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International Union of Pure and Applied Chemistry
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The International Union of Pure and Applied Chemistry /ˈaɪjuːpæk/ or /ˈjuːpæk/ is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Council for Science, IUPAC is registered in Zürich, Switzerland, and the administrative office, known as the IUPAC Secretariat, is in Research Triangle Park, North Carolina, United States. This administrative office is headed by IUPACs executive director, currently Lynn Soby, IUPAC was established in 1919 as the successor of the International Congress of Applied Chemistry for the advancement of chemistry. Its members, the National Adhering Organizations, can be national chemistry societies, national academies of sciences, there are fifty-four National Adhering Organizations and three Associate National Adhering Organizations. IUPACs Inter-divisional Committee on Nomenclature and Symbols is the world authority in developing standards for the naming of the chemical elements. Since its creation, IUPAC has been run by different committees with different responsibilities. These committees run different projects which include standardizing nomenclature, finding ways to bring chemistry to the world, IUPAC is best known for its works standardizing nomenclature in chemistry and other fields of science, but IUPAC has publications in many fields including chemistry, biology and physics. IUPAC is also known for standardizing the atomic weights of the elements through one of its oldest standing committees, the need for an international standard for chemistry was first addressed in 1860 by a committee headed by German scientist Friedrich August Kekulé von Stradonitz. This committee was the first international conference to create an international naming system for organic compounds, the ideas that were formulated in that conference evolved into the official IUPAC nomenclature of organic chemistry. IUPAC stands as a legacy of this meeting, making it one of the most important historical international collaborations of chemistry societies, since this time, IUPAC has been the official organization held with the responsibility of updating and maintaining official organic nomenclature. IUPAC as such was established in 1919, one notable country excluded from this early IUPAC is Germany. Germanys exclusion was a result of prejudice towards Germans by the Allied powers after World War I, Germany was finally admitted into IUPAC during 1929. However, Nazi Germany was removed from IUPAC during World War II, during World War II, IUPAC was affiliated with the Allied powers, but had little involvement during the war effort itself. After the war, East and West Germany were eventually readmitted to IUPAC, since World War II, IUPAC has been focused on standardizing nomenclature and methods in science without interruption. In 2016, IUPAC denounced the use of chlorine as a chemical weapon, the letter stated, Our organizations deplore the use of chlorine in this manner. According to the CWC, the use, stockpiling, distribution, IUPAC is governed by several committees that all have different responsibilities. Each committee is made up of members of different National Adhering Organizations from different countries, the steering committee hierarchy for IUPAC is as follows, All committees have an allotted budget to which they must adhere. Any committee may start a project, if a projects spending becomes too much for a committee to continue funding, it must take the issue to the Project Committee
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Polymer
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A polymer is a large molecule, or macromolecule, composed of many repeated subunits. Because of their range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure, Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. The units composing polymers derive, actually or conceptually, from molecules of low molecular mass. The term was coined in 1833 by Jöns Jacob Berzelius, though with a distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, Polymers are studied in the fields of biophysics and macromolecular science, and polymer science. Polyisoprene of latex rubber is an example of a polymer. In biological contexts, essentially all biological macromolecules—i. e, proteins, nucleic acids, and polysaccharides—are purely polymeric, or are composed in large part of polymeric components—e. g. Isoprenylated/lipid-modified glycoproteins, where small molecules and oligosaccharide modifications occur on the polyamide backbone of the protein. The simplest theoretical models for polymers are ideal chains, Polymers are of two types, Natural polymeric materials such as shellac, amber, wool, silk and natural rubber have been used for centuries. A variety of natural polymers exist, such as cellulose. Most commonly, the continuously linked backbone of a used for the preparation of plastics consists mainly of carbon atoms. A simple example is polyethylene, whose repeating unit is based on ethylene monomer, however, other structures do exist, for example, elements such as silicon form familiar materials such as silicones, examples being Silly Putty and waterproof plumbing sealant. Oxygen is also present in polymer backbones, such as those of polyethylene glycol, polysaccharides. Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network, during the polymerization process, some chemical groups may be lost from each monomer. This is the case, for example, in the polymerization of PET polyester, the distinct piece of each monomer that is incorporated into the polymer is known as a repeat unit or monomer residue. Laboratory synthetic methods are divided into two categories, step-growth polymerization and chain-growth polymerization. However, some methods such as plasma polymerization do not fit neatly into either category
