Impact responses of an open-cell natural rubber foam impregnated with shear thickening fluid

Abstract

This research aims to investigate the impact responses of an impact absorbing material prepared from natural rubber (NR). Shear thickening fluid (STF) was developed in order to improve compatibility, and impact response capability of a NR foam. The material was prepared by impregnating NR foam with STF (30 wt% nanosilica with 10 nm). The obtained material is soft under normal circumstances, but immediately stiff when undergoing sudden impact before softening again. The effects of foam densities (0.098, 0.15, 0.24 g/cm3), STF contents (10, 20, 30 vol%), and fluid filling techniques were investigated. Experimental results show that the absorbed force tends to increase by increasing the foam density and the fluid content. Impact absorption capability of the proposed STF (STFA)/NR foam is higher than that of the conventional STF (STF0)/NR foam. In other words, STFA can improve the impact responses of the material providing comparable results with the commercial kneepad, which has the dilatant behavior.