CROSS-LINKING OF PVC AND NBR BLENDS

The purpose of our work is to control the interfacial bonds between PV C and NBR using the ammonium salts of triazine thiols and dithiodimorp holine (DTDM) and thereby reveal the relation between the interfacial bonds and the final mechanical properties of products. In the experime ntal work a two-stage process was used. At first, an NBR/PVC blend was mixed with a mono-tetra-n-butylammonium salt of triazine trithiol at a temperature of 100-degrees-C on a two-roll mill to give the branchin g structure of triazine thiols into PVC. In the second stage branched NBR/PVC reacted with DTDM to afford the branched PVC containing trithi omorphonyl groups. In the presence of ZnO at 160-degrees-C trithiomorp honyl groups react with NBR to form a crosslinking structure between N BR and PVC. The mechanical properties of cured NBR/PVC blends were mar kedly improved by the treatment process and after addition of tetramet hylthiuram monosulphide also. The mechanical properties were not impro ved by increasing the concentration of TT-TBA (tetrabutylammonium salt of 1,3,5-triazine-2,4,6-trithiol) over 4.2 phr.