| Co-Investigator(Kenkyū-buntansha) |
SHIMAMOTO Shu Daicel Chemical Industries, Ltd., Central Laboratory, Research Scientist, 研究本部総合研究所, 研究員
YOSHIOKA Mariko Kyoto Univ., Faculty of Agr., Assist.Professor, 農学部, 助手 (30220594)
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| Research Abstract |
It has been found very recently by C.M.Buchanan and his coworkers that cellulose acetates with the degree of substitution up 2.5 are degradable in the environment and that the rate of biodegradation is influenced by its degree of substitution. Additionally, the biodegradation of cellulose acetates was conclusively established with a naturally devised mixed microbial culture derived from an activated sludge and ^<14>C labeled cellulose esters.
These observations have strengthened the idea that biodegradable plastics can be introduced from cellulose acetates. What is needed now is enrichment of thermoplastic properties of the cellulose acetates, since, without proper and reasonable plasticization, cellulose acerate cannot be used as plastics.
Blends of cellulose esters and aliphatic polyesters have been prepared during these several years by western investigators using melt compounding. Compatibility of the cellulose esters and the polyesters is the main subject to be investigated, but the
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object of this studies is to realize practical and biodegradable plastics from the cellulose esters. Under these background, we have been also trying to develop biodegradable plastics from cellulose esters and ethers by using a reactive processing procedure. This procedure includes oligoesterification of cellulose derivatives or likes with some hydroxyl groups remained. This causes a grafting, that is, an internal plasticization. It was found that the bleeding-out of the homo-oligomer, which is acting as external plasticizer, can be depressed, when the amounts of grafting become larger. Dicarboxylic acid anhydrides and monoepoxides or glycerine, epsilon-caprolactum and monoepoxides are successfully reacted in the presence of cellulose acetates at a relatively high temperature under certain torque by which all the compounds are melted, resulting in biodegradable plastics. In this concern, a new technique could be developed, by which grafted oligomers chemically bonded to CA can be separated from homo-oligomers quantitatively and completely. In its extension, methodology and conditions are pursued to improve the amounts of grafting. Less
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