Predicting the Elastic Modulus of Hybrid Fibre Reinforced Thermoplastics

Hybrid fibre reinforced thermoplastics (containing more than one type of fibre) offer several design possibilities that do not exist with single fibre reinforced systems. Although there are extensive experimental data available in the literature on a variety of hybrid systems, a reliable and simple analytical model to predict the stiffness of these composites is not available. In this study, a modification of the hybrid rule of mixtures equation is developed to determine the stiffness properties of hybrid composites. Experimental data from single fibre reinforced thermoplastics forms the basis of the modification. Combinations of E-glass, hemp and hardwood flour were blended into high-density polyethylene in total fibre loadings of 10 to 60wt% to produce hybrid composites. The density and Young's modulus of the hybrid composites fell between the extreme values obtained for the single fibre composites. The modified rule of hybrid mixtures equation was found to adequately predict the tensile modulus of the hybrid composites.