Optimization of physical and mechanical properties of glycerol - modified natural rubber/starch - filled carbon black composites using two level factorial design

This study was carried out to develop statistical models of formulation parameters for physical and mechanical properties of natural rubber/starch composites using a 22 full factorial central composite design via a response surface methodology. It was to measure the significance and interaction of two identified formulation variables, namely, carbon black (X-1) as the filler and glycerol (X-2) as the processing oil. The factors are optimized to achieve maximum cure characteristics, rebound resilience and tensile strength. The composites were prepared by melt compounding process using a Haake internal mixer at a constant temperature and rotor speed of 60 degrees C and 60 rpm. Through the use of regression models that were developed for the quadratic model, a maximum rebound resilience of 71% and tensile strength of 22.57 MPa was obtained for a carbon black loading of 50 phr and a glycerol loading of 7%.