Preparation And Properties Of Polyurethane/Silicone Rubber Thermoplastic Elastomer Through Dynamic Vulcanization

Thermoplastic elastomer (TPSiV) based on polyurethane (TPU) and silicone rubber have been prepared through dynamic vulcanization using Haake torque rheometer. This article mainly studies the effect of the processing technology, crosslinking agent content, catalyst agent content and curing rate on the mechanical properties of the thermoplastic elastomer; discusses the phase inversion point under different blend ratio, dynamic vulcanization processing and polyurethane materials with different viscosity. The effect of two different compatibilizers on the properties and structure of TPU/VSR binary compound and TPV is tested. The results are as follows:1. Compared with the contribution of methyltriethoxysilane grafting ethylene-vinyl acetate copolymer (EVA-A151), the segmented polyurethane modified by a hydroxyalkyl functional polydimethylsiloxane (PDMS) (Si-PU) is more effective for the improvement of the mechanical properties for TPU/VSR binary blend.2. For binary blend, the phase inversion happens with 50% content of silicone rubber. It can be reduced by increase of the viscosity of TPU. For TPSiV, the point of phase inversion is increased to 60%. During the dynamic vulcanization, the phase transition occurs within 1min, and during this stage, the silicone rubber transforms from initial continuous phase to the dispersed phase. Then, the particle size of cured rubber is gradually decreased until 5min.3. The processing technology during dynamic vulcanization influences the properties of TPU/VSR TPV. Under the rotor speed of 70rad/min, curing time of 5min and curing temperature of 190℃, the elastomer shows best performance.4. The crosslinking density of VSR can be influenced by content of crosslinking agent (hydrogen silicone oil) (Si-H) and catalyst agent (platinum complex), which affects the final mechanical properties of TPSiV. When the Si-H concentration is 1.65 phr and the catalyst content is 0.16 phr, the tensile strength, elongation at break and tear strength of TPSiV are 12.36MPa,745.8% and 30.16KN/m, respectively. For TPSiV, when the Si-PU content is 4.5 phr, the tensile strength, elongation at break and tear strength are increased by 12.5%,26.35% and 5.37%, respectively. The introduction of Si-PU compatibilizer is helpful for the dispersion of vulcanizated rubber particles and can decrease the size of the particles.5. The mechanical properties of TPSiV are affected by curing rate of silicone rubber. Compared with one-step addition of catalyst agent, the tensile strength, elongation at break and tear strength can be increased by 10.5%,8.9% and 5.7%, respectively, using sub-step addition method.6. TPSiV shows good re-processing properties. The decrease of the mechanical properties is not more than 15% after second-processing. TPSiV shows good heat-resistant behavior. The performance decreases near 10% after aging for 500h under 150℃.