Preparation and characterization of natural rubber foams: Effects of foaming temperature and carbon black content

The influence of the foaming temperature and carbon black content on the cure behavior and mechanical properties of natural rubber foams was investigated at five temperature zones by 5 degrees C interval and different feeding ratios of the carbon black. The physical properties of the foamed NRs were then measured as a function of the foaming temperature and carbon black content, respectively. The optimal temperature for vulcanization and foaming of NRs in this study was considered to be 165 degrees C where density of the foamed NR is lower than that at other four temperature zones. The thickness of each of the struts formed within the rubber matrix decreased with the increasing foaming temperature, while it increased with the increasing carbon black content, supporting the density characteristics. The tensile properties of the foamed NRs such as tensile strength, tear strength and modulus gradually increased with the increasing and carbon black content, while elongation at break decreased.