Casein plastics

Casein plastics are today produced by the dry process . Although a wet process was used originally in Great Britain it has been obsolete for over 50 years and need not be discussed here. 

Table 30.2 Some physical properties o casein plastics...

Both acids and alkalis will adversely affect the material. Strong alkalis and acids will cause decomposition. The water absorption is high and consequently casein is easily stained. As a corollary to this it may be dyed without difficulty. Acidic and basic water-soluble dyes are normally used. Typical properties of casein plastics are given in Table 30.2. 

The use of casein plastics was severely curtailed with the development of synthetic polymers, particularly after the Second World War. In addition stricter regulations concerning health and safety at work will have caused attention to be drawn to the formolising process. In the experience of the author the environment surrounding the formolising baths is most unpleasant and this will have accelerated the demise of the casein manufacturing industry. 

In the past casein plastics were widely used for decorative applications where a pleasant appearance was of value. The button industry was by far the largest user with further use for buckles, slides, hair pins, knitting pins, pens and pencils. 

COLLINS, j. H., Casein Plastics, Plastics Institute Monograph No. C5, 2nd Edn, London (1952)... 

Chemical nature Isolation of casein from milk Production of casein plastics Properties of casein Applications Miscellaneous Protein Plastics Derivatives of Natural Rubber Gutta Percha and Related Materials Shellac... 

Quantities of casein plastics were cut from rod stock into button blanks, and finished by drilling (to form holes for the thread) and by polishing. For a time the plastic knitting needle (for home knitting) was another important use for the materials, but such needles were broken easily and were unsuitable for delicate work. 

However, although the casein plastics extended the range of colours and effects available from the contemporary materials they were not distinctive enough to survive in competition with plastics based on oil, and have no commercial significance today. 

Ultraviolet light. Some shells - for example, mother-of-pearl -fluoresce a chalky-white under UV light. In conch cameos the white area has a stronger fluorescence than the pink, and in helmet cameos the brown or orange layer can be inert. With the exception of casein, plastics are inert. 

Munro PA, Southward CR, and Elston PD. The effect of casein manufacturing variables on the properties of rennet casein plastics. NZ J. Dairy Sci. Technol. 1980 115 177-190. 

The classification of polymers previously described has been used in this book for the discussion of pyrolysis results. An important class of polymers that is not discussed here is that of chemically modified natural polymers (or semisynthetic polymers). Examples of such polymers are the modified celluloses (carboxymethyl cellulose, ethyl cellulose, etc ), modified starches, casein plastics (Galalith), etc. These types of compounds were discussed in the book on pyrolysis of natural organic polymers [2]. 

Use Imparting heat resistance and pearlescence to polystyrene and casein plastics. 

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. 

Some physical properties of casein plastics are given in Table 4. 

Alcohol resins, polyvinyl Alkyd resins Allyl resins Butadiene copolymers, containing less than 50 percent butadione Carbohydrate plastics Casein plastics Cellulose nitrate resins Cellulose propionate (plastics) Coal tar resins Condensation plastics Coumarone-iodene resins Cresol resins Cresol-furfural resins Dicyandiamine resins Diisocyanate resins Elastomers, nonvulcanizable (plastics)... 

In nature the enzymes are able to convert cheap feedstocks such as sugars and amino acids into a large variety of functional and structural polymers with very high complexity. For many years, biopolymers such as starch, dextrose, cellulose, shellac, casein plastics, and proteins were used as polymers from renewable resources to formulate adhesives [9]. The life sciences effort is promoting the development of new processes based upon biotechnological routes to carbo-... 

German chemists Krische and Spitteler make formaldehyde-casein plastic... 

Uses Imparts heat resistance and pearlescence to polystyrene and casein plastics Lead phosphite dibasic CAS 1344-40-7... 

PEG-10 stearate Sodium laureth sulfate Sodium lauryl sulfate pearlescent, bubble baths PEG-3 distearate pearlescent, casein plastics Lead phosphate, dibasic pearlescent, cellulosics Bismuth subsalicylate pearlescent, cosmetics Bismuth oxychloride Cetearyl octanoate Cl 77163 Dioctyl dimer dilinoleate Glyceryl isostearate... 

J. H. Collins, Casein, Plastics and Allied Materials, Plastics Inst., London, 1952. 

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