Evaluation of azodicarbonamide (ADC) on density, expansion ratio and closed cell properties of natural rubber foam

Abstract Natural rubber foams were made with a one-step foaming process, the effect of density, expansion ratio, and closed-cell properties via microscope were investigated. This research aims to investigate novel half vulcanization and full vulcanization process with three various blowing agents by compression moulding to fabricate natural rubber and carbon black foams. Closed cells of natural rubber used as shoe soles were formed by azodicarbonamide (ADC) and organic blowing agents. The experimental design used three blowing agent of Azodicarbonamide (ADC) A, B C, and control. The data analysis for images was performed in ImageJ software to get more quantitative results. Experimental data were created to perform a full (AF; BF; and CF) and half vulcanization (AH; BH; and CH) process. The different structure model based on digital microscope images was shown. The AH, BH, and CH with half vulcanisation process revealed a higher expansion ratio and cell number value. The microscope showed that rubber foam with the highest expansion ratio and cell number has a more homogenous structure with more cell connection of AH, causing a lower density value of 0.6480. In addition, AH and CH with ADC showed higher values than BH with an organic blowing agent, respectively.