Crystallization Behavior and Mechanical Properties of Nanosilica-Reinforced Isotactic Polypropylene Composites

Abstract

Abstract Two different types of inorganic silica fillers, nano-silica powder (NSP) and colloidal silica sol (CSS) were added into isotactic polypropylene (iPP) with low silica content (0.2 wt%) and the influence of the two silica fillers on the crystallization behavior and mechanical properties of iPP were investigated. Differential scanning calorimeter (DSC) results showed that the crystallization temperature of iPP with CSS and NSP were increased by 4.1 °C, and 2.4 °C, respectively. The tensile strength, flexural strength, and izod impact strength of iPP/CSS (33.75 MPa, 33.04 MPa, and 4.80 kJ/m2) were higher than that of iPP/NSP (32.09 MPa, 32.27 MPa, and 4.25 kJ/m2). In addition, the haze value of iPP/CSS was decreased from 37.6 % to 27.6 %, which was 4.7 % lower than that of iPP/NSP (32.3 %). The better performance of CSS as ascribed to its better dispersion ability in iPP matrix than NSP, and it was verified by scanning electron micrograph (SEM) and transmission electron microscope (TEM). Overall, these results indicated that inorganic silica sols had a potential application in the nanoparticle-reinforced composites field.