THERMAL-BEHAVIOR OF CELLULOSIC GRAFT-COPOLYMERS .1. COTTON GRAFTED WITH VINYL-ACETATE AND METHYL ACRYLATE

The thermal degradation of samples of cotton, cotton oxidized by ceric ion, cotton grafted with vinyl acetate and methyl acrylate having different percent grafting yield, poly(vinyl acetate), and poly(methyl acrylate) has been investigated using the techniques of thermogravimetric analysis (TGA) and differential thermal analysis (DTA) in nitrogen. The kinetic parameters E, n, and A have been obtained following several methods of thermogravimetric analyses. The ceric ion redox system shows little effect upon thermic properties of cotton cellulose. Graft copolymerization of vinyl acetate makes cotton thermally less stable, while, in the case of methyl acrylate grafted cotton samples having 33, 83, and 174% grafting yield, the initial decomposition starts at lower temperatures; but decomposition beyond 360°C takes place at higher temperatures than those for ungrafted cotton, and in the case of the sample with 430% grafting yield the thermal stability is higher than that of original cotton. The thermal stability of cotton grafted with methyl acrylate is higher than that of cotton grafted with vinyl acetate. The degradation of cellulose and cellulose graft copolymers is complex as is shown by DTA thermograms and kinetic parameters. Copyright © 1990 John Wiley & Sons, Inc.