally determined properties are taken from one large study. Those values marked in italic font have been interpolated from similar glass compositions due to the lack of experimental data. Coefficient of restitution,0.97 ±0.01 Thermal conductivity,0. 7-1.3 W/m. K Hardness,6 Knoop hardness,585 kg/mm2 +20 Glass batch calculation
19.
Glass
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Glass is a non-crystalline amorphous solid that is often transparent and has widespread practical, technological, and decorative usage in, for example, window panes, tableware, and optoelectronics. The most familiar, and historically the oldest, types of glass are silicate glasses based on the chemical compound silica, the primary constituent of sand. The term glass, in usage, is often used to refer only to this type of material. Many applications of silicate glasses derive from their optical transparency, giving rise to their use as window panes. Glass can be coloured by adding metallic salts, and can also be painted and printed with vitreous enamels and these qualities have led to the extensive use of glass in the manufacture of art objects and in particular, stained glass windows. Although brittle, silicate glass is extremely durable, and many examples of glass fragments exist from early glass-making cultures, because glass can be formed or moulded into any shape, it has been traditionally used for vessels, bowls, vases, bottles, jars and drinking glasses. In its most solid forms it has also used for paperweights, marbles. Some objects historically were so commonly made of glass that they are simply called by the name of the material, such as drinking glasses. Porcelains and many polymer thermoplastics familiar from everyday use are glasses and these sorts of glasses can be made of quite different kinds of materials than silica, metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications, like glass bottles or eyewear, polymer glasses are a lighter alternative than traditional glass, silica is a common fundamental constituent of glass. In nature, vitrification of quartz occurs when lightning strikes sand, forming hollow, fused quartz is a glass made from chemically-pure SiO2. It has excellent resistance to shock, being able to survive immersion in water while red hot. However, its high melting-temperature and viscosity make it difficult to work with, normally, other substances are added to simplify processing. One is sodium carbonate, which lowers the transition temperature. The soda makes the glass water-soluble, which is undesirable, so lime, some magnesium oxide. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass, soda-lime glasses account for about 90% of manufactured glass. Most common glass contains other ingredients to change its properties, lead glass or flint glass is more brilliant because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index, iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium oxide can be used for glass that absorbs UV wavelengths
20.
Methyl methacrylate
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Methyl methacrylate is an organic compound with the formula CH2=CCOOCH3. This colourless liquid, the ester of methacrylic acid is a monomer produced on a large scale for the production of poly. The compound is manufactured by methods, the principal one being the acetone cyanohydrin route. ACH is produced by condensation of acetone and hydrogen cyanide, the cyanohydrin is hydrolyzed in the presence of sulfuric acid to a sulfate ester of the methacrylamide, Methanolysis of this ester gives ammonium bisulfate and MMA. Although widely used, the ACH route coproduces substantial amounts of ammonium sulfate, 2CO + HCN → 2CCN 2CCN + H2SO4 → 2CCNH2. In fact the sulfate ester of the amide is produced as an adduct with sulfuric acid. This technology affords more than 3 billion kilograms per year, the economics of the ACH route have been heavily optimized. Given the scale of production, many methods have been developed starting from diverse two- to four-carbon precursors, ethylene is first hydroformylated to give propanal, which is then condensed with formaldehyde to produce methacrolein, The condensation is catalyzed by a secondary amine. This catalyst, caesium oxide on silica, achieves good selectivity to MMA from MeP, the formation of a small amount of heavy, relatively involatile compounds poisons the catalyst. The coke is easily removed and catalyst activity and selectivity restored by controlled, the reactor product stream is separated in a primary distillation so that a crude MMA product stream, free from water, MeP and formaldehyde, is produced. Unreacted MeP and water are recycled via the dehydration process. Pure MMA is produced from the crude MMA in a series of vacuum distillations and separations, in all cases, the separated streams are returned to the process, there is only one heavy ester purge stream. This is readily disposed of in an oxidizer with heat recovered for use in the process. In the fourth quarter of 2008, Lucite international commissioned its ‘first in class’ Alpha MMA plant based on Jurong Island in Singapore and this process plant is 30-40% cheaper to build and run than conventional systems, produces virtually no waste and the feedstocks can even be made from biomass. Metal oxides catalyse this process, 2CHCO2H + O → CH2=CCO2H + H2O Using Reppe chemistry, cH2=C–2 + O2 → CH2=C–CHO + H2O CH2=C–CHO + 1⁄2 O2 → CH2=C–COOH CH2=C–COOH + CH3OH → CH2=C–COOCH3 + H2O MAN can be produced by ammoxidation from isobutylene. This step is analogous to the route to acrylonitrile, a related commodity chemical. The raw material is tert-butanol, as in the direct oxidation method, CH2=C–CHO + CH3OH + 1⁄2 O2 → CH2=C–COOCH3 + H2O A process using isobutylene as a raw material has been commercially employed by Escambia Co. for a short period of time. Isobutylene is oxidized to provide α-hydroxy isobutyric acid by using N2O4, after esterification and dehydration MMA is obtained
21.
