Comparative study of natural rubber and recycled natural rubber as toughening agent in epoxy foam

Abstract

Epoxy foam is one of the common materials used, which being applied especially as the insulator material in electronic purposes and aerospace applications. In order to maximize the potential of natural rubber and recycled natural rubber to be acted as effective toughening agent epoxy foam, the rubber phase must be distributed and dispersed well in the epoxy. In addition, the amount of natural rubber (NR) and recycled natural rubber (rNR) play very important role in influencing the mechanical properties of the epoxy foam. Addition of blowing agent: sodium bicarbonate (NaHCO3) to the epoxy system with NR and rNR as toughening agent have been investigated. The epoxy foam samples were fabricated using mechanical mixing technique. Sodium bicarbonate was selected as blowing agent due to the environmental friendly and low cost concern. While natural rubber and recycled natural rubber controls the toughening effect because epoxy foam is brittle in nature. This research consists of three parts of studies. First, the effect of sodium bicarbonate content, secondly, the effect of natural rubber content and lastly, the effect of recycled natural rubber content on the properties of epoxy foam. Mechanical, physical and morphology properties were done. Sodium bicarbonate content was varied at 5, 10, 15 and 20 phr, respectively. Natural rubber and recycled natural rubber content were varied at 5, 10, 15, 20 and 25 volume percentage (vol %), respectively. The experimental results showed the maximum content of the blowing agent was selected at 20 phr and it gave the highest porosity percentage (%), however it revealed the lowest value in mechanical and density properties. The morphology shows that, at 20 phr sodium bicarbonate content produced the high % of porous structure. As for the second part of study, for natural rubber loading, 10 vol % revealed the optimum value of flexural, fracture toughness, density, porosity % and morphology properties.