Investigation On Dynamically Vulcanized Thermoplastic Elastomer Of CM/EVA

Thermoplastic vulcanizates(TPV) was widely used for its simple processing method and the excellent performance, this paper prepared TPV of chlorinated polyethylene rubber(CM)/ethylene-vinyl acetate copolymer(EVA) in the methed of dynamic vulcanization, studied the compatibility between CM and EVA, dynamic vulcanization technology, rubber and plastic ratio, strengthen system and the flame retardant system through differential scanning calorimetry(DSC), infrared spectroscopy(FTIR), rubber processing analyzer(RPA) and scanning electron microscope(SEM) and other methods, which have a great influence on the physical and mechanical properties, mechanical properties, rheological properties, microstructuretested the physical and mechanical properties, dynamic mechanical properties, rheological properties, microstructure and the flame retardant performance What we have done aimed to preparae a kind TPV with a good flame retardant performance and repeatable processing property and enlarge its application area.(1) Studied the compatibility between CM and EVA,the result of DSC showed that the glass transition temperature(Tg) of CM/EVA was between CM and EVA,the compatibility between CM and EVA was good; the characteristic peak of CM and EVA in the FTIR spectra shifted, it showed that a certain extent reaction between CM and EVA happened; CM, EVA and CM/EVA blends showed "shear thinning" behavior with the increase of shear rate, the viscosity was basically identical at high shear rate,.(2)Investigated the influence of dynamic vulcanization process on CM/EVA blends’properties and microstructure, choosed the most appropriate process:the initial processing temperature was 150℃, mixing speed was 60r/min, dynamic vulcanization time was 13min, rubber and plastic ratio was 60/40. The microscopic morphology of TPV was "sea-ialand structure", the size of rubber particles was about 1μm. After re-mixing experiments of five times, the elongation at break maintained 95%, showed that the TPV had a good repeatable processability.(3)Optimized vulcanization system and strengthen system, the results showed that triazole 2 thiol ammonium salt (FSH) used as vulcanizer, rubber particle size and distribution were uniform, tensile strength was 11.13MPa, presented the best mechanical properties; selected high density polyethylene (HDPE) and carbon black strengthened TPV, when the ratio of CM/EVA/HDPE/carbon black was 60/25/15/12,the tensile strength reached 12.01MPa, elongation at break 301%, TPV presented the best performance.(4) Studied the flame retardant of TPVwith expandable graphite (EG), ammonium polyphosphate (APP), the results showed that EG particle size increasesd to 75μm, TPV’s limit oxygen index (LOI) increased to 34.2%; EG dosage increased to 40% of plastic, TPV’s LOI 33.8%, UL-94 V-0 level, the residual carbon content increased; EG/APP ratio was 3/1,TPV’s tensile strength was 11.82MPa, LOI 31.8%, UL-94 V-0 level.