Mechanical properties of HDPE/CaCO3/ethylene-octene copolymer composites

Abstract

Effects of nano-sized CaCO3 particles and Ethylene-Octene Copolymer (EOC) contents on mechanical properties and compatibility of HDPE/CaCO3/EOC composites were studied in this research. The results showed that the composites containing 20% loading of 60-nm CaCO3 particles without a surface treatment caused the particle agglomeration. Its poor dispersion in the polymer matrix lowered the Izod impact strength by 37.7% and yield strength by 2.3% but increased breaking strength and tensile modulus of the composites as compared to the neat HDPE. The surface pre-treatment of CaCO3 with the titanate coupling agent KR TTS or KR 12 decreased the CaCO3 particle agglomeration to give better particle dispersion as observed in the SEM micrographs. The KR TTS or KR 12 at 0.8% weight loading of CaCO3 increased the Izod impact strength by 29.6% and 31.4%, respectively, in comparison with the untreated composites. Tensile modulus was still lower than that of the neat HDPE but the yield strength was increased. The use of EOC markedly improved the Izod impact strength of the HDPE composites especially when the pre-treated CaCO3 particles with 0.8% weight of KR TTS or KR 12 was used in combination with EOC at 2% loading, a higher Izod impact strength when compared to the neat HDPE was obtained. When the polymer composite contains the untreated CaCO3, a 6% EOC loading must be incorporated to achieve the higher Izod impact strength as compared to the neat HDPE.