Mechanical Properties Of High Temperature Vulcanized Silicone Rubber Modified By Polyborosiloxanes

With their unique viscoelasticity,polyborosiloxanes have become a good material for shock absorption and protection.In order to explore the influence of the physical crosslinking network structure of polyborosiloxanes(PBDMSs)on the viscoelasticity of the system,hydroxyl terminated polydimethylsiloxane(PDMS-OH)with different hydroxyl contents(mass fraction)were reacted with boric acid to prepare PBDMSs with different boronization crosslinking density.The structure,thermodynamics and rheological properties of the as prepared samples were characterized.However,due to the viscous flow state of PBDMSs,it is not easy to directly produce and use.In order to solve this problem,this paper uses PBDMSs to blend and modify high-temperature vulcanized silicone rubber,and explores the mechanical properties of high-temperature vulcanized silicone rubber before and after modification.The results are as follows.With the increase of PDMS-OH hydroxyl content,the boronization crosslinking density of PBDMSs increased.When the hydroxyl content of PDMS-OH is 1%and 2%,crystallization of PBDMSs are observed.Moreover,PBDMSs possess the characteristics of excellent damping dissipation and excellent resilience.PBDMS5(the hydroxyl content of PDMS-OH is 9.2%)has the best damping dissipation ability and resilience ability.Its platform storage modulus value can reach 2221 KPa,and the maximum loss modulus value is 910 KPa.The hydroxyl content of PDMS-OH obviously affects the physical crosslinking network structure of PBDMSs,and thus has a significant impact on the dynamic modulus of PBDMSs.In practical application,the viscoelasticity of PBDMSs can be adjusted by changing the hydroxyl content of PDMS-OH according to the demand.The hardness,tensile strength and tear strength of PBDMSs modified high-temperature silicone rubber decreased,and the elongation at break increased significantly.The dynamic mechanical properties of the composite were improved,and when the blending content of PBDMS4(the hydroxyl content of PDMS-OH is 6%)is 45%,the damping dissipation and resilience of PBDMS4 modified high temperature silicone rubber are the best.High temperature silicone rubber has strain rate effect before and after modification,and PBDMSs modified high temperature silicone rubber has more remarkable strain rate effect.The hydroxyl content of PDMS-OH and the blending amount of PBDMSs affect the network structure of the composite,and then have a significant impact on the mechanical properties of the composite.In practical application,the mechanical properties of the composite can be adjusted by adjusting the hydroxyl content of PDMS-OH and the blending amount of PBDMSs.