Effects of beta-nucleating agent and mineral fillers on mechanical properties of PP/EPR blends

Abstract

The effect of nucleating agents (0.001 wt% bicomponent of calcium stearate and pimelic acid, Ca-Pim, and 0.001 wt% bicomponent of calcium stearate and suberic acid, Ca-Sub) and fillers (kaolin and CaCO[subscript 3]) on beta-crystalline in PP/EPR blend were investigated by WAXD measurement. Results showed that only Ca-Pim promoted Beta-crystalline. For the fillers, it was found that 5-15 wt% of calcium carbonate promoted beta-crystalline and improved tensile and flexural moduli. Therefore, both Ca-Pim and CaCO[subscript 3] were simultaneously added into the PP/EPR blend in order to improve its Izod impact, tensile modulus and flexural modulus. It was found that the composite containing 0.001 wt% Ca-Pim and 5 wt% nano-CaCO[subscript 3] had the highest impact strength and high tensile and flexural moduli. From WAXD measurement, the k-value was about 0.3, higher than that of CaCO[subscript 3] without Ca-Pim. It indicated that both Ca-Pim and CaCO[subscript 3] additively promoted beta-crystallization. The beta-crystalline formation was also confirmed by DSC which exhibited an endothermic melting peak at 153 degree celsius. The effect of isothemal crystallization of Ca-Pim and CaCO[subscript 3] at 130 degree Celsius on beta-crystalline, thermal properties and spherulitic structure was investigated. The results showed k-value of 0.001wt% Ca-Pim and 10 wt% nano-CaCO[subscript 3] wt was 1.0, indicating that beta-crystalline occurred completely.