Microcellular foaming and mechanical properties of iPPF reinforced PPR composites

Abstract Fibers are often used to improve the mechanical properties of the polymers. Herein, a facile self-reinforcement method of adding isotactic polypropylene fiber (iPPF) to polypropylene random copolymer (PPR) was developed to enhance its foamability and mechanical properties. Rheological, foaming, crystallization behaviors and mechanical properties of the blends were studied. Elastic modulus, viscous modulus and complex viscosity increase with increasing iPPF content. Due to enhanced viscoelasticity, comparatively uniform PPR-iPPF cells were fabricated. Cell density of PPR-30 iPPF was increased by two orders of magnitude, compared to that of pure PPR, because of the enhanced melt strength and heterogeneous nucleation effects. Compared to solid PPR, the impact strength of foamed PPR-10iPPF was increased by 170%. For both solid and foamed samples, the tensile strength was increased with increasing of iPPF content. However, the tensile strength of the foamed sample is lower than that of solid sample, regardless of the iPPF content.