Mechanical properties of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Mechanical properties of the isotactic‐polypropylene/glass bead (iPP/GB) and iPP/wollastonite (iPP/W) composites modified with thermoplastic elastomers, the poly(styrene‐ b ‐ethylene‐ co ‐butylene‐ b ‐styrene) copolymer (SEBS) and corresponding block copolymer grafted with maleic anhydride (SEBS‐ g ‐MA), were investigated. An increase in toughness of iPP with the elastomers was associated with a decrease in rigidity and strength. Mechanical performance of iPP increased more with acicular W than with spherical GB due to reinforcing effect of W. Comparing the (iPP/GB)/SEBS and (iPP/W)/SEBS composites having the separate microstructure, strength and toughness values of the iPP/GB and iPP/W composites increased more with SEBS‐ g ‐MA at the expense of rigidity due to the core‐shell microstructure with strong interfacial adhesion. Moreover, the iPP/W composite exhibited superior mechanical performance with 2.5 and 5 vol% of SEBS‐ g ‐MA because of a positive synergy between the core‐shell microstructure and reinforcing effect of acicular W. The extended models revealed that the elastomer and filler particles in the (iPP/GB)/SEBS and (iPP/W)/SEBS composites acted individually due to the separate microstructure. However, the rigid GB and W particles encapsulated with the thick elastomer interlayer ( R 0 / R 1 = 0.91) in the (iPP/GB)/SEBS‐ g ‐MA and (iPP/W)/SEBS‐ g ‐MA composites acted like neither big elastomer particles nor like individual rigid particles, inferring more complicated failure mechanisms in the core‐shell composites. POLYM. COMPOS., 31:1285–1308, 2010. © 2010 Society of Plastics Engineers