The influence of pre-compounding techniques and surface modification of nano-silica on the properties of thermoplastic natural rubber

Abstract

Thermoplastic natural rubber (TPNR) nanocomposites based on epoxidized natural rubber (ENR) and polypropylene (PP) blends filled with 2.5 wt% nano-silica (SiO2) were prepared using a two-step compounding process to improve the dispersion of SiO2 in TPNR. The effects of the compounding techniques, i.e., solid pre-compounding and latex pre-compounding processes of SiO2 and ENR, and surface modification of SiO2 on the morphological, mechanical, and thermal properties together with the crystallization behavior of PP phase in ENR/PP blends were demonstrated. Scanning electron microscope (SEM) results showed that latex pre-compounding of SiO2 and ENR gave finer dispersion and distribution of SiO2 particles in the TPNR matrix as compared with the solid pre-compounding technique. Also, the superior mechanical properties and thermal stability of the blends were achieved by using the latex pre-compounding technique. Moreover, surface modification of SiO2 by organosilane was found to enhance crystallization rate and the degree of crystallinity of PP phase in the TPNR, leading to an improvement in the strength and mechanical properties of the ENR/PP blends. These results agree well with the morphological properties that presented a good dispersion and distribution of silane-modified SiO2 particles in the TPNR matrix.

Keywords

• nanocomposites
• nanosilica
• thermoplastic natural rubber
• latex pre-compounding
• solid pre-compounding