Thermal stability, swelling behaviour and dielectric properties of NBR/PVC-PVAc blends

Blends of butadiene-acrylonitrile-rubber (NBR) and vinyl chloride/vinyl ace tate copolymer (PVC/PVAc) were prepared in various ratios. The viscosity me asurements and scanning electron microscopy revealed that NBR and PVC/PVAc copolymers are compatible in all ratios. Comparative studies of the curing characteristics of such blends as well as physico-mechanical properties, sw elling behaviour and dielectric measurements of their vulcanizates were inv estigated. The test cure system ethylene thiourea/sulphur (ETU/S) and the c onventional cure system cyclohexyl benzothiazole sulphenamide/tetramethylth iuram disulphide/sulphur (CBS/TMTD/S), both produce crosslinking effects wh ich are comparable to each other; particularly with respect to physico-mech anical properties of the blend vulcanizates and their degree of swelling in motor oil. Also, the dielectric measurements taken for the(.) blend vulcan izates containing various white fillers indicate a substantial decrease in the dielectric constant (epsilon') and the dielectric loss (epsilon ").