Aging behavior and thermal degradation of fluoroelastomer reactive blends with poly-phenol hydroxy EPDM

In this paper, the aging behavior of the reactive blends of fluoroelastomer (FPM) with poly-phenol hydroxy ethylene propylene diene monomer rubber (PHEPDM) in hot air was firstly investigated. The aging mechanism was analyzed by the swelling experiment, attenuated total-reflectance Fourier-transform infrared (FTIR-ATR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that the aging process increased the crosslinking density and the content of double bond. The O/F or O/C ratios increased and then decreased during aging because of the oxidation reaction of molecular chain and the surface migration of fluoro group. Secondly, thermogravimetric analysis (TGA) was used to study the thermal degradation behavior of the reactive blends. The apparent degradation activation energy (E) of FPM/PHEPDM reactive blends was calculated by the Kissinger and Coats-Redfern methods, respectively. The results showed that the FPM/PHEPDM reactive blends had higher thermal degradation temperature but lower E than FPM. Both the thermal degradation process of FPM/PHEPDM reactive blends and FPM were determined by nucleation and growth mechanism (Ann). The general mechanism function was [In(1 alpha)](1/m). The optimum value of m was between 1/3 and 1/2 for FPM/PHEPDM reactive blends, but 1/2 for FPM. From the results above, it was deduced that the special structure of PHEPDM made itself surrounded by fluoroelastomer and protected from hot-air aging and thermal degradation. (C) 2008 Elsevier Ltd. All rights reserved.