Rheological And Mechanical Behaviors Of Short Fiber And Silica Filled Natural Rubber Compounds

Short fiber has a unique reinforcing effect to rubber materials combining high elasticity and strength. Improving the dispersion of short fiber in rubber matrix and the interaction between fiber and matrix by appropriate methods are key factors influencing the reinforcing effect. On the other hand, silica, commonly used as a filler with marked reinforcing effect, can form particle network in the rubber matrix, which strongly influences rheological and mechanical behaviors of filled rubbers.In this dissertation, nylon short fiber (NSF) and silica were used to fill natural rubber (NR) to prepare composites compatibilized by maleated natural rubber (MNR). Influences of NSF content on dynamic rheological behavior were discussed for the un-compatibilized and the MNR compatibilized compounds. Besides, mechanical properties of the vulcanites were analyzed. It was indicated that NSF can improve stress at definite elongation, tear strength and dynamic modulus and MNR could efficiently enhance the compatibility between NSF and rubber matrix to improve the fiber dispersion.The compatibilized NSF/NR masterbatch was added into NR filled with silica, and dynamic rheological behavior of the compounds was investigated with respect to NSF or silica content. The modified two phase model was used to analyze the enhancement effect of "filler phase" constructed by introducing NSF, silica or the NSF-silica dual phase filler. It is found that the dual phase filler greatly improves both the elastic and the viscos contributions of the "filler phase" with a markedly reduced relaxation dynamics. Furthermore, the reinforcing factor and strain amplification factor of the compounds with dual phase filler were higher than those of the compounds with single phase filler.Mechanical and dynamic mechanical properties and morphologies of the vulcanites were studied for clarifying influence of the material composition. Results show that both NSF and SiO2 can improve the initial modulus, tear strength, and hardness. Furthermore, adding NSF could reduce peak value of loss factor, which benefits for preparing rubber materials with high wet resistance and low rolling resistance.