Casein-formaldehyde polymer

In the crosslinking with formaldehyde of proteic macromolecules, such as casein, the polymer behaves at the same time as both substrate and amine reagent.Studies of the reaction between formaldehyde and ettllagen stress the importanee of aldehyde coneentration and pH value in the process. It is found that the number of methylene bridges formed for each collagen molecule (molecular weight about 10,(XK)) is nearly 15 the amino groups of lysine, hydroxylysine, and histidine present in the maeromol-ecule are suitable for the occurrence of the Mannich reaction. -" - ... 

Cellulose-based plastics, particularly cellulose nitrate and acetates, were the most commercially important semi-synthetics up to the 1940s and were used as the base for photographic film, textile fibres, moulded goods and in lacquers. Naturally occurring polymer cellulose in the form of cotton linters or wood pulp is chemically treated to increase its solubility. Cellulose has a high molecular weight of between 100000 and 500000 and an empirical formula C0H1OO5. Casein-formaldehyde is the only protein-based moulded plastic that achieved commercial success. It is based on cow s milk and is still produced in very small quantities for specialist items such as hand-coloured buttons. 

The first plastic was a mixture of cellulose nitrate and camphor invented in the 1860s by John Wesley Hyatt it was given the TM Celluloid. In 1899 Spit-teler developed a method of hardening casein with formaldehyde and thus founded the casein plastics industry, e.g., small items such as buttons. The earliest high-volume plastic, a condensation product of phenol and formaldehyde, was introduced by Leo Baekeland in 1907. Trademarked Bakelite, it was the first truly synthetic high polymer. Its chief use was as engineering material since its dark color limited its application to items in which color was not a factor. 

The first man-made polymer was nitrocellulose (NC). The main use of the NC resins was a replacement of the natural and expensive materials, viz., ivory, tortoise shell products, amber, ebony, onyx or alabaster. The use of cellulose acetate (CA) as a thermoplastic began in 1926. Cellulose ethers and esters became commercially available in 1927. Casein crosslinked by formaldehyde gave horn-like materials — Galalith has been used to manufacture shirt buttons, or as imitation of ivory and porcelain [Pontio, 1919]. 

Ammonia like urea, melamine, and casein reacts readily with formaldehyde to form polymer molecules. With aqueous reactants under controlled temperature conditions, hexamethylenetetramine of high purity is obtained. The process comprises mixing 30 per cent formaldehyde with 27 per cent ammonia, cooling the mixture, evaporating, centrifuging, drying, and milling. ... 

Let us mention, finally, that there is also a growing number of works di-reeled to the use of natural polymers. such as albumin, gelatin, or casein (104), For instance, albumin microspheres can be prepared by denaturalization (by heat treatment, or by formaldehyde addition) of natural albumin. In addition to being useful in the exploration, for diagnostic purposes, of the reticuloendothelial sys-... 

Features Formaldehyde-free highly reactive compat. with soy polymers, casein, latex, starch, gums, etc. replacement for melamine formaldehyde and urea formaldehyde... 

Uses Mfg. of phenolic and thermosetting resins, furan polymers, urea-formaldehyde resins wetting agent foundry sand binders corrosion-resist, resins intermediate for esterification and etherification paints solvent, plasticizer for phenolic resins solvent for dyes and resins nonreactive epoxy resin diluent vise, reducer, cure promoter, and carrier in amine-cured epoxy resins gel retarder in casein/protein glues polymer sealants/cements synthetic flavoring agent in foods and pharmaceuticals cosmetics ingred. in food-pkg. adhesives... 

The first semisynthetic polymer, celluloid, was prepared by Alexander Parkes in 1855. Adolph Spitteler and W. Kirsch prepared plastic from milk protein (casein) and formaldehyde in 1899. Buttons, handles, pens and piano keys were made from the new material and it was patented under the name Galalith (aka Erinoid in the United Kingdom). Fully synthetic Bakehte was fist formulated by Leo Hendrik Baekeland (1863-1944) in 1907, and the age of plastics began with the discovery and large-scale industrial production of vulcanized rubber (1910), PVC (1926), polystyrene (1931), synthetic robber (1931-1935), polyethylene (1933), nylon... 

The first macromolecular substances which fotmd technical interest were based on chemically modified natural materials, for example cellulose nitrate (Celluloid) or crosslinked casein (Galalith). Only with the onset of industrialisation in the nineteenth century did these renewable raw materials become the limiting factor for further growth, and chemists began developing artificial macromolecules based on fossil carbon sources like coal, oil, and gas. Polymers like condensation products from phenol and formaldehyde (Bakelite) started the plastics age in 1910 and polymers of styrene or vinyl chloride were used since about 1930 and until nowadays as important plastics. Presently, worldwide more than 260 million tons polymers per year are produced and used as plastics, films, fibres, and synthetic rubber. 

Prior to the 1930s all adhesives were based on natural products (eg, proteins such as animal blood, casein, soy protein). Use of adhesives from natural products steadily decreased thereafter with the development of synthetic polymers that had superior properties. Recently, renewed interest has been shown in using natural products to replace, entirely or in part, petroleum-based adhesive components with natural products, without sacrificing the performance levels achieved with modem petroleum-based adhesives. The purposes are often to reduce cost and dependence on petrochemicals, to reduce formaldehyde emissions, and improve selected properties (eg, biodegradability). 

While vulcanization of NR and GP was the first purposeful modification of natural polymers, the first man-made polymer was nitrocellulose, NC, discovered by Braconnot in 1833 (see Appendix I). Several commercial products followed, e.g., Collodion (lacquers based on alcohol-ether solution), Parkesine (the first thermoplastic material hot rolled and formable into variety of shapes), Ivorite (used as a substitute for ivory). Celluloid (camphor plasticized NC). Cellulose acetate, CA, was introduced in 1869 by Schutzenberger. Casein crosslinking by formaldehyde resulted in a 1885-patent hy Kritsche and Spitteler for what later became known as Galalith, a horn-like material quite successfully used even today as an imitation of ivory and porcelain [Seymour, 1982 1989]. 

Particleboards Wood particles, shives of flax flakes, saw dust, bagasse, hemp, kenaf, jute, cereal straw, coconut coir, corn and cotton stalks, rice husks, vetiver roots, and other fiber sources Urea, melamine, phenol formaldehyde resin, isocyanate, resorcinol, vinyl polyacetate resins and natural polymers, tannins, protein, casein, soybeans, modified starch, lignin activated by enzymatic system polylactic and polyhydroxyhutyric acid... 

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