| Silicone thermoplastic vulcanizate(TPSiV)is a new type of special thermoplastic elastomer with a large number of silicone rubber(VSR)phases dispersed as a dispersed phase in a small amount of continuous thermoplastic matrix after dynamic vulcanization(DV).And VSR / polyurethane(TPU)TPSiV is widely used in special fields such as wearable devices and medical equipment with strict requirements.Because it has the advantages of VSR's low hardness,high and low temperature resistance,chemical resistance,high elasticity,and outstanding physical and mechanical strength and good biocompatibility of TPU.So far,only Dow Corning of the United States has industrialized TPSiV internationally,while domestic research remains at the laboratory research stage.This article first studied the compatibilization problems of VSR / TPU simple blends,and then used 2,5-dimethyl-2,5 bis(t-butyl peroxide)hexane(DBPH)peroxide vulcanization system,silicon The hydrogen(Si-H)/ platinum(Pt)catalyst sulfurization system was used to prepare VSR / TPU TPSiV and its microphase structure and properties were studied.Finally,the industrial development of VSR / TPU TPSiV based on peroxide(DBPH)vulcanization system was studied.The following important conclusions have been drawn from the above research work:(1)The rheological performance of different brands of VSR and TPU was tested by capillary rheometer,and the brands of VSR 110-1 and TPU 9380 AU were determined.(2)The compatibilizing effects of different amounts of self-made compatibilizer PDMS-PU and commercial EMA on VSR / TPU simple blends of were studied.The results show that both PDMS-PU and EMA have a capacity-enhancing effect on VSR / TPU simple blends,and PDMS-PU has a better capacity-enhancing effect than EMA.When the amount of PDMS-PU is 4 phr,the capacity expansion effect is the best.(3)For the preparation of VSR / TPU TPSiV with peroxide(DBPH)vulcanization system,we studied the effect of the inhibitor 4-hydroxy2,2,6,6-tetramethylpiperidine oxygen(TEMPO)on vulcanization process and performance of VSR/TPU system,and revealed its mechanism of action.When the amount of TEMPO is 0.3 phr,the scorch period(about 2 min)and the normal vulcanization time are prolonged,the crosslinking rate of VSR is slowed,and the mechanical properties of the system are better.Finally,the effects of rotation speed and rubber-plastic ratio on the phase and performance of the dynamically vulcanized VSR / TPU system were studied.The results showed that the VSR / TPU system with a rotation speed of 110 rpm and a rubber-plastic ratio of 50/50 reversed,and the VSR was fine(about 150 nm),and its comprehensive performance basically meets the requirements of TPSiV performance indicators;the higher the rubber-plastic ratio,the more difficult it is for the system to reverse.The VSR / TPU system with rubber-plastic ratio 60/40,70/30 has not reversed,and its comprehensive performance is very poor.(4)Based on the Si-H / Pt vulcanization system,we adopt a new method(that is,VSR / Si-H / TPU is pre-mixed at high temperature in Hakke,and then the inhibitor diallyl maleate DAM / Pt is added in the cold roll.And finally dynamic vulcanization in Hakke)successfully prepared VSR / TPU TPSiV.Studies have shown that the addition of DAM significantly inhibits the vulcanization of VSR at room temperature,and solves the problem of the premature and rapid cross-linking of VSR that is difficult to control due to the presence of Pt at room temperature.The VSR / TPU TPSiV successfully prepared by the new method has a finer phase state(the average size of the VSR phase domain is about 5um)and good dispersibility,which gives it outstanding overall performance.Its performance fully meets the performance indicators of TPSiV and is far superior to Oxide curing system.(5)Research on the industrialization demonstration of preparing high-performance VSR / TPU TPSiV shows that its performance basically meets the TPSiV industrialization performance index. |
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