Influence of Processing Oil and Plasticizer on Properties of ENR-25/TPU Simple Blends

Abstract

Thermoplastic natural rubber (TPNR) based on blending of thermoplastic polyurethane (TPU) and epoxidized natural rubber with 25 mol % epoxide (ENR-25) was prepared by simple blend technique. Influence of different types of plasticizer and processing oil (i.e., DOP, TDAE oil and Paraffinic oil) with a fixed loading level of 20 phr was investigated. The main aim was to improve elasticity and lowering the hardness of the blends. It was found that an incorporation of processing oil and plasticizer caused decreasing of mixing torque, mixing temperature, and mechanical properties in terms of tensile strength, and hardness. This is attributed to diffusion of oil or plasticizer molecules into ENR and TPU phases. The oil and plasticizer typically acts as lubricant to promote the ease of flow and influence on various properties. It was also found that an incorporation of processing oil and plasticizer caused decreasing of glass transition temperature (Tg) of rubber and TPU phases, tension set value and Tan δ which refer to greater rubber elasticity and tendency to recover to original shape after prolonged extension. Additionally, the blend with DOP exhibited superior mechanical and other related properties than those of the blends with TDAE oil and paraffinic oil, respectively.