Mucilage is a thick, gluey substance produced by nearly all plants and some microorganisms. These microorganisms include protists; the direction of their movement is always opposite to that of the secretion of mucilage. It is an exopolysaccharide. Mucilage in plants plays a role in the storage of water and food, seed germination, thickening membranes. Cacti and flax seeds are rich sources of mucilage. Exopolysaccharides are the most stabilising factor for microaggregates and are distributed in soils. Therefore, exopolysaccharide-producing "soil algae" play a vital role in the ecology of the world's soils; the substance covers the outside of, for example, unicellular or filamentous green algae and cyanobacteria. Amongst the green algae the group Volvocales are known to produce exopolysaccharides at a certain point in their life cycle, it occurs in all plants, but in small amounts. It is associated with substances like tannins and alkaloids. Mucilage has a unique purpose in some carnivorous plants; the plant genera Drosera and others have leaves studded with mucilage-secreting glands, use a "flypaper trap" to capture insects.
Mucilage is edible. It is used in medicine. Traditionally, marshmallows were made from the extract of the mucilaginous root of the marshmallow plant as a cough medicine; the inner bark of the slippery elm, a North American tree species, has long been used as a demulcent and is still produced commercially for that purpose. Mucilage mixed with water has been used as a glue for bonding paper items such as labels, postage stamps, envelope flaps. Differing types and varying strengths of mucilage can be used for other adhesive applications, including gluing labels to metal cans, wood to china, leather to pasteboard. During the fermentation of nattō soybeans, extracellular enzymes produced by the bacterium Bacillus natto react with soybean sugars to produce mucilage; the amount and viscosity of the mucilage are important nattō characteristics, contributing to nattō's unique taste and smell. The mucilage of two kinds of insectivorous plants and butterwort, is used for the traditional production of a variant of the yoghurt-like Swedish dairy product called filmjölk.
The presence of mucilage in seeds affects important ecological processes in some plant species, such as tolerance of water stress, competition via allelopathy, or facilitation of germination through attachment to soil particles. Some authors have suggested a role of seed mucilage in protecting DNA material from irradiation damage; the amount of mucilage produced per seed has been shown to vary across the distribution range of a species, in relation with local environmental conditions of the populations. The following plants are known to contain far greater concentrations of mucilage than is found in most plants: Marine mucilage Mucilage McGraw-Hill Encyclopedia of Science and Technology, 5th edition. Mucilage Columbia Encyclopedia, Sixth Edition. Chisholm, Hugh, ed.. "Mucilage". Encyclopædia Britannica. 18. Cambridge University Press. P. 954
Urea-formaldehyde known as urea-methanal, so named for its common synthesis pathway and overall structure, is a non-transparent thermosetting resin or polymer. It is produced from formaldehyde; these resins are used in adhesives, particle board, medium-density fibreboard, molded objects. UF and related amino resins are a class of thermosetting resins of which urea-formaldehyde resins make up 80% produced globally. Examples of amino resins use include in automobile tires to improve the bonding of rubber to tire cord, in paper for improving tear strength, in molding electrical devices, jar caps, etc. Urea-formaldehyde resin's attributes include high tensile strength, flexural modulus, a high heat distortion temperature, low water absorption, mould shrinkage, high surface hardness, elongation at break, volume resistance, it has a refractive index of 1.55. The chemical structure of UF polymer consists of n repeat units. In contrast melamine-formaldehyde resins feature NCH2OCH2N repeat units. Depending on the polymerization conditions, some branching can occur.
Early stages in the reaction of formaldehyde and urea produce bisurea. 1 million metric tons of urea-formaldehyde are produced annually. Over 70% of this production is put into use by the forest products industry for bonding particleboard, medium density fiberboard, hardwood plywood, laminating adhesive. Urea-formaldehyde is pervasive. Examples include decorative laminates, paper, foundry sand molds, wrinkle resistant fabrics, cotton blends, corduroy, etc, it is used to glue wood together. Urea formaldehyde was used when producing electrical appliances casing. Foams have been used as artificial snow in movies. Urea formaldehyde is used in agriculture as a controlled release source of nitrogen fertilizer. Urea formaldehyde's rate of decomposition into CO2 and NH3 is determined by the action of microbes found in most soils; the activity of these microbes, therefore, the rate of nitrogen release, is temperature dependent. The optimum temperature for microbe activity is 70-90 °F. Urea-formaldehyde foam insulation dates to the 1930s and made a synthetic insulation with R-values near 5.0 per inch.
