Effect of preparation methods and carbon black distribution on mechanical properties of short pineapple leaf fiber-carbon black reinforced natural rubber hybrid composites

The aim of this work is to improve the performance of natural rubber reinforced with a hybrid of pineapple leaf fiber with carbon black. When there are multiple components to be mixed into a rubber matrix, mixing can be carried out in more than one way. Thus, in this study, the effects of preparation method and the resulting carbon black distribution on the mechanical properties of the hybrid composite were evaluated. Pineapple leaf fiber (PALF) and carbon black contents were fixed at 10 parts (by weight) and 30 parts (by weight) per hundred parts of rubber (phr), respectively. In order to improve the dispersion, PALF with rubber was prepared as a masterbatch. Carbon black was added to the compound either as a single portion or as two separate portions, one in the PALF masterbatch and the other in the main mixing step. It was found that, despite using the same final compound formulation, the mixing scheme significantly affected the medium strain region of the vulcanizate stress-strain curve. No stress drop in this strain region was observed for the two-step mixing scheme. Models for composites with different preparation methods are proposed and discussed.