Composites of natural rubber, carbon black, and kaolin sodium bicarbonate content for sponge application

Modification of rubber-carbon-kaolin composite with sodium bicarbonate into sponges was carried out through the process of mastication, vulcanization and printing. The main ingredients consisted of natural rubber, carbon black, kaolin and sodium hydrogen carbonate. The research methodology was based on the development of composite rubber-carbon-kaolin by varying the composition of fillers which were kaolin and Sodium Bicarbonate. The results showed that mechanical properties of the modified sponge rubber-carbon-kaolin composite with sodium hydrogen carbonate for the formula B (Kaolin: Calcium Carbonate = 8:38 phr) had specific gravity of 0.51 g/cm3, compression set of 28,05%, tensile strength of 34,46 N/m3 and elongation at break of 212%. Based on the morphological analysis (SEM micrographs), the porosity of the composites was not homogenous. In addition, based on the thermal gravimetric analysis (TGA) there was a decrease in relative mass due to the differences kaolin and Natrium Bicarbonate loading.