Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane composite

Abstract

The thermal degradation behaviors of polycarbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy (E), in the case of isothermal degradation, was a quick increasing function of conversion (α) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.

Isothermal Decomposition Kinetic Analysis of Polymethylphenylsilsesquioxane/Epoxy Resin Systems

“…The curves of percent weight loss of EP and FREP systems versus time during thermal decomposition under isothermal conditions, produced by the analyses for various temperatures examined are presented in Figures 1-2. The maximum isothermal decomposition temperature was chosen so that the weight loss was less than 1% during the first minute because excessively fast and significant decomposition might occur during setting of the experimental temperature at the beginning of the experiments 15 . Thus, the thermal decomposition temperatures of 300, 310, 320 and 330 °C were chosen for EP and FREP systems.…”

Kinetics and Mechanism of Thermal Decomposition of Polyepoxyphenylsilsesquioxane/Epoxy Resin Systems from Isothermal Measurement

“…By plotting lnt against 1/T according to Equation 4, the activation energy can be calculated at any given a values from the slope of a regression straight line (23,24). decomposition rates emerges.…”