It is a foam, like shaving cream, injected or pumped into walls. It is made by using a pump set and hose with a mixing gun to mix the foaming agent and compressed air; the expanded foam is pumped into areas in need of insulation. It becomes firm within cures within a week. UFFI is found in homes built before the 1970s in basements, crawl spaces and unfinished attics. Visually it looks like oozing liquid, hardened. Over time, it tends to vary in shades of butterscotch but new UFFI is a light yellow color. Early forms of UFFI tended to shrink significantly. Modern UF insulation with updated catalysts and foaming technology have reduced shrinkage to minimal levels; the foam dries with a dull matte color with no shine. When cured, it has a dry and crumbly texture. Health effects occur when urea-formaldehyde based materials and products release formaldehyde into the air. There are no observable health effects from formaldehyde when air concentrations are below 1.0 ppm. The onset of respiratory irritation and other health effects, increased cancer risk begins when air concentrations exceed 3.0-5.0 ppm.
This triggers watery eyes, nose irritations and coughing, skin rash, severe allergic reactions, burning sensations in the eyes and throat and difficulty in breathing in some humans. Occupants of UFFI insulated homes with elevated formaldehyde levels experienced systemic symptoms such as headache, insomnia and loss of libido. Irritation of the mucous membranes was a common upper respiratory tract symptom related to formaldehyde exposure. However, when compared to control groups, the frequency of symptoms did not exceed the controls except when it came to wheezing, difficult breathing, a burning skin sensation. Controlled studies have suggested that tolerance to formaldehyde's odor and irritating effects can occur over a prolonged exposure, it was first synthesized in 1884 by Hölzer, working with Bernhard Tollens. In 1919, Hanns John of Prague, Czechoslovakia obtained the first patent for urea-formaldehyde resin. Urea-formaldehyde was object matter of judgment via the European Court of Justice of 5 February 1963, Case 26-62 Van Gend & Loos v Netherlands Inland Revenue Administration.
Phenol formaldehyde resin MDF-Safety aspects Urea formaldehyde History of urea-formaldehyde: Chapter 1 of: Carl Meyer, Urea-Formaldehyde Resins Urea-Formaldehyde Foam Insulation Indoor Air Quality: Formaldehyde Formaldehyde.... Its safe use in foundries
Cyanoacrylates are a family of strong fast-acting adhesives with industrial and household uses. They are various esters of cyanoacrylic acid; the acryl groups in the resin polymerises in the presence of water to form long, strong chains. They have some minor toxicity. Specific cyanoacrylates include methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, n-butyl cyanoacrylate, octyl cyanoacrylate and 2-octyl cyanoacrylate. Octyl cyanoacrylate was developed to address toxicity concerns and to reduce skin irritation and allergic response. Cyanoacrylate adhesives are sometimes known generically as power glues or superglues; the abbreviation "CA" is used for industrial grade cyanoacrylate. The original patent for cyanoacrylate was filed in 1942 by Goodrich Company as an outgrowth of a search for materials suitable for clear plastic gun sights for the war effort. In 1942, a team of scientists headed by Harry Coover Jr. stumbled upon a formulation that stuck to everything with which it came in contact. The team rejected the substance for the wartime application, but in 1951, while working as researchers for Eastman Kodak, Coover and a colleague, Fred Joyner, rediscovered cyanoacrylates.
The two realized the true commercial potential, a form of the adhesive was first sold in 1958 under the title "Eastman #910". During the 1960s, Eastman Kodak sold cyanoacrylate to Loctite, which in turn repackaged and distributed it under a different brand name "Loctite Quick Set 404". In 1971, Loctite developed its own manufacturing technology and introduced its own line of cyanoacrylate, called "Super Bonder". Loctite gained market share, by the late 1970s it was believed to have exceeded Eastman Kodak's share in the North American industrial cyanoacrylate market. National Starch and Chemical Company purchased Eastman Kodak’s cyanoacrylate business and combined it with several acquisitions made throughout the 1970s forming Permabond. Other manufacturers of cyanoacrylate include LePage, the Permabond Division of National Starch and Chemical, a subsidiary of Unilever. Together, Loctite and Permabond accounted for 75% of the industrial cyanoacrylate market; as of 2013 Permabond continued to manufacture the original 910 formula.
