EFFECT OF COMPATIBILIZATION ON THE PROPERTIES OF POLYAMIDE-66 POLYPROPYLENE (75 25 WT/WT) BLENDS/

Blends consisting of a polyamide 66 (PA) matrix (75 wt%) and a dispers ed isotactic polypropylene (PP) phase were prepared by extrusion with anhydride-grafted isotactic polypropylene compatibilizers, one of high anhydride content (HAC, 2.7 wt% grafted maleic anhydride) and one of low anhydride content (LAC, 0.2 wt% grafted anhydride). HAC and LAC ha d similar effects on PP domain size and tensile properties at equal lo adings, unlike the anhydride concentration dependency that had been re ported for high PP content blends. As compatibilizer loading increased from 0 wt% to 7.5 wt%, a skin/core injection-moulded morphology gradi ent diminished, PP domain size decreased to less than 1 mu m, tensile strain increased and microscale deformation of the PP phase progressed from debonding to particle drawing and debonding to fibril fracture. The PP phase deformation mode depends on the interfacial strength as c ompared to the PP domain strength. HAC and LAC are postulated to behav e similarly because of sufficient reactivity with PA and similar surfa ce coverage by HAC-g-PA and LAC-g-PA. Interfacial strength is postulat ed to increase with decreasing particle size because of increasing sur face/volume ratio at relatively constant surface coverage.