INFLUENCE OF CHAIN MICROSTRUCTURE ON THERMODEGRADATIVE BEHAVIOR OF FURFURYL METHACRYLATE-N-VINYLPYRROLIDONE RANDOM COPOLYMERS BY THERMOGRAVIMETRY

The thermal behaviour of random copolymers of furfuryl methacrylate (F ) and N-vinyl-pyrrolidone (P) was studied by means of dynamic thermogr avimetric analysis (TGA) in the range 100-600 degrees C. The dynamic e xperiments show that these copolymers exhibit two degradation steps in the intervals 260-320 degrees C and 350-520 degrees C, respectively. The normalized weight loss in the low temperature interval increases a s the mole fraction of F in the copolymer m(F) increases, whereas an i nverted trend in the high temperature interval is observed. The appare nt activation energy Ea of the first degradation step for copolymers p repared with different composition, was obtained according to the trea tment suggested by Broido. A plot of the values of E(a) versus the F d iad molar fraction in the copolymer chains m(FF) gave a straight line that indicates that there is a direct relationship between the thermog ravimetric behaviour of these systems and their corresponding microstr ucture, that is, the distribution of comonomeric units along the copol ymers chains. The first decomposition step was also studied by isother mal TGA and a good linearity for the variation of the weight loss perc entage Delta W versus m(F) at least during the first 30 min of treatme nt was obtained. These results also indicate that from a kinetic point of view the isothermal degradation in these conditions follows a firs t order behaviour and the corresponding reaction rate constants increa se linearly with m(FF). (C) 1993 John Wiley and Sons, Inc.