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Polycaprolactone
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Polycaprolactone is a biodegradable polyester with a low melting point of around 60 °C and a glass transition temperature of about −60 °C. The most common use of polycaprolactone is in the manufacture of speciality polyurethanes, polycaprolactones impart good water, oil, solvent and chlorine resistance to the polyurethane produced. This polymer is used as an additive for resins to improve their processing characteristics. Being compatible with a range of materials, PCL can be mixed with starch to lower its cost. Polycaprolactone is also used for splinting, modeling, and as a feedstock for prototyping systems such as Fused Filament Fabrication 3D Printers, PCL is prepared by ring opening polymerization of ε-caprolactone using a catalyst such as stannous octoate. Recently a wide range of catalysts for the ring opening polymerization of caprolactone have been reviewed, PCL is degraded by hydrolysis of its ester linkages in physiological conditions and has therefore received a great deal of attention for use as an implantable biomaterial. In particular it is interesting for the preparation of long term implantable devices. PCL has been approved by the Food and Drug Administration in specific applications used in the body as a drug delivery device, suture. It is being investigated as a scaffold for tissue repair via tissue engineering and it has been used as the hydrophobic block of amphiphilic synthetic block copolymers used to form the vesicle membrane of polymersomes. It is also used in housing applications, a variety of drugs have been encapsulated within PCL beads for controlled release and targeted drug delivery. The major impurities in the grade are toluene and tin. In dentistry, it is used as a component of night guards and it performs like gutta-percha, has similar handling properties, and for retreatment purposes may be softened with heat, or dissolved with solvents like chloroform. Similar to gutta-percha, there are master cones in all ISO sizes and accessory cones in different sizes, the major difference between the polycaprolactone-based root canal filling material and gutta-percha is that the PCL-based material is biodegradable but gutta-percha is not. There is lack of consensus in the dental community as to whether a biodegradable root canal filling material. PCL also has applications in the hobbyist market where it is known as InstaMorph, Polymorph, Shapelock, ReMoldables. It has physical properties of a tough, nylon-like plastic that softens to a putty-like consistency at only 60 °C. PCLs specific heat and conductivity are low enough that it is not hard to handle by hand at this temperature and this makes it ideal for small-scale modeling, part fabrication, repair of plastic objects, and rapid prototyping where heat resistance is not needed. Though softened PCL readily sticks to many other plastics when at higher temperature, if the surface is cooled, firmicutes and proteobacteria can degrade PCL
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Polymerization
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In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them, in chemical compounds, polymerization occurs via a variety of reaction mechanisms that vary in complexity due to functional groups present in reacting compounds and their inherent steric effects. Alkanes can also be polymerized, but only with the help of strong acids, further compounds either being referred to as oligomers in smaller molecules. Polymerization that is not sufficiently moderated and proceeds at a fast rate can be very hazardous and this phenomenon is known as hazardous polymerization and can cause fires and explosions. Step-growth polymers are defined as polymers formed by the reaction between functional groups of monomers, usually containing heteroatoms such as nitrogen or oxygen. Most step-growth polymers are classified as condensation polymers, but not all step-growth polymers release condensates, in this case. Step-growth polymers increase in weight at a very slow rate at lower conversions. To alleviate inconsistencies in these methods, adjusted definition for condensation and addition polymers have been developed. Chain-growth polymerization involves the linking together of molecules incorporating double or triple carbon-carbon bonds and these unsaturated monomers have extra internal bonds that are able to break and link up with other monomers to form a repeating chain, whose backbone typically contains only carbon atoms. Chain-growth polymerization is involved in the manufacture of such as polyethylene, polypropylene. A special case of chain-growth polymerization leads to living polymerization, in the radical polymerization of ethylene, its π bond is broken, and the two electrons rearrange to create a new propagating center like the one that attacked it. The form this propagating center takes depends on the type of addition mechanism. There are several mechanisms through which this can be initiated, the free radical mechanism is one of the first methods to be used. Free radicals are very reactive atoms or molecules that have unpaired electrons, taking the polymerization of ethylene as an example, the free radical mechanism can be divided into three stages, chain initiation, chain propagation, and chain termination. Free radical addition polymerization of ethylene must take place at temperatures and pressures. While most other free radical polymerizations do not require such extreme temperatures and pressures, one effect of this lack of control is a high degree of branching. Also, as termination occurs randomly, when two chains collide, it is impossible to control the length of individual chains, a newer method of polymerization similar to free radical, but allowing more control involves the Ziegler-Natta catalyst, especially with respect to polymer branching. Other forms of chain growth polymerization include cationic addition polymerization and anionic addition polymerization, cationic and anionic mechanisms are also more ideally suited for living polymerizations, although free radical living polymerizations have also been developed
