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Thermoplastic starch revisited. Structure/property relationship for “dialed‐in” biodegradability
Author(s) -
Zdrahala Richard J.
Publication year - 1997
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19971230112
Subject(s) - starch , thermoplastic , vinyl alcohol , materials science , plasticizer , chemical engineering , potato starch , biodegradation , amylose , polymer , composite material , polymer chemistry , crystallinity , amylopectin , polymer science , organic chemistry , chemistry , engineering
Starch, totally biodegradable polysaccharide biosynthesized by numerous plants, is one of the most abundant renewable resources known to man. Composed mostly from linear amylose and highly branched amylopectin, the starch, in its granular form, is a crystalline material. When mixed with limited amount of water and subjected to heat and shear, starch undergoes spontaneous destructurization. Homogeneous melt, possessing thermoplastic character is formed, called thermoplastic starch. It absorbs between 5 and 30 % of water at relative humidity range 0 to 90 %. Water is principal plasticizer of this material changing its original stiffness from glass‐like to natural gumlike substance. This plasticization is accompanied by significant dimensional changes. Many polymers, both hydrophilic and hydrophobic, were blended with starch to modify its moisture sensitivity. To illustrate influence of admixed polymers on its moisture sensitivity and its effect on properties and biodegradability, poly(vinyl alcohol), poly(ethylene‐co‐vinyl alcohol) and poly(ethylene‐co‐methacrylic acid) were added to potato starch. This paper discusses results and observed trends.