| Today, Rubber plastics and fiber are the main three kinds of synthesizedmaterials used worldwide. Among them, rubber, because of its high elasticity andreactance together with good resistance to the air penetration and chemical erosion,is used as perfect polymer materials in all kinds of fields such as isolation tovibration, seal, insulation, resistance to abrasion and erosion, so much as adhesion.Nonetheless, the mechanical properties of rubber materials used alone are usuallytoo bad to meet the practical application need. In practice, vulcanizate is anorganic combination of much filler and rubber matrix by complex physical andchemical interaction. With multifarious new fillers appearing, a series of nano-sizematerials such as nano-diamond, multi-wall carbon nano-tube and some cheapfillers such as kaolinite, monotmorillonite, coal ash powder are incorporated intohigh-grade and low-grade vulcanizate. But carbon black is always the mostimportant reinforcement filler in rubber industry taking the high cost and badreinforcement effect of the new fillers into considerations. According to the staticreinforcement mechanism of the carbon black in rubber, the macro-molecularchains of the rubber cannot penetrate into the carbon black agglomerates. So, thesurface activity of carbon black plays an important role in carbon black reinforcingrubber. The chemical activity, but the physical activity of the carbon black surfaceis also important. The chemical activity of the carbon black surface mainly comesfrom the active hydrogen atom and the single electron freedom group at thesurface edge of micro-crystal and the function groups containing oxygen. It hasbeen proved by a long time investigation that in the polar saturated rubber, thefunction groups containing oxygen play an important role in the carbon blackreinforcement and in the non-polar unsaturated rubber, the active hydrogentogether with single electron freedom group do it. The adsorptions of the polarprobe and the alkene probe to the function groups containing oxygen at the carbonblack surface was compared by M.J. Wang and S. Wolff using IGC inverse gaschromatography. It was concluded that polar probe interacted more strongly withthe carbon black surface than did the double bond of alkene probes.Thus a new way can be tried to choose a compatilizer that can be affinity forboth the functional groups on carbon black surface and rubber so that thefunctional groups on carbon black surface will not be a handicap factor on theinteraction between carbon black/non-polar unsaturated rubber and the dispersionof carbon black. Based on this idea, the synthesized epoxy resin (TMBP) with fourside methyl groups, which contained polar epoxy groups of the high affinity forfunctional groups on carbon black surface and flexile methyl groups of highaffinity for rubber, was selected as the compatilizer in the furnace black fillednon-polar unsaturated rubber compounds. The bisphenol A epoxy resin E51 waschosen to compare the compatilization, which is of the similar molecular schemeto TMBP, but the two methyl-groups in E51 main chain handicapped by twoadjacent phenylenes was of little affinity chance for rubber matrix. So betterdispersion of carbon black in non-polar unsaturated rubber with TMBP than withE51 was expected. DOP was used to determine the function mode of the TMBP. Aseries tests such as the bound rubber contents, SEM, rheological properties, curingproperties of the mixure and the tension properties, tear properties, resistance tohot air aging, dynamic mechanical properties of the vulcanizate were carried out toexamine the idea.In the system of carbon black filled NR, bound rubber content decreasing withTMBP levels increasing agreed with the tension properties varying with TMBPlevels. When TMBP level was 2.5phr, the lowest bond rubber content representingthe best carbon black dispersion proved by the SEM photograph too and anexcellent tension properties accounting for the improved reinforcement effect wereobtained. It exhibited that TMBP acted as an interface compatilizer and thereexisted a critical TMBP level between carbon black surface and NR matrix. Theoptimum TMBP level (2.5phr) just coated the interface of the matrix and carbonblack aggregates. Further addition may lead to the overlap TMBP layer thatgradually deteriorated the properties. The critical levels of the E51 and DOP were10phr and 2.5phr respectively. When 2.5phr TMBP, 10phr E51 and 2.5phr DOPwere respectively incorporated into carbon black filled NR. The carbon blackdispersion and the curing properties of the mixture containing TMBP and thetension properties, resistance to hot air aging and dynamic mechanical propertieswere best. Compared with E51, a lower TMBP critical level and a bettercompatible effect showed the importance of the four side methyl-groups stretchingin space of TMBP in affinity for NR matrix. While the two methyl-groups in E51main chains handicapped by adjacent phenylenes were of little affinity chance forNR matrix. The effect of plasticizer DOP on properties was negligible.In the system of carbon black filled SBR, the tension properties increased withTMBP levels increasing. When TMBP level was 6phr, the tension properties wentto maximum. The optimum contents of E51 and DOP were 4phr and 6phrrespectively. When 6phr TMBP, 4phr E51 and 6phr DOP were respectively addedinto carbon black filled SBR, the carbon black dispersion of the mixturecontaining TMBP was best that has been proved by bound rubber content andSEM photograph. At the same time, the series properties of the vulcanizate with6phr TMBP were best. The TMBP critical level in this system was a little morethan E51. This come maybe from the high compatibition between TMBP and SBRmatrix that result in some ineffective TMBP cost. But the better compatibile effectof TMBP still showed the importance of four methyl-groups.The tear properties varying with TMBP in the two systems were not regularbecause of its complicated effect factor. In larger incorporation level, E51 wasbetter in improving the tear properties.In a word, as expected TMBP acting as a compatilizer between carbon blackand non-polar unsaturated rubber enhanced the dispersion degree of carbon blackin rubber matrix and then improved a series properties of the vulcanizate.
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