In its liquid form, cyanoacrylate consists of monomers of cyanoacrylate ester molecules. Methyl 2-cyanoacrylate has a molecular weight of 111.1 g/mol, a flashpoint of 79 °C, a density of 1.1 g/mL. Ethyl 2-cyanoacrylate has a molecular weight of 125 g/mol and a flashpoint of more than 75 °C. To facilitate easy handling, a cyanoacrylate adhesive is formulated with an ingredient such as fumed silica to make it more viscous or gel-like. More formulations are available with additives to increase shear strength, creating a more impact resistant bond; such additives may include rubber, as in Loctite's "Ultra Gel", or others. In general, the acryl groups undergo chain-growth polymerisation in the presence of water, forming long, strong chains, joining the bonded surfaces together; because the presence of moisture causes the glue to set, exposure to normal levels of humidity in the air causes a thin skin to start to form within seconds, which greatly slows the reaction. Cyanoacrylate adhesives have a short shelf life—about one year from manufacture if unopened, one month once opened.
The reaction with moisture can cause a container of glue, opened and resealed to become unusable more than if never opened. To minimise this reduction in shelf life, once opened, should be stored in an airtight container with a package of silica gel desiccant. Another technique is to insert a hypodermic needle into the opening of a tube. After using the glue, residual glue soon clogs the needle; the clog is removed by heating the needle before use. The polymerisation is temperature-dependent: storage below freezing point of water, 0 °C, stops the reaction, so keeping it in the freezer is effective. Cyanoacrylates are used as adhesives, they require some care and knowledge for effective use: they do not bond some materials. They have an exothermic reaction to natural fibres: cotton, leather, see reaction with cotton below. Cyanoacrylate glue has a low shearing strength, which has led to its use as a temporary adhesive in cases where the piece needs to be sheared off later. Common examples include mounting a workpiece to a sacrificial glue block on a lathe, tightening pins and bolts.
It is used in conjunction with another, but more resilient adhesive as a way of forming a joint, which holds the pieces in the appropriate configuration until the second adhesive has set. Cyanoacrylate-based glue has a weak bond with smooth surfaces and as such gives to friction. Cyanoacrylates are used to assemble prototype electronics, fl
Canada balsam called Canada turpentine or balsam of fir, is a turpentine made from the resin of the balsam fir tree of boreal North America. The resin, dissolved in essential oils, is a viscous, colourless or yellowish liquid that turns to a transparent yellowish mass when the essential oils have been allowed to evaporate. Canada balsam is amorphous. Since it does not crystallize with age, its optical properties do not deteriorate. However, it has poor solvent resistance. Due to its high optical quality and the similarity of its refractive index to that of crown glass and filtered Canada balsam was traditionally used in optics as an invisible-when-dry glue for glass, such as lens elements. Lenses glued with Canada balsam are called cemented lenses. Other optical elements can be cemented with Canada balsam, such as two prisms bonded to form a beam splitter. Balsam was phased out as an optical adhesive during World War II, in favour of polyester and urethane-based adhesives. In modern optical manufacturing, UV-cured epoxies are used to bond lens elements.
Canada balsam was commonly used for making permanent microscope slides. From about 1830 molten Canada balsam was used for microscope slides Canada balsam in solution was introduced in 1843, becoming popular in the 1850s. In biology, for example, it can be used to conserve microscopic samples by sandwiching the sample between a microscope slide and a glass coverslip, using Canada balsam to glue the arrangement together and enclose the sample to conserve it. Xylene balsam, Canada balsam dissolved in xylene, is used for preparing slide mounts; some workers prefer terpene resin for slide mounts, as it is both less acidic and cheaper than balsam. Synthetic resins have replaced organic balsams for such applications. Another important application of Canada balsam is in the construction of the Nicol prism. A Nicol prism consists of a calcite crystal cut into two halves. Canada balsam is placed between the two layers. Calcite is an anisotropic crystal and has different refractive indices for rays polarized along directions parallel and perpendicular to its optic axis.