Rohm and Haas
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Rohm and Haas Company is a manufacturer of speciality chemicals for end use markets such as building and construction, electronic devices, packaging, household and personal care products. Formerly a Fortune 500 Company, Rohm and Haas employs more than 17,000 people in 27 countries, Dow Chemical Company bought Rohm and Haas for $15 billion in 2009. The company was founded in Esslingen, Germany, by Dr. Otto Röhm, the company again grew rapidly as World War II approached, as it manufactured Plexiglas acrylic, a transparent plastic which was needed for aircraft canopies. They sold this part of the business in 1998 to Elf Atochem, in 1965 Rohm and Haas moved its headquarters from its Washington Square to a new building on Independence Mall a few blocks away. The new Rohm and Haas Corporate Headquarters was designed by Pietro Belluschi, in 1999 Rohm and Haas acquired the Morton Salt company. On July 10,2008 Rohm and Haas announced it was being bought by Dow Chemical Company for US$18.8 billion, Rohm and Haas will continue doing business under its name and will remain in its Philadelphia headquarters. Dow Chemical tried to out of acquiring Rohm and Haas. On 2 April 2009, it was reported that Morton Salt was being acquired by German fertilizer, the sale, completed by October 2009, was in conjunction with the Dow Chemical Companys takeover of Rohm and Haas. Dow announced their intent to sell the Rohm and Haas Powder Division, on July 6,2004, the Environmental Protection Agency charged Rohm and Haas with violating the Clean Air Act after inspecting its facility in Louisville, Kentucky. On February 12,2006, eleven workers were hospitalized after being exposed to fumes that leaked out of the Rohm and Haas Corporation chemical plant in Cincinnati, Ohio. On February 15,2006, an employee died when working on a steam ejector due to the inhalation of hydrogen sulfide gas, an investigation determined that since the sewer vent was plugged, the hydrogen sulfide gas accumulated into large concentrations that became lethal. This led to 18 filed cases of tumors and cancers among local residents of Ringwood. As early as 1980, the companys McCullom Lake factory located in McHenry County, Illinois, studies, paid for by Rohm and Haas, showed the groundwater never affected the towns well water. Monsanto Co. v. Rohm and Haas Co, list of companies based in the Philadelphia area Official website Rohm and Haas company history Rohm and Haas workers dead from brain cancer
22.
Trademark
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The trademark owner can be an individual, business organization, or any legal entity. A trademark may be located on a package, a label, for the sake of corporate identity, trademarks are often displayed on company buildings. A trademark identifies the owner of a particular product or service. The unauthorized usage of trademarks by producing and trading counterfeit consumer goods is known as brand piracy, the owner of a trademark may pursue legal action against trademark infringement. Most countries require formal registration of a trademark as a precondition for pursuing this type of action, the United States, Canada and other countries also recognize common law trademark rights, which means action can be taken to protect an unregistered trademark if it is in use. Still, common law trademarks offer the holder in general less legal protection than registered trademarks. A trademark may be designated by the symbols, ™ ℠ ® A trademark is typically a name, word, phrase, logo, symbol, design, image. There is also a range of non-conventional trademarks comprising marks which do not fall into these categories, such as those based on colour, smell. Trademarks which are considered offensive are often rejected according to a nations trademark law, the term trademark is also used informally to refer to any distinguishing attribute by which an individual is readily identified, such as the well-known characteristics of celebrities. When a trademark is used in relation to services rather than products, it may sometimes be called a service mark, in other words, trademarks serve to identify a particular business as the source of goods or services. The use of a trademark in this way is known as trademark use, certain exclusive rights attach to a registered mark. Different goods and services have been classified by the International Classification of Goods, in trademark treatises it is usually reported that blacksmiths who made swords in the Roman Empire are thought of as being the first users of trademarks. Other notable trademarks that have used for a long time include Löwenbräu. The first trademark legislation was passed by the Parliament of England under the reign of King Henry III in 1266, the first modern trademark laws emerged in the late 19th century. In France the first comprehensive system in the world was passed into law in 1857 with the Manufacture. In Britain, the Merchandise Marks Act 1862 made it an offense to imitate anothers trade mark with intent to defraud or to enable another to defraud. In 1875 the Trade Marks Registration Act was passed which allowed formal registration of marks at the UK Patent Office for the first time. Registration was considered to comprise prima facie evidence of ownership of a trade mark, in the United States, Congress first attempted to establish a federal trademark regime in 1870
23.
