Although numerous developments have been reported on how starch can be used to make plastics, these have failed to achieve large-scale market reality, largely because better and lower cost plastics can be made from other raw materials, particularly petroleum. Decreasing availability and increasing prices of conventional raw materials, coupled with a greater demand for plastics, are forcing industry to consider starch in plastics, especially those that are biodegradable and flame-resistant. By 1980 the rigid urethane foam market could use 100 million pounds annually of starch-derived products, such as sorbitol, methyl glucoside, and glycol glycosides. Currently, only 1 to 2 million pounds of sorbitol enter this market. In the next few years, major growth is predicted for disposable packaging, food trays, plates, and eating utensils. Many of these articles could be made with starch as a filler to improve the rate of biodegradation upon disposal. Plastic films serve certain agricultural applications, but their failure to deteriorate causes problems. The largest application is for mulching where films are needed to provide weed control, conserve moisture and nutrients, and warm the soil for early crop production. The technology is available for incorporating starch materials in polyurethanes, in films, as filler for a great variety of resins, and for improving flame resistance of plastics.
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