Radiation crosslinking of poly(vinyl chloride)/epoxidized natural rubber blend: effect of lead stabilization of the poly(vinyl chloride) phase

The irradiation crosslinking of 50/50 poly(vinyl chloride)/epoxidized natur al rubber blend was investigated in the presence of 1-5 parts per hundred r esin (phr) tribasic lead sulfate (TBLS) with blends prepared at various mix ing temperatures. The blends were irradiated using a 3.0 MeV electron accel erator at 0, 100 and 200 kGy irradiation doses. Changes in tensile strength , elongation at break and stress-strain curves of the blends with the incre ase TBLS content and blending temperatures were observed before and after i rradiation. The results on the tensile properties revealed the inhibition o f the irradiation-induced crosslinking by the TBLS although it stabilizes t he blend against thermal and irradiation-induced degradation. The Fourier t ransform infrared spectroscopy studies further confirmed these observations . Control on the thermal degradation of the blend during blending found to be crucial in achieving maximum enhancement in blend properties upon irradi ation. Evidence from dynamic mechanical analysis was also used to support t his contention. Addition of 2phr TBLS and blending at 150 degreesC found to be adequate in order to achieve the best enhancement in blend properties t hrough irradiation-induced crosslinking. (C) 2001 Society of Chemical Indus try.