Preparation and balanced mechanical properties of solid and foamed isotactic polypropylene/SEBS composites

This study presents a self-designed foaming apparatus and routes to manufacture foamed isotactic polypropylene (iPP) blends with uniform and dense cells, using styrene-ethylene-butadiene-styrene (SEBS) block copolymer as toughening additive. The addition of SEBS can clearly enhance the impact strength of solid iPP, iPP blends with a 20 wt% SEBS has obtained high notched impact strength of 75 kJ/m(2), which is ca. 16 times larger than that of neat iPP. Relatively fine microcellular iPP-SEBS foams with the average cell size of several micrometers, and the cell density of 10(9) cells/cm(3) were fabricated using a batch foaming procedure. Moreover, using our self-designed mold and compression foaming method, iPP-SEBS foams with balanced mechanical properties were produced. With the increasing of SEBS, tensile strength and flexural strength were slightly decreased, but the impact strength was increased clearly. The balanced mechanical properties between stiffness and toughness were achieved after compression foaming.

Automated summary

This study introduces a self-designed foaming apparatus and methods to manufacture foamed isotactic polypropylene (iPP) blends with enhanced impact strength using styrene-ethylene-butadiene-styrene (SEBS) block copolymer as a toughening additive. The addition of SEBS increases notched impact strength significantly while maintaining a balance between stiffness and toughness in the produced iPP-SEBS foams. The foams exhibit fine microcellular structures with high cell density, fabricated through a batch foaming procedure and compression foaming method.