These rays with differing refractive indices are known as the extraordinary rays. The refractive index for Canada balsam is in between the refractive index for the ordinary and extraordinary rays. Hence the ordinary ray will be internally reflected; the emergent ray will be linearly polarized, traditionally this has been one of the popular ways of producing polarized light. Some other uses include: in geology, it is used as a common thin section cement and glue and for refractive-index studies and tests, such as the Becke line test. Balm of Gilead, a healing compound made from the resinous gum of Commiphora gileadensis
Pelikan is a German manufacturer of fountain pens and other writing and art equipment. Credited with the invention of the differential-piston filling method, the original company was founded in Hanover in 1832 before it went bankrupt and restarted. Pelikan A. G. is now a Swiss incorporated subsidiary of Pelikan International. The notable history of Pelikan began with the model "100" and the modified 100N, which sparked the genesis of the company's distinctive styling. Pelikan is notable for its lack of innovation in pen manufacturing, preserving the innovative methods and styles of its founding company. Pelikan's newer lines of re-released pens have deviated little except to vary the sizes and coatings, it still manufactures many pens using cellulose acetate, instead of the more modern plastics used by most other major pen makers. Pelikan makes entry-level fountain pens and fountain pens for school pupils, for example "Pelikano" and "Future,"; the Griffix'Learn to Write' system was released in 2009 and starts at a wax crayon up to a fountain pen with right and left handed grip profiles.
Pelikan manufactures several grades of ink for use in fountain pens and dip pens. In 2009 Pelikan purchased its rival Herlitz. Current Pelikan product lines are: Discontinued products: Pelikanol — a white glue first made in 1904, similar in composition to today's glue sticks with a distinct marzipan scent. Pelikan Pelikan Online Shop Limited Edition History Pelikan Reference Pelikan History Most complete visual reference of Pelikan fountain pens Info for Pelikan fans and collectors HP sues Pelikan Pelikan's eraser collection A gallery of vintage advertisement
Gum arabic known as acacia gum, arabic gum, gum acacia, Senegal gum and Indian gum, by other names, is a natural gum consisting of the hardened sap of various species of the acacia tree. Gum arabic is collected from predominantly Acacia senegal and Vachellia seyal; the term "gum arabic" does not indicate a particular botanical source. In a few cases so‐called "gum arabic" may not have been collected from Acacia species, but may originate from Combretum, Albizia or some other genus; the gum is harvested commercially from wild trees in Sudan and throughout the Sahel, from Senegal to Somalia—though it is cultivated in Arabia and West Asia. Gum arabic is a complex mixture of glycoproteins and polysaccharides predominantly consisting of arabinose and galactose, it is soluble in water and used in the food industry as a stabilizer, with EU E number E414. Gum arabic is a key ingredient in traditional lithography and is used in printing, paint production, glue and various industrial applications, including viscosity control in inks and in textile industries, though less expensive materials compete with it for many of these roles.
While gum arabic is now produced throughout the African Sahel, it is still harvested and used in the Middle East. Gum arabic was defined by the 31st Codex Committee for Food Additives, held at The Hague from 19–23 March 1999, as the dried exudate from the trunks and branches of Acacia senegal or Vachellia seyal in the family Fabaceae. A 2017 safety re-evaluation by the Panel on Food Additives and Nutrient Sources of the European Food Safety Authority said that the term "gum arabic" does not indicate a particular botanical source. Gum arabic's mixture of polysaccharides and glycoproteins gives it the properties of a glue and binder, edible by humans. Other substances have replaced it where toxicity is not an issue, as the proportions of the various chemicals in gum arabic vary and make it unpredictable. Still, it remains an important ingredient in soft drink syrup and "hard" gummy candies such as gumdrops, M&M's chocolate candies. For artists, it is the traditional binder in watercolor paint, in photography for gum printing, it is used as a binder in pyrotechnic compositions.
Pharmaceutical drugs and cosmetics use the gum as a binder, emulsifying agent, a suspending or viscosity increasing agent. Wine makers have used gum arabic as a wine fining agent, it is an important ingredient in shoe polish, can be used in making homemade incense cones. It is used as a lickable adhesive, for example on postage stamps and cigarette papers. Lithographic printers employ it to keep the non-image areas of the plate receptive to water; this treatment helps to stop oxidation of aluminium printing plates in the interval between processing of the plate and its use on a printing press. Gum arabic is used in the food industry as a stabilizer and thickening agent in icing, soft candy, chewing gum and other confectionery and to bind the sweeteners and flavorings in soft drinks. A solution of sugar and gum arabic in water, gomme syrup, is sometimes used in cocktails to prevent the sugar from crystallizing and provide a smooth texture. Gum arabic is a soluble dietary fibre, a complex polysaccharide indigestible to both humans and animals.
