Structure And Properties Of Functional HDPE/SBR TPV

The Thermoplastic vulcanizate(TPV)based on high density polyethylene(HDPE)/styrene-butadiene rubber(SBR)blends were prepared by dynamic vulcanization.Its mechanical micro-morphology,properties,Mullins effect under compression mode and its reversibility behavior,stress relaxation behavior under compression mode and its reversibility behavior,compression set behavior and its reversibility behavior were studied systematically;moreover,the heat-induced shape memory polymer(HSMP)material based on HDPE/SBR TPV was prepared and the microscopic surface and shape memory behavior were observed,and the effects of weight ratios,deformation temperature,recovery temperature,and compatibilizer on the fixing ratio and recovery ratio of shape memory were researched,and a mechanism of shape memory behavior based HDPE/SBR/SBR TPV was proposed;nonisothermal cold crystallization of pure high density polyethylene(HDPE)and the thermoplastic vulcanizates based on HDPE/styrene-butadiene rubber(SBR)were investigated by differential scanning calorimetry(DSC),the Avrami,Ozawa and Mo methods were carried out to describe the process of nonisothermal crystallization;finally,metallographic sandpapers were used as a template to prepare a molded TPV film with hydrophobic property.The influence of abrasive particle size on the hydrophobic properties of molded TPV film and the stability of molded TPV film were studied systematically;moreover,a new oil-water separating equipment was constructed which could achieve continuous oil-water operation.The influence of different film gap and relative vacuum degree on the oil-water separation was researched and the microstructure of the surface of the molded TPV film was observed and mechanism of oil-water separation behavior was proposed.The main results were shown as below:(1)With the increasing HDPE content in HDPE/SBR TPV,the characteristics of stress-strain curve had changed from“soft and tough”to“hard and tough”;the stress relaxation of the HDPE/SBR TPV under compression mode was mainly determined by the HDPE phase,while the SBR dispersed phase only had a certain influence on it.The hardness and elongation at break of the HDPE/ethylene-octene copolymer(POE)/SBR TPV were lower than that of the HDPE/SBR TPV.It could be found that the HDPE/POE/SBR TPV had relatively lower internal friction loss(tan?)and residual deformation than that of the HDPE/SBR TPV from the results of Mullins effect,indicating the improvement of elasticity.Increasing the number of compression cycles,the instantaneous residual deformation was increased while the maximum stress and tan?were decreased.The maximum compression stress reversibility of TPV during the second compression was improved with the increasing of heat treatment temperature,and the best stress reversibility was achieved at 130?.The microscopic phase structure study showed that the particles size of SBR vulcanizates in HDPE/SBR TPV was 5-10?m,which was evenly dispersed in the surface of etched samples and the fracture surfaces of HDPE/POE/SBR TPV were relatively smooth,indicating the existence of POE in the TPV can improve its elastic reversibility.(2)The HDPE/SBR TPV samples have obvious shape memory effect under different temperatures.The tensile samples of TPV showed the obvious orientation microstructure,and the existence of styrene-based block copolymer(SBS)could improve the shape memory property of HDPE/SBR TPV remarkably.When the fixed temperature and recovery temperature were 120?and the SBS dosage was 6 phr,the shape memory property of HDPE/SBR TPV was best,the SF and SR reached 90.6%and 90.4%respectively.(3)The Avrami and Mo methods could precisely describe the process of nonisothermal crystallization of pure HDPE and the HDPE/SBR TPV.However,the Ozawa method could not suitably describe the process of nonisothermal crystallization due to the graph obtained from the Ozawa equation does not match the anticipation.For both pure HDPE and HDPE/SBR TPV,the overall nonisothermal cold crystallization rates increased with the increasing cooling rate.Moreover,the HDPE/SBR TPV showed a higher initial crystallization temperature(T_o)and crystallization termination temperature(T_c),and a lower crystallization half time(t_1/2)co MPared with that of pure HDPE at the same cooling rate,indicating the nucleating effect of SBR phase.(4)When the metallographic sandpaper with W14 type was used as template,the water contact angle of the molded TPV surface was 159.2°and the rolling angle was7.2°.When the film gap of the molded TPV film in the oil-water separating equipment was 50?m and the relative vacuum was 3 KPa,for the oil-water separating effect was remarkable and the separation efficiency.