Approaches toward High Resilience Rubber Foams: Morphology–Mechanics–Thermodynamics Relationships

Abstract

Natural rubber foam (NRF) products are frequently required in high resilience or high shape recoverability applications, which is in contrast to the fundamental nature of NRF. This study aims to improve NRF properties, such as recovery, by increasing the amount of vulcanizing chemicals (Vc) and adding cassava starch (Cs). Interestingly, increasing the amount of Vc and Cs improves mechanical properties and shape recoverability of NRF although the morphology of NRF with various concentrations of Cs is similar. The ratio of internal energy to the compression force is almost constant with various amounts of Vc and Cs because the degree of freedom of the rubber chains remains stable. NRF possesses better compression strength and shape recoverability with increasing amount of Vc (optimum of 16 phr) and Cs (optimum of 8 phr). Cassava starch is discovered as an attractive filler in comparison to traditional NRF fillers, such as charcoal and silica, due to its relatively low density.