| Some scholars at home and abroad have done some work that calcined kaolin was filled in all kinds of rubber partially replacing the druss or silica, in order to reduce the production costs of the tire and loading level of the druss. The investigative literatures were less that sandy modified kaolin was filled in BR/SBR, and the composite material was used in tire industry. The purpose of the paper is that sandy kaolin, which was modifed in a new modified formula and technology, was filled with NR/SBR in the corresponding curing formulations and processes; the performance of the composite material prepared reach national standards of industrial tires.The paper systematically researched the modified conditions of the kaolin and pharmaceutical systems, and determined the corresponding sulfide formula and process. The modified and filled effect of kaolin was evaluated by the the activation index and mechanical properties of filled rubber. The pH and Zeta potential of the kaolin and silica was researched by Nano/submicron size analysis and potential. The vibrative characteristics of the function of modified kaolin and the composite material was researched by FT-IR. The dispersion and interfacial characteristics of the kaolin in the rubber was studied by SEM. The thermal stability of the composite material was studied by the thermal analysis. Specific conclusions are as follows:l.The suitable conditions of kaolin modification, which was the primary modifier A11.5%, the activator B22%, the vice modifier E12%, the modified temperature90℃and modification time30'was determined by the conditioning test of the four primary modifier of A1-A4, the three activator of B1-B3and the two vice modifier of E1-E2.2. The final vulcanization recipe, which was the stearic1.0phr, the zinc oxide5.0phr, A1.8phr, B2.0phr, the softener6.0phr, the antioxidant1.0phr was determined by the orthogonal, optimizing and dosage test of the vulcanization formula. 3.It is determined by the single-factor test of the curing process that the curing conditions was the curing temperature150℃, the curing time8, the loading of modified kaolin60phr and ratio of NR/SBR40:60.4. The composite material which was preparated by NR/SBR filled by two modified kaolin from Maoming, met the GB of the industrial tire, the agricultural tire, the solid tire and car inner tire. The tensile strength of the composite material which was preparated by NR/SBR filled by the modified kaolin from Beihai, met the inner tires GB of the industrial tire, agricultural tire and car tire. Its elongation at break met the GB of the industrial tire, the agricultural tire, the solid tire and car inner tire. Its hardness met the GB of he industrial tire, the agricultural tire and car inner tire. Its wear volumes didn't meet the GB of the industrial tire, the agricultural tire, the solid tire and car inner tire.5.The analysis of the pulp pH and Zeta potential test of the kaolin and silica derived that the pulp pH of the unmodified and modified kaolin was less than5.20, and the pulp Zeta potential absolute value of the kaolin basically was less than42.00mv. The pulp pH of the unmodified silica hydrated was6.55, and the pulp pH of the modified silica hydrated which was5.90dropped. The pulp Zeta potential absolute value of the unmodified silica hydrated was45.50, and the pulp Zeta potential absolute value of the modified silica hydrated which was63.25mv rose.6.The IR of the modified kaolin had the absorption peak of the C-H. This showed that coupling agent and kaolin could be physical adsorption or chemical bonding. The absorption peak of872cm"1in the IR of the composite material without filler was similar to that in the IR of the accelerant. This shows that the rubber and accelerant could be physical adsorption or chemical bonding. Comparing the IR of modified kaolin/NR/SBR with the IR of unmodified kaolin/NR/SBR, The absorption peak of1538cm-1and1450cm-1strengthened, and the absorption peak of1028cm-11005cm-1and910cm-1weakened and happened displacement. These changes could be caused by the new functional characteristic peaks.7.The SEM of the composite material without filler tensile cross-section showed that kaolin particle was coarse. The SEM of unmodified kaolin/NR/SBR composite tensile cross-section showed that unmodified kaolinite dispersed poorly in the composite material, and combined poorly with the rubber. The SEM of modified kaolin/NR/SBR composite tensile cross-section showed that most modified kaolinite evenly distributed in the rubber.8. The thermal analysis of the composite material without filler, unmodified kaolin/NR/SBR and modified kaolin/NR/SBR showed that comparing the composite material with the filler with the composite material without the filler, the initial weight loss temperature enhanced20℃, its maximum weight loss29%, its end decomposition temperature loss10℃and the exothermic peak which was caused by the rubber cross-linking reaction enhanced119℃. The phenomenon above showed that the kaolin enhanced the thermal stability of the composite. |
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