Study On The Preparation, Structure, And Properties Of High Performance Rubber Based Nanocomposites

Rubber nano-composite is a kind of novel composite which is made of rubber as matrix(continuous phase) and particles as dispersed phases with at least one dimension size less than 100nm. In this paper, three kinds of rubber nano-composites have been studied:Styrene butadiene rubber(SBR)/silica nano-composite, hydrogenated butadiene acrylonitrile rubber(HNBR)/silica nano-composite and styrene butadiene rubber(SBR)/huaguang carbon black(HG-CB) nano-composite. The preparation, structure and properties of the them have been discussed.In the first part, SBR/silica nano-composite prepared by wet compounding method has been studied in detail. In previous research, we found that the biggest problem of wet compounding method for SBR and silica is the loading weight of silica lost too much during the process of silica co-flocculated with SBR. In this paper, two kinds of methods have been used to resolve this problem.The first method included several steps as follows:first, silica particles surface were organically modified by dry method; second, the organic silica slurry was prepared by putting the modified silica into water and mixed by mechanical agitation; the third step, SBR latex was blended with the organic silica aqueous suspension, and then emulsion was broke by adding into flocculating agent suspension; at last, the SBR/silica nano-composite was achieved by this intermittent wet compounding method via drying, mixing with other agent using traditional mixers and vulcanizing. The influence of blending times of coupling agent and silica, amount of coupling agent and slurry concentration on properties of composite was studied. The results show that, the optimum blending times of coupling agent and silica is 15 times; the greatest concentration of organic silica slurry is 15 percent; with the increasing of coupling agent amount and the surface modification time, the degree of the surface organic modification of silica, the grafting rate of coupling agent and mechanical properties of the composites all increase. Comparing this intermittent wet compounding method with traditional dry mixing method, the efficiency of coupling agent, stress at definite elongation by wet method is lower, scorch time of composite prolong, and tear strength becomes better.The second method was that silica surface was organically modified in slurry. Firstly, the silica slurry was prepared by putting the hydrophilic silica particles into water and blending with intensity mechanical agitation. Then,the silane was added into the aqueous suspension to in-situ modify the silica nano-particles, and after that, mixed the suspension with SBR latex before adding flocculants to co-coagulate silica and rubber. The obtained SBR/silica nanocompounds were dried, further mixed using traditional mixers and vulcanized at last to give the nanocomposites by this continuous wet compounding method. In this part, effect of different preparing methods for silica slurry, reaction time of coupling agent and silica slurry and different amount of silica on the properties of composites was studied. The results illustrat that with the increase of concentration of slurry or extended the stirring time could decrease the particle size of silica in water, and delay the subsidence of silica. The optimal solid content of slurry is 15 percent. With the increase of reaction time of coupling agent and silica, the particle size of organic surface modified silica in water becomes larger, and the weight loss of silica co-coagulate with rubber latex decreases. Compared to the composites prepared by dry mixing method, the ones achieved by wet compounding method have better filler dispersion, higher tensile strength, lower tear strength, mooney viscosity, permanent deformation, dynamic compression set and dynamic temperature rise. And they have similar hardness, Stress at definite elongation and abrasion performance. What's more, by using this continuous wet compounding method, SBR/silica nano-composite loaded high concentration of filler(100phr) with great filler dispersion and good mechanical properties could be prepared.In the second part, the effect of technological parameters of in-situ modified dispersion method, such as the amount of coupling agent, heat treated time, heat treated temperature on the structure and properties of HNBR/silica nanocomposites were studied. Payne effect was used to characterized the structure of filler network in composites. The results showed that the micro-dispersion of filler became better while increased the amount of coupling agent or rised the treated temperature or extended the treated time. Some abnormal phenomenons appeared in this system which was different from that of non-polared rubber loaded silica system. The dispersion of filler in uncured HNBR/silica compound became worse when coupling agent KH570 was introduced at room temperature, but after heat treated or store at room temperature for a long time, the dispersion of the filler in the composite became better. This abnormal phenomenon is related with the competition relationship of intereaction among coupling agent KH570, hydroxyl groups in the surface of silica and cyano group of HNBR.In the third part, a novel carbon black with special hollow structure and high structure degree named Huaguang carbon black and the properties of SBR/huaguang carbon black nano-composite were studied. Mechanical test, dynamic mechanical test and functional properties tests have been used to characterized this new kind of composite. The results showed that with the increase of amount of huaguang carbon black, strong filler network structure was formed in SBR matrix, the mooney viscosity of SBR/HG-CB compound, storage modulus in small strain amplitude increased dramatically, and the mechanical properties of SBR/HG-CB nano-composite increased which showed great reinforce effect in low filler concentration. Content of bound rubber could be measured when the filler content was 25phr and the content of bound rubber increased while the concentration of filler increased. With the increase of filler content, the volume of wear and volume resistivity decreased and coefficient of thermal conductivity increased linearly. Comparison with common carbon black N330, the SBR/HG-CB nano-composite has higher tensile strength, greater thermal conductivity property and better electrical conductivity property.