Preparation of elastomeric foam having high cell pressure and foaming agent content-independent foam density

The closed-cell natural rubber (NR) foam including bubbles with high gas pressure was produced by controlexpansion method using one step compression molding. In this study, the simultaneously improvement in the rubber modulus and hardness with rubber resilience is reported for first time. The results showed that the expansion ratio andfoam density became constant independent of foaming agent (Azodi bicarbonamide, ADC) content, while the gas pressure inside the bubbles increased by increasing ADC content. Cells with high gas pressure acted as filler and increased mechanical properties. The increase in the ADC content from 1 to 10 phr yielded in a 94%, 55% and 70%increase of the Hardness, Elastic modulus and resilience, respectively. The scanning electron microscopy (SEM) results demonstrated that all the foams had uniform structure and the maximum and minimum cell size (550 and 330 μm) was occurred in the sample with 3 phr and 10 phr of ADC respectively.

Keywords:

Control expansion , Foaming agent , Natural rubber foam , Resilience properties