THE INFLUENCE OF INTERFACIAL AGENTS ON THE IMPACT STRENGTH OF POLY(VINYL CHLORIDE) AND SOFT FILLER COMPOSITES

The impact strength of rigid poly(vinyl chloride) (PVC) filled with sc rap dust obtained from the buffing process in sports shoe sole manufac ture has been investigated. Dust from outsoles and midsoles which had been treated with silane and zirconate coupling agents were mixed into PVC at various levels of coupling agent addition. The effects of poly meric interfacial agents (compatibilisers) were studied for 15 differe nt agents by preparing them as masterbatches with the soft fillers, th en mixing them into the PVC at various levels of filler loading and co mpatibiliser level. The zirconate coupling agent performed better than the silanes. The improvement in impact strength however was not as hi gh as that achieved by using compatibilisers. Three good compatibilise rs were identified for midsole filled PVC and one for outsole filled P VC. The impact strength was dependent on the compatibiliser type and l evel, and on the filler type and loading. The good compatibilisers imp roved the dispersion level of the soft fillers in the PVC and gave hig h impact strength with no reduction in heat distortion temperature and only a slight drop in hardness. The tensile properties changed to giv e lower ultimate stress and higher elongation at break. The results sh ow that the addition of 2% of a good compatibiliser can double the Cha rpy notched impact strength of soft filled PVC, and give superior perf ormance at lower cost than a 5% loading of a commercial ABS impact mod ifier.