Study On Preparation And Properties Of POE/PP Thermoplastic Elastomer By Dynamic Vulcanization

In this paper, the new polyolefin elastomer POE and thermoplastic Polypropylene were selected as basic material, dicumyl peroxide (DCP) /sulfur as curing system, carbon black, talc, nano-Kaolin, nano-CaCO3 as reinforcements, and the paraffin oil, naphthenic oil as plasticizers. The high performance of POE/PP thermoplastic elastomer was gained by dynamic vulcanization. Effect of processing parameters on properties was discussed. Besides, the comprehensive properties and microstructure of the TPV were investigated.The POE/PP blends was prepared in Haake torque rheometer and the physical properties of the blends was investigated. Results showed that the properties of blends were influenced by different feeding method obviously. It was proved that the method of pre-mixing was better than the method of pre-vulcanization. The method of pre-mixing could shorten vulcanization time and avoid the degradation of PP based on the premise that POE was fully crosslinked, so the performances of blends were better. By analyzing the effect of processing parameters on properties of the blends, the optimal processing condition was that temperature was 180°C,rotation speed was 50 r·min-1 and blending time was 11-13min.The influences of the DCP content as the curing agent on properties were discussed. For the DCP crosslinking system, the melt flow rate was increased and mechanical properties of POE/PP blends were decreased. Crystalline morphology and characteristics of PP matrix was observed by polarizing microscope and Differential Scanning Calorimeter (DSC), results showed that the crystalline size became larger, degree of crystallinity and melting point were upgrading when the PP relative molecular mass was decreased. Compared with TAIC, sulfur was more effective crosslinking agent in peroxide curing system. The properties of blends were improved significantly when the DCP content was 2 phr and the sulfur content was 0.2 phr. For example, the tensile strength could be enhanced with amplitude of 60%, and the amplitude of elongation at break exceeded 70%. The Scanning Electronic Microscopy(SEM) photographs showed clearly that the blending system of POE/PP was typical"sea-island"two phased structure, in which POE as dispersing phase dispersed evently in the matrix of PP.Carbon black, Talc, nano-Kaolin and nano-CaCO3 were used to reinforce the POE/PP dynamic vulcanizates respectively. It was found that these four systems still maintained the high mechanical properties after reprocessing. The rheological experiment showed that the shear viscosity of blends to the shear rate was very sensitivity, especially the POE/PP/talc system. Compared with other reinforcements, the POE/PP/carbon black thermoplastic elastomer has the best comprehensive properties, particularly the anti-weathering. When the carbon black content was 20 phr, the mechanical properties were optimal, and the percentage change of tensile strength was only 7.76% after weathering aging while the other three systems reached 28%. The SEM photographs showed that the carbon black dispersed in the matrix resin as nano-particle, so the blends has the good performances.The paraffin oil and naphthenic oil were used as plasticizer in order to reduce the hardness of the POE/PP thermoplastic elastomer. Results showed that the paraffin oil was more preferable plasticizer than naphthenic oil. When paraffin oil content was 30 phr, paraffin oil could decrease the hardness of POE/PP/carbon black thermoplastic elastomer markedly and did not affect other properties.