Yield behavior of polypropylene filled with CaC0₃ and Mg(OH)₂. I: “Zero” interfacial adhesion

The composition dependence of tensile yield stress (σ yc ), and the effects of filler particle shape and surface treatment were investigated for polypropylene (PP) filled with CaCO 3 or with Mg(OH) 2 . Poor adhesion between PP and CaCO 3 accounted for a decrease of σ yc with increasing σ f . In spite of the poor adhesion between PP and Mg(OH) 2 , σ yc either slowly decreased with increasing V f or remained constant up to V f = 0.25. Surface treatment of the fillers facilitated better dispersion in PP. On the other hand, σ yc was reduced due to the lower thermodynamic work of adhesion ( W A ). The semiempirical one‐parameter equation proposed by Turczanyi, Pukanszky, and Tüdüs (TPT) was considered plausible and was employed in the study of the effects of matrix‐filler interaction.