Morphology Development in Thermoplastic Vulcanizates (TPV)

摘要

The mechanisms of fragmentation and dispersion in molten polypropylene (PP) of several pre-crosslinked and plasticized ethylene-propylene-diene terpolymer (EPDM) networks were studied. The results highlight the importance of the gel fraction of the pre-crosslinked EPDMs on the quality of the dispersion of such networks. As a result, pre-crosslinked EPDM having a gel fraction below g_(EPDM)=0.7 can be finely and homogeneously fragmented and dispersed in presence of PP. Nevertheless, contrarily to some theoretical model expectations, a partial fragmentation of the chemical networks was always observed even at very high crosslink density (g_(EPDM)>0.7). It can be then admitted a collision-coalescence-separation type erosion mechanism of the EPDM domains. Finally, these results brought significant information on TPV morphology stabilization and their related mechanical properties.