Study On The Binding Mechanism Of Addition-cured Silicone Rubbers/nylon Interface

Addition-cured liquid silicone rubber is a new type of silicone with excellent performance and has been widely used in many fields.However,due to the less polar groups connected to Si-O chains of the silicone rubber system,the entire polysiloxane molecule exhibits non-polar and low cohesive energy.Therefore the adhesive ability between the silicone rubber and the inorganic material or the polar organic material is usually poor.In this paper,a primer which comprised y-glycidoxypropyltrimethoxysilane(GPTMS),tetrabutyl titanate(TBT),ethyl silicate(TEOS)and ethyl acetate was prepared to improve the adhesion of addition-cured liquid silicone rubbers/nylon interface.The binding mechanism was studied on the base of the experimental data and microstructure observation by SEM.The results show that uniform organic-inorganic hybrid films from the primer form on the silicone rubber/nylon interface.The Si-OH bands and epoxy groups in hybrid films reacted with Si-OH bands in the silicone rubber and amino groups in nylon respectively,as the results of forming a good chemical bonding on the interface.In this process,the elevated treatment temperature promotes the completion of the chemical bonding.At the same time,on the assisted physical chimeric action between nylon and the hybrid film,the chemical bonds between them form deeply into the region below the surface layer of nylon,which produces a better adhesion.In order to improve the adhesive properties of nylon on the surface of cured silicone rubber,hydrosilylation reaction occured between the hydrosilicone oil and the monomer,acrylic glycidyl ether(AGE),to generate the modified silicone rubber containing epoxy groups in the role of the platinum catalyst.The results show that the solution,in which PA and formic acid has a mass ratio of 1:3,forms an uneven film on the surface of modified silicone rubber and better adhesive properties between them can be achieved.By SEM,more wrinkles can be observed on the surface of the modifed silicone rubber,which increase the surface area of the substrate.Between the-NH2 in the PA with the epoxy group in the modified silicone rubber formed more strong chemical bonds form,which are promoted with the elevated temperatures.After the silicone rubber is modified,the presence of the polar epoxy group increases the surface energy.As a result,PA solution is easy to wet on the surface of the silicone rubber and thereby the bonding force between them is increased.