Preparation,Structure And Properties Of High Somatosensory Compatible Silicone Thermoplastic Vulcanizate(TPV)

Silicone rubber thermoplastic vulcanizates(SiTPVs)are a kind of thermoplastic silicone elastomer,which have a 'sea-island' type morphology that crosslinked silicone rubber particles dispersed in thermoplastic phase.Compared with general TPV,they have more superior properties.Thus,they are called 'super TPV'.Silicone rubber(SiR)/thermoplastic polyurethane(TPU)TPV provides a unique silky soft touch feel and good coating performance.They are used widely in the field of wearable smart devices.In this paper,we analyze the structure and performance of commercial SiR/TPU TPV products.Then,we selected suitable raw materials.The problem of compatibility of SiR/TPU blend was solved by introducing a compatibilizer.After that,SiR/TPU TPV was prepared and SiR was cross-linked by using organic peroxides and addition reaction respectively,and the performance test was conducted.The main conclusions are as follows:(1)Commercial SiR/TPU TPV is composed of SiR,TPU and fillers,where the rubber phase is methyl vinyl silicone rubber,the plastic phase is polyether thermoplastic polyurethane,and the fillers include CaCO3,MgO and SiO2.Also,the mass ratio of SiR,TPU and filler is about 20:60:20.The product has a fine phase state and good performance.The particle size of the dispersed phase silicon rubber is 200?500 nm.The tensile strength and elongation at break are 4.9 MPa and 320%respectively.And the compression set(23?×22h)is 44%.(2)The silicone oil polybutadiene polyurethane copolymer(PDMS-PB-PU)compatibilized SiR/TPU blends have achieved good results.The optimum concentration is found to be 10 phr of PDMS-PB-PU,in which the mass ratio of SiR:TPU is 30:70.The domain size is reduced from 1.0?m to 0.2 ?m.Correspondingly,the tensile strength of SiR/TPU blends increases from 6.6 MPa to 11.0 MPa.(3)The problem of peroxide crosslinking TPU is solved by a preparation method that the SiR is firstly premixed with organic peroxide at room temperature,then the mixture of the SiR,TPU and other additives are simultaneously melt mixed and dynamically vulcanized.SiR/TPU TPV is successfully prepared.However,it has a rough phase and poor performance.The SiR particle size is 3?30 ?m.The sample with the best performance has a tensile strength of 2.5 MPa,an elongation at break of 260%,and the compression set(23?×22h)of 37%.(4)SiR/TPU TPV was prepared by addition vulcanization.And the problem of premature crosslinking of SiR in addition system was successfully solved by adding acetylene alcohol inhibitor.Through the double premixed dynamic vulcanization process,the problem of TPU poisoning Pt catalyst was solved.The SiR/TPU TPV under this system has a fine morphology and good performance.The particle size of SiR is 1?4 ?m and the sample has a tensile strength of 3.4 MPa,an elongation at break of 253%,and the compression set(23?×22h)of 20%.