Polycarbonate
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Polycarbonates are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent and they are easily worked, molded, and thermoformed. Because of these properties, polycarbonates find many applications, Polycarbonates do not have a unique resin identification code and are identified as Other,7 on the RIC list. Products made from polycarbonate can contain the precursor monomer bisphenol A. Polycarbonates received their name because they are polymers containing carbonate groups, a balance of useful features, including temperature resistance, impact resistance and optical properties, positions polycarbonates between commodity plastics and engineering plastics. The main polycarbonate material is produced by the reaction of bisphenol A, the net reaction from the diphenoxide is, Na22CMe2 + COCl2 → 1/n n +2 NaCl In this way, approximately one billion kilograms of polycarbonate is produced annually. Many other diols have been tested in place of bisphenol A, e. g.1, the cyclohexane is used as a comonomer to suppress crystallisation tendency of the BPA-derived product. Tetrabromobisphenol A is used to enhance fire resistance, tetramethylcyclobutanediol has been developed as a replacement for BPA. Although it has high impact-resistance, it has low scratch-resistance, therefore, a hard coating is applied to polycarbonate eyewear lenses and polycarbonate exterior automotive components. The characteristics of polycarbonate compare to those of polymethyl methacrylate, but polycarbonate is stronger, Polycarbonate is highly transparent to visible light, with better light transmission than many kinds of glass. Polycarbonate has a transition temperature of about 147 °C, so it softens gradually above this point. Tools must be held at high temperatures, generally above 80 °C to make strain-free and stress-free products, low molecular mass grades are easier to mold than higher grades, but their strength is lower as a result. The toughest grades have the highest molecular mass, but are more difficult to process. Unlike most thermoplastics, polycarbonate can undergo plastic deformations without cracking or breaking. As a result, it can be processed and formed at room temperature using sheet metal techniques, even for sharp angle bends with a tight radius, heating may not be necessary. This makes it valuable in prototyping applications where transparent or electrically non-conductive parts are needed, pMMA/Acrylic, which is similar in appearance to polycarbonate, is brittle and cannot be bent at room temperature. Due to its chemical properties it is not conducive to laser-cutting, Injection molding into ready articles Polycarbonate may become brittle when exposed to ionizing radiation above 25 kGy. Polycarbonate is mainly used for applications that capitalize on its collective safety features. Being a good insulator and having heat-resistant and flame-retardant properties, it is used in various products associated with electrical
24.
Ultimate tensile strength
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In other words, tensile strength resists tension, whereas compressive strength resists compression. Ultimate tensile strength is measured by the stress that a material can withstand while being stretched or pulled before breaking. In the study of strength of materials, tensile strength, compressive strength, some materials break very sharply, without plastic deformation, in what is called a brittle failure. Others, which are more ductile, including most metals, experience some plastic deformation, the UTS is usually found by performing a tensile test and recording the engineering stress versus strain. The highest point of the curve is the UTS. It is a property, therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, Tensile strengths are rarely used in the design of ductile members, but they are important in brittle members. They are tabulated for common materials such as alloys, composite materials, ceramics, plastics, Tensile strength can be defined for liquids as well as solids under certain conditions. Tensile strength is defined as a stress, which is measured as force per unit area, for some non-homogeneous materials it can be reported just as a force or as a force per unit width. In the International System of Units, the unit is the pascal, or, equivalently to pascals, Many materials can display linear elastic behavior, defined by a linear stress–strain relationship, as shown in the left figure up to point 3. Beyond this elastic region, for materials, such as steel. A plastically deformed specimen does not completely return to its original size, for many applications, plastic deformation is unacceptable, and is used as the design limitation. The reversal point is the stress on the engineering stress–strain curve. The UTS is not used in the design of static members because design practices dictate the use of the yield stress. It is, however, used for quality control, because of the ease of testing and it is also used to roughly determine material types for unknown samples. The UTS is a common engineering parameter to design members made of material because such materials have no yield point. Typically, the testing involves taking a sample with a fixed cross-sectional area. When testing some metals, indentation hardness correlates linearly with tensile strength and this important relation permits economically important nondestructive testing of bulk metal deliveries with lightweight, even portable equipment, such as hand-held Rockwell hardness testers
25.
