Temperature dependence of the degree of compatibility in SBR–NBR blends by ultrasonic attenuation measurements: influence of unsaturated polyester additive

The dependence of ultrasonic attenuation coefficient on temperature is measured for styrene–butadiene rubber (SBR), acrylonitrile–butadiene rubber (NBR) and their blends (SBR/NBR=25/75, 50/50, 75/25 by wt) in the temperature range from 240 to 342 K at ultrasonic frequency of 5 MHz. The obtained ultrasonic relaxation peaks due to glass–rubber transition were used to investigate the degree of compatibility (DC) in the blends as well as its variation with temperature. The addition of 10 phr of unsaturated polyester resin (based on p-carbethoxy phthalanilic acid and maleic anhydride with ethylene glycol) to the blend showed improvement of DC in certain temperature ranges and deterioration of DC in other temperature ranges.