Preperration And Research Of Nano-hybird Materials About Surface Modification Of Silica/Rubber

As an excellent reinforcing material, nanosilica?commonly known as white carbon black? has gained extensive applications in the field of rubber materials. For example, inexpensive silica with excellent performance can be used as an alternate of carbon black to reinforce green tire tread rubber?SSBR/BR?. It can also be used to improve the mechanical properties of silicon rubber composite insulator and silicone sealant. This thesis selects a series of dispersible silica?DNS? and reactive silica?RNS? to reinforce high-performance tread of green tire, methyl vinyl silicon rubber and silicone sealant, and it investigates the reinforcing efficiencies of various reinforcing agents. The main research contents and conclusions are as follows:1. The optimum content of highly dispersible silica in SSBR/BR was established, and the influences of various types of silica on the mechanical properties of SSBR/BR were discussed, and. Results show that the optimum content of 1165 MP in SSBR/BR is 50 phr. DNS-1 and DNS-3 have the best reinforcing efficiency to mechanical properties of SSBR/BR, and their reinforcing efficiency is similar to that of 1165 MP. Besides, DNS-1/SSBR/BR hybrid material exhibits better wear resistance and wet sliding resistance as well as a smaller rolling resistance than 1165MP/SSBR/BR hybrid materials. In one word, silica with a large specific surface area, pore size and pore volume exhibit good reinforcement to physical and mechanical properties of SSBR/BR, which is because the nanosilicas have a large contact area and strong interactions with the rubber molecules.2. The influences of ratio of raw materials and DNS structure characteristics on the mechanical properties of silicon rubber insulator were investigated, and comparatives studies with highly dispersed commercial silica T-928 as a standard. Results show that the optimal formula of the silicon rubber insulator made of silicon rubber, Si O₂,ATH, hydroxyl silicone oil, A-151 coupling agent, and vulcanizing agent is 100:36:100:2.0:0.1:1.5?mass in gram; ATH refers to Al?OH?₃?. By exploring the different coupling agent on the mechanical properties of silicone rubber insulator, results show that the coupling agent A-151 with double bonds exhibits the best reinforcing function, which is because its double bonds can undergo addition reactions with the vinyl of the silicon rubber, thereby increasing the cross-linking density and improving the mechanical properties of the SiO₂/ATH/SR composite. As the DNS series of nanosilicas have a specific surface area of 300 m2/g?determined by BET method?, a pore size of 25 nm and a pore volume of 2.0 cm3/g as well as a surface hydroxyl content of 5×1017/m2, they have the best reinforcing function for the silicon rubber. In the different kind of silica, DNS-3 exhibits the best reinforcing efficiency for the silicon rubber, which could be closely related to its relatively large specific surface area?341 m2/g? and small size?5 nm?. When ATH modified by stearic acid?mass ratio: 1:1000?, i.e., m-ATH, was used as a filler of SR, the mechanical properties of SR can be greatly improved. This could be because the carboxyl of the stearic acid is chemically bonded with the hydroxyl of ATH via an esterification-like reaction, and the inter-twined long carbon chains of stearic acid contribute to enhancing the interfacial compatibility between ATH powder and the methyl vinyl of the silicon rubber. The SiO₂/ m-ATH/SR hybrid material with DNS-3 as the reinforcing agent and m-ATH?stearic acid dosage: 0.1 g? as the flame-retardant exhibits desired mechanical properties as well as flame-retarding performance and electrical properties and is qualified as the shed of high-speed rail insulator.3. The effects of silica moisture content on the workability of silicone sealant were analyzed. The differences in the reinforcing efficiencies of various nanosilicas for the silicone sealant were discussed, and the causes leading the differences were explored. Results indicate that, when the moisture content of the nanosilicas is below 1%, the as-obtained silicone sealant exhibits a high extrusion rate, a long surface curing time and a high degree of drooping, and it has desired workability as well. DNS-1 and nanosilica HL-200 prepared by gas-phase method exhibit good reinforcing efficiencies, relevant reinforced saline sealants has a tensile strength of 1.25 MPa and an elongation at break of about 350%. Moreover, the silicone sealant reinforced by DNS-1 with a lower apparent density has a higher tearing strength than the same silicone sealant reinforced by HL-200.