It is considered safe for human consumption. There is indication of harmless flatulence in some people taking large doses of 30g or more per day, it is not degraded in the intestine, but fermented in the colon under the influence of microorganisms—it is a prebiotic. There is no scientific consensus about its caloric value; the US FDA set a value of 4 kcal/g for food labelling, but in Europe no value was assigned for soluble dietary fibre. A 1998 review concluded that "based on present scientific knowledge only an arbitrary value can be used for regulatory purposes". In 2008 the FDA sent a letter of no objection in response to an application to reduce the rated caloric value of gum arabic to 1.7 kcal/g. Gum arabic is used as a binder for watercolor painting because it dissolves in water. Pigment of any color is suspended within the acacia gum in varying amounts, resulting in watercolor paint. Water acts as a vehicle or a diluent to thin the watercolor paint and helps to transfer the paint to a surface such as paper.
When all moisture evaporates, the acacia gum does not bind the pigment to the paper surface, but is absorbed by deeper layers. If little water is used, after evaporation the acacia gum functions as a true binder in a paint film, increasing luminosity and helping prevent the colors from lightening. Gum arabic allows more subtle control over washes, because it facilitates the dispersion of the pigment particles. In addition, acacia gum slows evaporation of water, giving longer working time; the addition of a little gum arabic to watercolor pigment and water allows for easier lifting of pigment from paper and thus can be a useful tool when lifting out color when painting in watercolor. Gum arabic has a long history as additives to ceramic glazes, it acts as a binder, helping the glaze adhere to the clay before it is fired, thereby minimising damage by handling during the manufacture of the piece. As a secondary effect, it acts as a deflocculant, increasing the fluidity of the glaze mixture but making it more to sediment out into a hard cake if not used for a while.
The gum is made up into a solution in hot water (typica
A polyamide is a macromolecule with repeating units linked by amide bonds. Polyamides occur both and artificially. Examples of occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made through step-growth polymerization or solid-phase synthesis yielding materials such as nylons and sodium poly. Synthetic polyamides are used in textiles, automotive applications and sportswear due to their high durability and strength; the transportation manufacturing industry is the major consumer, accounting for 35% of polyamide consumption. Polymers of amino acids are known as proteins. According to the composition of their main chain, synthetic polyamides are classified as follows: All polyamides are made by the formation of an amide function to link two molecules of monomer together; the monomers can be amides themselves, α,ω-amino acids or a stoichiometric mixture of a diamine and a diacid. Both these kinds of precursors give a homopolymer. Polyamides are copolymerized, thus many mixtures of monomers are possible which can in turn lead to many copolymers.
Additionally many nylon polymers are miscible with one another allowing the creation of blends. Production of polymers requires the repeated joining of two groups to form an amide linkage. In this case this involves amide bonds, the two groups involved are an amine group, a terminal carbonyl component of a functional group; these react to produce a carbon-nitrogen bond. This process involves the elimination of other atoms part of the functional groups; the carbonyl-component may be part of either a carboxylic acid group or the more reactive acyl halide derivative. The amine group and the carboxylic acid group can be on the same monomer, or the polymer can be constituted of two different bifunctional monomers, one with two amine groups, the other with two carboxylic acid or acid chloride groups; the condensation reaction is used to synthetically produce nylon polymers in industry. Nylons must include a straight chain monomer; the amide link is produced from an amine group, a carboxylic acid group.
The hydroxyl from the carboxylic acid combines with a hydrogen from the amine, gives rise to water, the elimination byproduct, the namesake of the reaction. As an example of condensation reactions, consider that in living organisms, Amino acids are condensed with one another by an enzyme to form amide linkages; the resulting polyamides are known as polypeptides. In the diagram below, consider the amino-acids as single aliphatic monomers reacting with identical molecules to form a polyamide, focusing on the amine and acid groups. Ignore the substituent R groups – under the assumption the difference between the R groups are negligible: For aromatic polyamides or'aramids' e.g. Kevlar, the more reactive acyl chloride is used as a monomer; the polymerization reaction with the amine group eliminates hydrogen chloride. The acid chloride route can be used as a laboratory synthesis to avoid heating and obtain an instantaneous reaction; the aromatic moiety itself does not participate in elimination reaction, but it does increase the rigidity and strength of the resulting material which leads to Kevlar's renowned strength.
In the diagram below, Aramid is made from two different monomers which continuously alternate to form the polymer. Aramid is an aromatic polyamide: Polyamides can be synthesized from dinitriles using acid catalysis via an application of the Ritter reaction; this method is applicable for preparation of nylon 1,6 from adiponitrile and water. Additionally, polyamides can be synthesized from dinitriles using this method as well. Polyamide-imide Kohan, Melvin I.. Nylon Plastics Handbook. Hanser/Gardner Publications. ISBN 9781569901892