Flexural strength
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The flexural strength represents the highest stress experienced within the material at its moment of yield. It is measured in terms of stress, here given the symbol σ, when an object formed of a single material, like a wooden beam or a steel rod, is bent, it experiences a range of stresses across its depth. At the edge of the object on the inside of the bend the stress will be at its maximum compressive stress value, at the outside of the bend the stress will be at its maximum tensile value. These inner and outer edges of the beam or rod are known as the extreme fibers, most materials fail under tensile stress before they fail under compressive stress, so the maximum tensile stress value that can be sustained before the beam or rod fails is its flexural strength. The flexural strength would be the same as the tensile strength if the material were homogeneous, in fact, most materials have small or large defects in them which act to concentrate the stresses locally, effectively causing a localized weakness. When a material is bent only the extreme fibers are at the largest stress so, if those fibers are free from defects, therefore, it is common for flexural strengths to be higher than tensile strengths for the same material. Conversely, a material with defects only on its surfaces might have a higher tensile strength than flexural strength. If we dont take into account defects of any kind, it is clear that the material will fail under a force which is smaller than the corresponding tensile force. Both of these forces will induce the same failure stress, whose value depends on the strength of the material. The equation of these two stresses yields, σ =3 F L2 b d 2 Usually, L is much bigger than d, M. Hodgkinson, Mechanical Testing of Advanced Fibre Composites, Cambridge, Woodhead Publishing, Ltd. p. 132–133. Materials Science and Engineering, Hoken, John Wiley & Sons, ASTM C1161-02ce1, Standard Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature, ASTM International, West Conshohocken, PA
26.
Impact (mechanics)
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In mechanics, an impact is a high force or shock applied over a short time period when two or more bodies collide. Such a force or acceleration usually has an effect than a lower force applied over a proportionally longer period. The effect depends critically on the velocity of the bodies to one another. At normal speeds, during a perfectly inelastic collision, an object struck by a projectile will deform, however, these deformations and vibrations cannot occur instantaneously. A high-velocity collision does not provide sufficient time for these deformations and vibrations to occur, thus, the struck material behaves as if it were more brittle than it would otherwise be, and the majority of the applied force goes into fracturing the material. Or, another way to look at it is that actually are more brittle on short time scales than on long time scales. Impact resistance decreases with an increase in the modulus of elasticity, resilient materials will have better impact resistance. Different materials can behave in different ways in impact when compared with static loading conditions. Ductile materials like steel tend to become brittle at high loading rates. The way in which the energy is distributed through the section is also important in determining its response. Projectiles apply a Hertzian contact stress at the point of impact to a body, with compression stresses under the point. Since most materials are weaker in tension than compression, this is the zone where cracks tend to form, a nail is pounded with a series of impacts, each by a single hammer blow. These high velocity impacts overcome the friction between the nail and the substrate. A pile driver achieves the same end, although on a larger scale. An impact wrench is a designed to impart torque impacts to bolts to tighten or loosen them. At normal speeds, the applied to the bolt would be dispersed, via friction. However, at speeds, the forces act on the bolt to move it before they can be dispersed. In ballistics, bullets utilize impact forces to puncture surfaces that could otherwise resist substantial forces, a rubber sheet, for example, behaves more like glass at typical bullet speeds
27.
Acrylic acid
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Acrylic acid is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a group connected directly to a carboxylic acid terminus. This colorless liquid has a characteristic acrid or tart smell and it is miscible with water, alcohols, ethers, and chloroform. More than a million tons are produced annually, Acrylic acid is produced from propylene which is a byproduct of ethylene and gasoline production. CH2=CHCH3 + 3⁄2 O2 → CH2=CHCO2H + H2O Ethylene can be carboxylated to acrylic acid under supercritical carbon dioxide condition, because acrylic acid and its esters have long been valued commercially, many other methods have been developed but most have been abandoned for economic or environmental reasons. An early method was the hydrocarboxylation of acetylene, HCCH + CO + H2O → CH2=CHCO2H This method requires nickel carbonyl and it was once manufactured by the hydrolysis of acrylonitrile which is derived from propene by ammoxidation, but was abandoned because the method cogenerates ammonium derivatives. Other now abandoned precursors to acrylic acid include ethenone and ethylene cyanohydrin, dow Chemical Company and a partner, OPX Biotechnologies, are investigating using fermented sugar to produce 3-hydroxypropionic acid, an acrylic acid precursor. The goal is to reduce gas emissions. Acrylic acid undergoes the reactions of a carboxylic acid. When reacted with an alcohol, it forms the corresponding ester, the esters and salts of acrylic acid are collectively known as acrylates. The most common alkyl esters of acrylic acid are methyl, butyl, ethyl, as a substituent acrylic acid can be found as an acyl group or a carboxyalkyl group depending on the removal of the group from the molecule. More specifically these are, The acryloyl group, with the removal of the –OH from carbon-1, the 2-carboxyethenyl group, with the removal of a –H from carbon-3. This substituent group is found in chlorophyll, Acrylic acid is severely irritating and corrosive to the skin and the respiratory tract. Eye contact can result in severe and irreversible injury, low exposure will cause minimal or no health effects, while high exposure could result in pulmonary edema. Methacrylic acid Acryloyl chloride Acrylamide Acrylate polymer Sodium polyacrylate National Pollutant Inventory, Acrylic acid CDC - NIOSH Pocket Guide to Chemical Hazards - Acrylic acid
28.