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Polypropylene
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An addition polymer made from the monomer propylene, it is rugged and unusually resistant to many chemical solvents, bases and acids. Polypropylene has a relatively low energy surface that means that many common glues will not form adequate joints. Joining of polypropylene is often done using welding processes, in 2013, the global market for polypropylene was about 55 million tonnes. Polypropylene is the worlds second-most widely produced synthetic plastic, after polyethylene, Polypropylene is in many aspects similar to polyethylene, especially in solution behaviour and electrical properties. The additionally present methyl group improves mechanical properties and thermal resistance, the properties of polypropylene depend on the molecular weight and molecular weight distribution, crystallinity, type and proportion of comonomer and the isotacticity. In isotactic polypropylene, for example, the CH3 groups are oriented on one side of the carbon backbone and this creates a greater degree of crystallinity and results in a stiffer material that is more resistant to creep than both atactic polypropylene and polyethylene. The density of PP is between 0.895 and 0.92 g/cm³, therefore, PP is the commodity plastic with the lowest density. With lower density, moldings parts with lower weight and more parts of a mass of plastic can be produced. Unlike polyethylene, crystalline and amorphous regions differ only slightly in their density, however, the density of polyethylene can significantly change with fillers. The Youngs modulus of PP is between 1300 and 1800 N/mm², Polypropylene is normally tough and flexible, especially when copolymerized with ethylene. This allows polypropylene to be used as a plastic, competing with materials such as acrylonitrile butadiene styrene. Polypropylene has good resistance to fatigue, the melting point of polypropylene occurs at a range, so a melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Perfectly isotactic PP has a point of 171 °C. Commercial isotactic PP has a point that ranges from 160 to 166 °C, depending on atactic material. Syndiotactic PP with a crystallinity of 30% has a point of 130 °C. Below 0 °C, PP becomes brittle, the thermal expansion of polypropylene is very large, but somewhat less than that of polyethylene. Polypropylene is at room temperature resistant to fats and almost all organic solvents, non-oxidizing acids and bases can be stored in containers made of PP. At elevated temperature, PP can be dissolved in nonpolarity solvents such as xylene, due to the tertiary carbon atom PP is chemically less resistant than PE
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Resin identification code
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It was developed originally by the Society of the Plastics Industry in 1988, but has been administered by ASTM International since 2008. The Society of the Plastics Industry introduced the Resin Identification Code system in 1988 as a number of communities were implementing recycling programs. Plastics must be recycled separately, with materials, in order to preserve the material’s value. In its original form, the used as part of the RIC consisted of arrows that cycle clockwise to form a triangle that encloses a number. When a number is omitted, the arrows arranged in a form the universal Recycling Symbol. In 2008, ASTM International took over the administration of the RIC system, in 2013 this standard was revised to change the graphic marking symbol of the RIC from the chasing arrows of the Recycling Symbol to a solid triangle instead. Since its introduction, many have used the RIC as a signifier of recyclability, when many plastics recycling programs were first being implemented in communities across the United States, only plastics with RIC Codes 1 and 2 were accepted to be recycled. The list of acceptable plastic items has grown since then, and in some areas municipal recycling programs can collect and successfully recycle most plastic products regardless of their RIC Code. This has led some communities to instruct residents to refer to the form of packaging when determining what to include in a recycling bin. Modifications to the RIC are currently being discussed and developed by ASTMs D20.95 subcommittee on recycled plastics. In the U. S. the Sustainable Packaging Coalition has also created a How2Recycle label in an effort to replace the RIC with that more closely with how the public currently uses the RIC. Rather than indicating what type of plastic resin a product is made out of, the How2Recycle labels also encourage consumers to check with local facilities to see what plastics each municipal recycling facility can accept. Your Recycling Quandaries Information from Co-op America about what happens when plastic is recycled. Resin Codes from the American Chemistry Council
