THE EFFECT OF ADDITION OF BISMALEIMIDE AND MALEATED PP WAX ON THE CRYSTALLIZATION AND MECHANICAL-PROPERTIES OF PP NR BLENDS/

Blends of polypropylene and natural rubber SMR-CV with coupling agent (80:20 blends of PP/SMR-CV) were compounded in a twin-screw extruder. The coupling agents used were m-phenylenebismaleimide (HVA-2) and Epol ene wax (E-43). For both types of coupling agent, the tensile strength and the viscosity of the blends showed an increase, while the Rockwel l hardness showed a decrease with increasing coupling agent added. In comparison to Epolene E-43, the blends with HVA-2 showed a greater vis cosity increment and the extrudates exhibited higher die-swell values. The notched Izod impact-strength (at room and subambient temperatures ) of the blends with HVA-2 was also noted to be higher, in comparison, than blends with E-43. In this system, 0.2% addition of coupling agen t to the blends was optimal in obtaining the most desirable balance of properties. Investigation of crystallisation behaviour of PP in PP/SM R-CV blends was carried out using differential scanning calorimetry (D SC). The effect of the coupling agents on nucleation and growth rate ( of crystallisation), crystallite size distribution and crystallinity w as determined from exothermic crystallisation peaks of the blends, and the results obtained were correlated with the tensile properties.