Foamability of Natural Rubber via Microwave Assisted Foaming with Azodicarbonamide (ADC) as Blowing Agent

Abstract

Abstract Utilization of microwave in material processing has attracted significant interest due to its advantages such as rapid and volumetric heating capability. However, the use of microwave in rubbers is usually focused on vulcanization and devulcanization of rubber, but very limited on rubber foaming. Therefore in this study, attempt was made to understand the foaming behavior of natural rubber foam (NRF) via microwave assisted processing using azodicarbonamide (ADC) as the blowing agent. The microwave settings were varied and evaluated in relation to expansion behavior and foam structure of the produced NRF. Three settings were used, i.e. microwave heating only, conventional heating only and third heating was sequential heating with microwave and followed by convection heating. The results indicated that the NR can be foamed via microwave heating in less than six minutes. However good foam structure can be produced by the sequential heating setting between microwave and convection heating. The obtained results demonstrated that microwave can be potentially used as alternative heating to conventional oven heating in production of rubber foams.