Imperial Chemical Industries
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Imperial Chemical Industries was a British chemical company and was, for much of its history, the largest manufacturer in Britain. It was formed by the merger of leading British chemical companies in 1926 and its headquarters were at Millbank in London, and it was a constituent of the FT30 and later the FTSE100 Indexes. ICI made paints and speciality products, including ingredients, speciality polymers, electronic materials, fragrances. It was acquired by AkzoNobel in 2008, who immediately sold parts of ICI to Henkel, the company was founded in December 1926 from the merger of four companies, Brunner Mond, Nobel Explosives, the United Alkali Company, and British Dyestuffs Corporation. It established its office at Millbank in London in 1928. Competing with DuPont and IG Farben, the new company produced chemicals, explosives, fertilisers, insecticides, dyestuffs, non-ferrous metals, in its first year turnover was £27 million. In 1940, ICI started British Nylon Spinners as a joint venture with Courtaulds, ICI also owned the Sunbeam motorcycle business, which had come with Nobel Industries, and continued to build motorcycles until 1937. During the Second World War, ICI was involved with the United Kingdoms nuclear weapons programme codenamed Tube Alloys, in the 1940s and 50s, the company established its pharmaceutical business and developed a number of key products, including Paludrine, halothane, Inderal, tamoxifen, and PEEK. ICI formed ICI Pharmaceuticals in 1957, ICI developed a fabric in the 1950s known as Crimplene, a thick polyester yarn used to make a fabric of the same name. The resulting cloth is heavy and wrinkle-resistant, and retains its shape well, the California-based fashion designer Edith Flagg was the first to import this fabric from Britain to the USA. During the first two years, ICI gave Flagg a large advertising budget to popularise the fabric across America, in 1960, Paul Chambers became the first chairman appointed from outside the company. Chambers employed the consultancy firm McKinsey to help with reorganising the company and his eight-year tenure saw export sales double, but his reputation was severely damaged by a failed takeover bid for Courtaulds in 1961–62. In 1962, ICI developed the controversial herbicide, paraquat, ICI was confronted with the nationalisation of its operations in Burma on 1 August 1962 as a consequence of the military coup. In 1964, ICI acquired British Nylon Spinners, the company it had set up in 1940 with Courtaulds. ICI surrendered its 37.5 per cent holding in Courtaulds and paid Courtaulds £2 million a year for five years, in return, Courtaulds transferred to ICI their 50 per cent holding in BNS. BNS was absorbed into ICIs existing polyester operation, ICI Fibres, the acquisition included BNS production plants in Pontypool, Gloucester and Doncaster, together with research and development in Pontypool. Peter Allen was appointed chairman between 1968 and 1971 and he presided over the purchase of Viyella. Jack Callard was appointed chairman from 1971 to 1975 and he almost doubled company profits between 1972 and 1974, and made ICI Britains largest exporter
29.
