| In this paper,high performance MVQ/TPU thermoplastic vulcanizates were prepared by dynamic vulcanization technology using a mixture of methyl vinyl silicone rubber(MVQ)and thermoplastic polyurethane(TPU)with peroxide as vulcanization system.The effects of dynamic curing process,curing system,type and dosage of compatibilizer on the rheological properties,mechanical properties,thermal stability,microstructure and dynamic mechanical properties of MVQ/TPU TPV were studied.By studying the dynamic vulcanization process of MVQ/TPU TPV,the optimum process conditions and parameters for the preparation of TPV by using HAAKE torque rheometer were obtained.According to the mechanical properties and the phase structure of TPV,the optimal dynamic vulcanization process conditions were selected as follows: rubber/plastic ratio 40/60,blending temperature 180 ?,rotor speed 80 r/min,dynamic vulcanization time 10 min,molding temperature 190 ?.Different dynamic curing methods had different effects on the properties of MVQ/TPU TPV systems.The M3 preparation method had the most uniform phase structure and the strongest crosslinking network structure.The influence of the type and amount of peroxide crosslinking agent on the mechanical properties,thermal stability,micromorphology and melt flowability was systematically investigated.The results showed that the mechanical properties of the TPVs vulcanized by 2,5-dimethyl-2,5-di(tert-butyl peroxy)hexane(DBPH)first increased and then decreased with increasing the peroxide amount,while for dicumyl peroxide(DCP)vulcanizing system the mechanical properties slowly increased.Besides,the comprehensive mechanical properties vulcanized by DBPH were better than those of DCP group.The results of the thermogravimetric analysis showed that the TPVs vulcanized by DBPH had better heat stability,corresponding to the excellent thermooxidative aging performance and the 38% increase in tensile strength after aging.In addition,the MVQ rubber particles showed better dispersing performance for DBPH vulcanizing system.The melt flow rate(MFR)of the TPVs showed a linear relationship with increasing DBPH dosage and became worse after the amount of crosslinking agent exceeded 1.5 phr.By comprehensive comparison,the TPVs have better performance when use peroxide DBPH as the crosslinking agent and the dosage is 1.5 phr.The mechanical properties of TPV decreased after the addition of assistant crosslinker,and the uniformity of phase distribution of TPV system was slightly reduced.However,the thermal stability of MVQ/TPU TPV system could be improved by adding assistant crosslinker,and the effect of TAIC was more obvious.After the secondary vulcanization,the mechanical properties of the TPV system were basically unchanged,indicating that the TPV system does not need the two-stage vulcanization process,the processing and molding process is more simple.The results of the study on the TPV compatible system showed that: With the increase of the amount of compatibilizer,the mechanical properties of TPV generally showed a trend of first increase and then decrease,and the best mechanical properties of TPV were obtained when POE-g-MAH was used as compatibilizer.TPV with different type and dosage of compatibilizer had good thermal oxygen aging performance,and compatibilizer can improve the thermal stability of TPU phase in TPV.DMA and SEM results showed that the three compatibilizers can improve the compatibility of rubber and plastic two-phase in TPV system.When POE-G-MAH was selected as compatibilizer,the glass transition temperature of the two phases in TPV was the closest,and the interface of the two phases in the TPV section was the most fuzzy,indicating that POE-G-MAH had the best compatibilization effect on TPV,and the compatibilization effect was the best when the dosage is 6 parts.MVQ/TPU TPV had excellent reproducible processing properties.With the increase of repetitions,the mechanical properties of TPV tend to increase. |
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