Interfacial Interaction Between Silica And Silicone Rubber And Its Relationship With Material Properties

Multicomponent multiphase polymers containing polymer composite materials, blended materials, reinforced materials and filled materials have two or more phases, therefore the properties of these materials depend largely on the interfacial interaction. Silicone rubber is a kind of special rubber which takes on outstanding capabilities, but which can achieve those capabilities only after reinforcement. As a result, interfacial interaction deserves to be studied in silicone rubber in particular.Firstly, HMDS modified silica (H-silica), A171 modified silica (A-silica) and KH-570 modified silica (K-silica) were prepared by different modifying agent. Both non-modified and modified silica were characterized and tested by Fourier Transform Infrared spectroscopy (FTIR), simultaneous TG apparatus and X-Ray Photoelectron Spectrometer (XPS). Modifying agents had been successfully grafted onto the surface of the powder. Thermal gravimetric analysis showed that the molar grafting rate per unit mass of modified silica was similar.Secondly, H-Silica filled silicone rubber composite material (H-Silica/MVQ), A-Silica filled silicone rubber composite material (A-Silica/MVQ) and K-Silica filled silicone rubber composite material (K-Silica/MVQ) were prepared. The interfacial interaction of silicone rubber was characterized with bound rubber, RPA, AFM and solid state NMR. Using the established methods, the impact of coupling type on interface was characterized. It was found that the silicone rubber with different interface had notable differences in bound rubber content, the adsorption layer of rubber molecules, the relaxation time, silica dispersion condition, dynamic mechanical properties, and cross-linking density.The stronger interfacial interaction between silica and rubber could lead to the more rubber content and thicker adsorbed layer of rubber,and the relaxation time of the system was smaller because of the more stable rubber molecules adsorbed to SiO2 surface.As a result, cross-linking density of the vulcanized rubber became greater.It was found that the sequence about interfacial interaction strength was that K-Silica/MVQ>A-Silica/MVQ> H-Silica/MVQ>Silica/ MVQ.Thirdly, in K-Silica/MVQ system, the effects of modified silica content on the interfacial interaction were studied. It was found that, when the content was low, the space between the larger aggregates could not form a complete particle network and interpenetrating network, which led to a low content of bound rubber, a thinner adsorbed rubber molecules layer, and a lower cross-linking density. With the increase of the content, the interfacial interaction was enhanced. When the content was 40 phr, the interfacial interaction was the strongest; while the filler content was too high, the interfacial interaction was gradually weakened due to the serious agglomeration of particles.Finally, the effects of interface properties on the mechanical properties of silicone rubber composites were studied. It was found that, the mechanical properties of material became better with the stronger interfacial interaction.