Acrylate polymer
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Acrylate polymers belong to a group of polymers which could be referred to generally as plastics. They are noted for their transparency, resistance to breakage, and they are also commonly known as acrylics or polyacrylates. Acrylate polymer is used in cosmetics such as nail polish as an adhesive. Acrylate monomers used to form acrylate polymers are based on the structure of acrylic acid, which consists of a vinyl group, Acrylic elastomer has characteristics of heat and oil resistance. It is divided into old type and new type, Old types include ACM containing chlorine, other than the slightly better water resistance of ANM, there are no physical differences, even processability is poor for both types. Since prices are high, demand is not so high vis-à-vis the characteristics. On the other hand, the new type of acrylic rubber does not contain any chlorine despite its unclear chemical composition, processability has been improved, most of the tackiness to rolls, as well as staining problems related to mold have been solved. Major characteristics of acrylic rubber include heat resistance and oil resistance, since it does not have a double bond, acrylic rubber also boasts of good weatherability and ozone resistance. Its cold resistance is not that good, however, the saturation point is −15 ℃ for the old type and −28. −30 ℃ for the new type. In terms of vulcanization, the method for the old type is amine vulcanization. To minimize permanent deformation, the old type requires curing for 24 hours at a temperature of 150 ℃, on the other hand, for the new type, the press curing time and follow-up vulcanization time are significantly reduced by combining metal soap and sulfur. The rebound resilience and abrasion resistance of the new type are poor, the materials are used mainly for oil seals and packagings related to automobiles. PVAc copolymer emulsion adhesive of vinyl acetate and acrylic acid Polyacrylamide copolymer used as floculation agent in water treatment acrylates Acrylic Dishmaker
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Polyacrylonitrile
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Polyacrylonitrile, also known as Creslan 61, is a synthetic, semicrystalline organic polymer resin, with the linear formula n. Though it is thermoplastic, it does not melt under normal conditions and it melts above 300 °C if the heating rates are 50 degrees per minute or above. Almost all polyacrylonitrile resins are made from mixtures of monomers with acrylonitrile as the main component. It is a polymer used to produce large variety of products including ultra filtration membranes, hollow fibers for reverse osmosis, fibers for textiles. PAN fibers are the precursor of high-quality carbon fiber. It is a component repeat unit in several important copolymers, such as styrene-acrylonitrile and acrylonitrile butadiene styrene plastic, Polyacrylonitrile was synthesized for the first time in 1930 by Dr. Hans Fikentscher und Dr. Claus Heuck in the Ludwigshafen works of then IG Farben. It was not until 1931 when chemist Dr. Herbert Rein in charge of polymer chemistry at Bitterfeld plant of IG Farben obtained a sample of PAN while visiting the Ludwigshafen works. He did find pyridinium benzylchloride – an ionic liquid - would dissolve PAN, in 1942 Rein discovered an even better solvent for PAN dimethylformamide and developed a technical process to process PAN to fibres and films. However war-time decline of infrastructure impeded commencing production, the first large scale production of PAN then branded as „Orlon“ was assumed by Du Pont in 1946 based on a patent filed exactly seven days after a nearly identical German claim was filed. All commercial methods of production of PAN are based on free radical polymerization of Acrylonitrile, most of the cases, small amount of other vinyl comonomers are also used along with AN depending on the final application. Anionic polymerization also can be used for synthesizing PAN, for textile applications, molecular weight in the range of 40,000 to 70,000 is used. For producing carbon fiber higher molecular weight is desired and this data is demonstrated in the Indexes for Experimental Batches of PAN Precursor and Carbon Fibers Made from It table. Homopolymers of polyacrylonitrile have been used as fibers in hot gas filtration systems, outdoor awnings, sails for yachts, copolymers containing polyacrylonitrile are often used as fibers to make knitted clothing like socks and sweaters, as well as outdoor products like tents and similar items. If the label of a piece of clothing says acrylic, then it is out of some copolymer of polyacrylonitrile. It was made into spun fiber at DuPont in 1942 and marketed under the name of Orlon, Acrylonitrile is commonly employed as a comonomer with styrene, e. g. acrylonitrile, styrene and acrylate plastics. PAN absorbs many metal ions and aids the application of absorption materials, polymers containing amidoxime groups can be used for the treatment of metals because of the polymers’ complex-forming capabilities with metal ions. PAN has properties involving low density, thermal stability, high strength and these unique properties have made PAN an essential polymer in high tech. Its high tensile strength and tensile modulus are established by fiber sizing, coatings, production processes and its mechanical properties derived are important in composite structures for military and commercial aircraft
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Emulsion polymerization
