Thermoplastic natural rubber based on oil extended NR and HDPE blends: Blend compatibilizer, phase inversion composition and mechanical properties

The oil extended natural rubber (OENR) and HDPE blends with different rubber-plastic components (i.e., OENR/HDPE = 0/100, 20/80, 30/70, 40/60, 50/50, 60/40, 70130, 80/20 and 100/0) were prepared by a melt mixing process at 160 degrees C. Effect of blend compatibilizer (i.e., phenolic modified polyethylene, PhHRJ-PE) and proportions of OENR/HDPE in the blend on theological, tensile, morphological and hardness properties were investigated. It was found that the blend with compatibilizer exhibited higher flow and viscosity curves as well as mechanical properties in terms of 100% modulus, tensile strength and elongation at break. SEM micrographs and theological properties indicated that the blends of CENR/HDPE are two-phase systems (i.e., separation of rubber and plastic phases). The component with the lower proportion was found to be a dispersed phase in the major continuous matrix phase. Co-continuous phase morphology was also observed in the blend with the blend ratios of OENR/HDPE = 50/50 and 60/40, where the materials behave as thermoplastic elastomers. The predictions using various models found that the phase inversion composition was in agreement with the experimental results. It was also found that the tensile strength, elongation at break, tension set and hardness properties were strongly dependent on the blend proportions. (C) 2008 Elsevier Ltd. All rights reserved.