|
In this study, a new analytical method based on the parallel
competed concept wwas employed to describe the thermal
degradation behavior ofpolymers, and verified by various
techniques such as TGA/FTIR, Pyrolysis/GC/MS,TG/MS and residual
analysis etc. The method were applied to predict the degradation
of poly(methyl methacrylate) (PMMA) and epoxy system, both
blended propyl ester phosphazene (FR), and epoxy cured with
phenyl phosphorodiamidate,respectively. The result showed
that the thermal degradation mechanism of pure PMMA wasdominated
by zero and first-order reaction. For PMMA blended with FR, the
thermal degradation mechanism was dominated by first and second
order reactiondue to the formation of anhydride from the ester
group of PMMA and release ofmethanol. In addition the major
thermal degradation temperature of blends wasgreater than pure
PMMA. It was found from the study of epoxy system (EP) that
the thermal degradation of EP was accelerated and the residual
char yield at high temperature was obviously increased by
blending with FR. And the difference of degradation products
between pure epoxy and its blends were found to be acetone and
isopropyl phenol. In addition the thermal degradation
mechanismof pure EP was dominated by first-order reaction. For
EP blended with FR, thethermal degradation mechanism was
dominated second-order reaction. The major thermal
degradation temperature and residual char yield of
epoxycontaining phosphorus in main chain (reacted type) was
greater than EP blendedwith FR. However, less acetone was found
in the degraded products of reacted type epoxy. In addition the
thermal degradation mechanism of reacted type epoxywas
alwaysdominated by second-order reaction. And the thermal
activation energy spectra of reacted type was similar to that of
pure epoxy.
|