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Emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomer, and surfactant. The most common type of polymerization is an oil-in-water emulsion. Water-soluble polymers, such as certain polyvinyl alcohols or hydroxyethyl celluloses, the name emulsion polymerization is a misnomer that arises from a historical misconception. Rather than occurring in emulsion droplets, polymerization takes place in the particles that form spontaneously in the first few minutes of the process. These latex particles are typically 100 nm in size, and are made of many individual polymer chains, the particles are stopped from coagulating with each other because each particle is surrounded by the surfactant, the charge on the surfactant repels other particles electrostatically. Emulsion polymerization is used to manufacture several commercially important polymers, many of these polymers are used as solid materials and must be isolated from the aqueous dispersion after polymerization. In other cases the dispersion itself is the end product, a dispersion resulting from emulsion polymerization is often called a latex or an emulsion. These emulsions find applications in adhesives, paints, paper coating and they are often preferred over solvent-based products in these applications due to the absence of VOCs in them. Advantages of emulsion polymerization include, High molecular weight polymers can be made at fast polymerization rates, by contrast, in bulk and solution free radical polymerization, there is a tradeoff between molecular weight and polymerization rate. The continuous water phase is an excellent conductor of heat, enabling fast polymerization rates without loss of temperature control, since polymer molecules are contained within the particles, the viscosity of the reaction medium remains close to that of water and is not dependent on molecular weight. The final product can be used as is and does not generally need to be altered or processed and this can result in significant chain transfer to polymer. Can not be used for condensation, ionic or Ziegler-Natta polymerization, the early history of emulsion polymerization is connected with the field of synthetic rubber. The idea of using an emulsified monomer in a suspension or emulsion was first conceived at Bayer, before World War I. The Bayer workers used naturally occurring polymers such as gelatin, egg albumin, by todays definition these were not true emulsion polymerizations, but suspension polymerizations. The first true emulsion polymerizations, which used a surface-active agent, after World War II, emulsion polymerization was extended to production of plastics. Manufacture of dispersions to be used in paints and other products sold as liquid dispersions commenced. Ever more sophisticated processes were devised to prepare products that replaced solvent-based materials, the first successful theory to explain the distinct features of emulsion polymerization was developed by Smith and Ewart, and Harkins in the 1940s, based on their studies of polystyrene. Smith and Ewart arbitrarily divided the mechanism of emulsion polymerization into three stages or intervals, subsequently it has been recognized that not all monomers or systems undergo these particular three intervals
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Living polymerization
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In polymer chemistry, living polymerization is a form of chain growth polymerization where the ability of a growing polymer chain to terminate has been removed. This can be accomplished in a variety of ways, chain termination and chain transfer reactions are absent and the rate of chain initiation is also much larger than the rate of chain propagation. The result is that the chains grow at a more constant rate than seen in traditional chain polymerization. Living polymerization is a method for synthesizing block copolymers since the polymer can be synthesized in stages. Additional advantages are predetermined molar mass and control over end-groups, Living polymerization is desirable because it offers precision and control in macromolecular synthesis. This is important since many of the properties of polymers result from their microstructure. While these polymerization reactions are similar, there is a distinct difference in the definitions of these two reactions. However, this distinction is still up for debate in the literature, after initial addition of monomer to the initiator system, the viscosity would increase, but eventually cease after depletion of monomer concentration. However, he found that addition of more monomer caused an increase in viscosity, indicating growth of the polymer chain and this was a major step in polymer chemistry, since control over when the polymer was quenched, or terminated, was generally not a controlled step. With this discovery, the list of potential applications expanded dramatically, today, living polymerizations are used widely in the development of various types of polymers or plastics. This is because chemists now have control of the chemical makeup of the polymer and, thus. This level of control rarely exists in non-living polymerization reactions, leaving this method as the synthetic route if attainable. The most common types of living polymerization reactions are anionic, cationic, free-radical, or ring-opening in nature, Fast Rate of Initiation Another key characteristic is that the rate of initiation must be much faster than the rate of chain propagation. This would allow all of the species to form before chain propagation begins so all of the chains grow at the same rate. Low Dispersity Dispersity or polydispersity index is an indication of the broadness in the distribution of polymer chains, Living polymers tend to have low Đ due to the absence of chain termination pathways as well as the rate of initiation being much faster than the rate of propagation. If chain termination are present then chains will die or become inactive at various times during the polymerization which leads to polymer chains with varying xn. As stated in the section, if the rate of propagation is much slower than the rate of initiation then all of the initiators will form the active species before the onset of propagation. When both of these characteristics are considered it becomes apparent that the concentration of active chains, that is those undergoing polymerization, predictable Molecular Weight Since termination and chain transfer are absent in living polymerization then each initiator that generates an active species will be responsible for one chain
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Petroleum
