EFFECT OF HEAT AGING ON THE PROPERTIES OF A NYLON-6,6 POLY(PHENYLENE OXIDE) BLEND

Accelerated aging of an initial formulation of a nylon 6,6/poly(phenyleneoxide) (PA/PPO) blend resulted in a signifiant loss in impact strength after a relatively short aging period. Fourier transform infrared (FTIR) spectroscopy showed considerable surface oxidation air-aged samples. Scanning electron micrographs (SEM) of fracture surfaces showed evidence of embrittlement (glassy skin formation). This brittle skin apparently influenced crack propagation throughout the entire cross section of the test specimens. It was determined by nuclear magnetic resonance (NMR) analysis that the PPO phase of the blend contained a poly(styrene-butadiene) copolymer, probably added as an impact modifier. The susceptibility of the polybutadiene to oxidation, especially at elevated temperature, is believed to have caused the oxidation and surface embrittlement.