Preparation And Application Of Epoxy Polysiloxane

Polysiloxanes are usually copolymerized to prepare block copolymers with various properties to expand their applications.Addition type liquid silicone rubber is non-polar,and the bonding behavior between various materials and it is poor.The development of addition type liquid silicone rubber with high adhesion has important application value.The flexibility of polysiloxane can make up for the hard and brittle shortcomings of epoxy resin,and silicone can be used to toughen epoxy resin.Through the hydrosilylation reaction,the modified polysiloxane(E-PDMS)is obtained by using hydrogen-containing silicone oil(H-PDMS)and allyl glycidyl ether(AGE),which contains side chain epoxy groups and part Active hydrogen.The effects of different reaction conditions on modified silicone oil were studied.The optimal conditions for the reaction are: the addition of cassette catalyst is 12 ppm,the molar ratio of reactants(C=C:Si-H)is 1:1.2,and the reaction temperature(Tr)Is 80 °C,and the reaction time(tr)is 7 h.E-PDMS was added to the addition molding silicone rubber system for curing,to study the improvement of epoxy group's adhesion to silicone rubber,and to explore the influence of different epoxy values on other related properties.As the epoxy value increases,the final residual content increases by 10%,and the initial decomposition temperature decreases from 447.05 °C to 358.88 °C.Experiments show that modified silicone rubber has better resistance to non-polar solvents(toluene),but relatively poor resistance to extreme solvents(acetone).The UV transmittance first increases and then decreases with the epoxy value.The transmittance at 351 nm drops from 92.41% to91.59%.With the increase of epoxy group content,the cross-hatch drop-off rating increased from 4 to 0,the shear tensile strength increased from 0.18 MPa to 8.08 MPa,the contact angle decreased from 114.24° to 93.24°,and the surface energy increased from 23.995 to 31.527.m N/m,the adhesiveness of modified silicone rubber has been improved.The analysis of the curing process shows that as the content of E-PDMS increases,the initial curing time of the reaction system is constant toward the low temperature direction and the time required for curing to be completed shortens.With the increase of E-PDMS content,the thermal decomposition temperature of epoxy resin increased from369.11 °C to 400.65 °C,the residual carbon content increased from 22.71% to 31.01%;the tensile properties decreased from 2.450 MPa to 0.692 MPa,and the elongation at break The rate increased from 144.328% to 274.310%,and the shear tensile strength decreased from 1.5075 MPa to 0.782 MPa with the increase of E-PDMS.Surface performance analysis showed that the addition of E-PDMS increased the contact angle of epoxy resin from 85.75° to 107.48°,and the surface energy also decreased from34.398 to 26.339 m N/m.The analysis of the cross-section morphology showed that when the polysiloxane was added at 10 wt%,the polysiloxane was uniformly dispersed in the epoxy resin,which significantly improved the toughness of the epoxy resin.Finding a suitable curing agent and curing method to make the hydrosilylation reaction and epoxy curing proceed at the same time may be a new direction for addition molding silicone rubber/epoxy resin modification in the future.