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Petroleum is a naturally occurring, yellow-to-black liquid found in geological formations beneath the Earths surface, which is commonly refined into various types of fuels. Components of petroleum are separated using a technique called fractional distillation and it consists of hydrocarbons of various molecular weights and other organic compounds. The name petroleum covers both naturally occurring unprocessed crude oil and petroleum products that are made up of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, usually zooplankton and algae, are buried underneath sedimentary rock, Petroleum has mostly been recovered by oil drilling. Drilling is carried out studies of structural geology, sedimentary basin analysis. Petroleum is used in manufacturing a variety of materials. Concern over the depletion of the earths finite reserves of oil, the burning of fossil fuels plays the major role in the current episode of global warming. The word petroleum comes from Greek, πέτρα for rocks and Greek, the term was found in 10th-century Old English sources. It was used in the treatise De Natura Fossilium, published in 1546 by the German mineralogist Georg Bauer, Petroleum, in one form or another, has been used since ancient times, and is now important across society, including in economy, politics and technology. Great quantities of it were found on the banks of the river Issus, ancient Persian tablets indicate the medicinal and lighting uses of petroleum in the upper levels of their society. By 347 AD, oil was produced from bamboo-drilled wells in China, early British explorers to Myanmar documented a flourishing oil extraction industry based in Yenangyaung that, in 1795, had hundreds of hand-dug wells under production. The mythological origins of the oil fields at Yenangyaung, and its hereditary monopoly control by 24 families, Pechelbronn is said to be the first European site where petroleum has been explored and used. The still active Erdpechquelle, a spring where petroleum appears mixed with water has been used since 1498, Oil sands have been mined since the 18th century. In Wietze in lower Saxony, natural asphalt/bitumen has been explored since the 18th century, both in Pechelbronn as in Wietze, the coal industry dominated the petroleum technologies. In 1848 Young set up a small business refining the crude oil, Young eventually succeeded, by distilling cannel coal at a low heat, in creating a fluid resembling petroleum, which when treated in the same way as the seep oil gave similar products. The production of oils and solid paraffin wax from coal formed the subject of his patent dated 17 October 1850. In 1850 Young & Meldrum and Edward William Binney entered into partnership under the title of E. W. Binney & Co. at Bathgate in West Lothian, the worlds first oil refinery was built in 1856 by Ignacy Łukasiewicz. The demand for petroleum as a fuel for lighting in North America, edwin Drakes 1859 well near Titusville, Pennsylvania, is popularly considered the first modern well
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Radical polymerization
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Free radical polymerization is a method of polymerization by which a polymer forms by the successive addition of free radical building blocks. Free radicals can be formed via a number of different mechanisms usually involving separate initiator molecules, following its generation, the initiating free radical adds monomer units, thereby growing the polymer chain. Free radical polymerization is a key route for obtaining a wide variety of different polymers. In 2001,40 billion of the 110 billion pounds of polymers produced in the United States were produced by radical polymerization. Free radical polymerization is a type of chain growth polymerization, along with anionic, cationic, initiation is the first step of the polymerization process. During initiation, a center is created from which a polymer chain is generated. Not all monomers are susceptible to all types of initiators, Radical initiation works best on the carbon-carbon double bond of vinyl monomers and the carbon-oxygen double bond in aldehydes and ketones. In the first step, one or two radicals are created from the initiating molecules, in the second step, radicals are transferred from the initiator molecules to the monomer units present. Several choices are available for these initiators, thermal decomposition, The initiator is heated until a bond is homolytically cleaved, producing two radicals. This method is used most often with organic peroxides or azo compounds, photolysis, Radiation cleaves a bond homolytically, producing two radicals. This method is used most often with metal iodides, metal alkyls, photoinitiation can also occur by bi-molecular H-abstraction when the radical is in its lowest triplet excited state. An acceptable photoinitiator system should fulfill the requirements, High absorptivity in the 300-400 nm range. Efficient generation of radicals capable of attacking the double bond of vinyl monomers. Adequate solubility in the binder system, should not impart yellowing or unpleasant odors to the cured material. The photoinitiator and any byproducts resulting from its use should be non-toxic, redox reactions, Reduction of hydrogen peroxide or an alkyl hydrogen peroxide by iron. Other reductants such as Cr2+, V2+, Ti3+, Co2+, persulfates, The dissociation of a persulfate in the aqueous phase. This method is useful in emulsion polymerizations in which the radical diffuses into a hydrophobic monomer-containing droplet, ionizing radiation, α-, β-, γ-, or x-rays cause ejection of an electron from the initiating species, followed by dissociation and electron capture to produce a radical. Electrochemical, Electrolysis of a solution containing both monomer and electrolyte, a monomer molecule will receive an electron at the cathode to become a radical anion, and a monomer molecule will give up an electron at the anode to form a radical cation
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. Bibcode:2014JMagR.242..233W. doi:10.1016/j.jmr.2014.02.005.