Radiation modification of starch-based plastic sheets

Transparent starch-based plastic sheets were prepared by irradiation of compression-molded starch-based mixture in physical gel state with electron beam (EB) at room temperature. The influence of radiation, plasticizers, water and poly vinyl alcohol (PVA) on the properties of the sheets was investigated. After irradiation, the ductility and tensile strength of the sheets was improved due to the chemical reactions, which was demonstrated by determination of gel fraction and DSC profiles, between starch macromolecules under the action of ionizing radiation. Glycerol, ethylene glycol (EG), poly ethylene glycol (PEG, 600, 1000) was selected as plasticizer to add into starch sheets. The results showed that glycerol was an excellent plasticizer of starch so that the ductility of starch sheets was improved obviously (elongation at break increased). The presence of water was necessary for the preparation of the sheets in this work. With the increasing of the content of starch in starch-based mixture, the tensile strength of the sheets decreased due to the decrease of the degree of the crosslinking of starch. Furthermore, PVA, a biodegradable and flexible-chain polymer, was incorporated into starch-based sheets, the properties of the sheets such as the flexibility (elongation at break) and wet strength was improved obviously. (C) 2003 Elsevier Science Ltd. All rights reserved.