| Thermoplastic vulcanizate(TPV)is a kind of material prepared by dynamic vulcanization(DV)process.A large amount of rubber phase(50%-80% wt%)is dispersed in a small amount of resin matrix(50%-20% wt%).Its rubber phase provides TPV elastic properties.The resin phase presents a hard phase at room temperature and can be melted and plasticized by heating,giving TPV excellent processability and reprocessability.As a special thermoplastic elastomer(TPE),TPV has the advantages of excellent processing technology(without the traditional vulcanization process of rubber),low production and management cost and excellent performance,which makes TPV gradually occupy a place in the market and is a "green" material.The macroscopic mechanical properties of materials are the reflection of their internal structure,which includes aggregation structure,molecular chain structure and so on.For polymer materials,especially rubber plastic blend dynamically vulcanized thermoplastic elastomers,their mechanical properties are closely related to internal structure such as crosslinking degree,composition and external conditions such as strain rate and temperature.In this project,Polylactam(PA12)and its modified resin are selected as the resin phase for preparing dynamic vulcanized thermoplastic elastomer and mixed polyurethane(MPU)and its blends are selected as the rubber phase to prepare TPV.This TPV has the characteristics of high strength,excellent heat resistance and non-polar medium resistance.The addition of certain filler and reinforcement system can significantly improve its performance and further reduce the material cost,The product does not need the traditional vulcanization process,simplifies the production process,and the material can be reused.The research contents are as follows:(1)MPU/PA12 TPV was prepared by dynamic vulcanization.The effect of the ratio of rubber to plastic on the properties of TPV was investigated.It was found that when the ratio of MPU/PA12 was 70/30,the TPV had high physical and mechanical properties;The rubber phase MPU in TPV was modified,and the effects of vulcanization and reinforcement system on the properties of TPV were studied.It was found that MPU/PA12 TPV with high properties could be prepared when DCP was 1.2phr and silica was 30 phr.(2)MPU/CM/PA12 TPV was prepared by adding some chlorinated polyethylene(CM)into MPU.The effects of MPU/CM blending ratio,peroxide type and composite curing system on its properties were studied.It was found that when the MPU/CM blending ratio was 70/30,the properties of TPV were improved,and when the curing system was 1.2 phr DCP,the TPV had better physical and mechanical properties,aging resistance and hot oil properties.(3)The resin phase in TPV was modified,and MPU/PA12/416 D TPV,MPU/PA12/PVDF TPV and MPU/CM/PA12/PAM15 TPV were prepared by chemically modified ethylene elastomer(416D),polyvinylidene fluoride(PVDF)and copolymer series nylon(PAM15).The effects of different resin phase and use ratio on the properties of TPV were studied,and the correlation between the properties of "sea and island" phase and its properties was further studied and summarized;The interfacial thickness of TPV modified by different methods was calculated by contact angle method to characterize the effect of compatibility on TPV.Different processing technologies and external loading conditions of MPU/PA12 TPV were studied,including dynamic vulcanization time,dynamic vulcanization shear rate,different strain rate,tensile temperature and repeated processability.It was found that with the extension of dynamic vulcanization time,the intersection degree of rubber increased and the phase inversion of TPV was completed;When the shear rate is 60 rpm,the TPV has a relatively perfect sea island structure;The effects of strain rate and tensile temperature on the properties of TPV were explored;The TPV prepared in this subject has the properties of repeated processing and use. |
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