Research Of Aramid Fiber Modification And Morphology On The Mechanical Properties Of Fiber Reinforced Natural Rubber Composites

Aramid fibers are widely applied in different fields and become the fastest growing,most productive and most useful high-tech fiber materials in the world based upon their excellent performances such as corrosion resistance,heat resistance,fatigue resistance,good dimensional stability,high strength and high modulus.The preparation of aramid fibers reinforced tread rubber composites is one of the important technical development routes of high-performance tires owing to the advantages of light weight of aramid fibers.As a desired reinforcing material of engineering tire,aramid fibers is attracting more and more attention and researches.In this paper,natural rubber was selected as raw material and aramid short fibers reinforced natural rubber composites as the research object,the aramid short fibers reinforced natural rubber composites were fabricated by a method of master batch.In order to improve the surface activity of aramid short fibers and enhance the dispersity and interface combination between natural rubber matrix,silane coupling agents were selected to modify the surface of aramid fibers.In addition,the aspect ratio of aramid short fibers and experimental conditions were further researched.The results are described as follow:(1)Different kind of silane coupling agents solutions(KH550,KH560 and KH570)with a mass concentration of 2.0% were adopted to modify the surface of aramid fiber at 65 ?,and then the modified aramid short fibers reinforced natural rubber composites were prepared and the mechanical properties were studied.The results showed that the aramid fiber surface activity and interface combination between natural rubber matrix were enhanced by modification with silane coupling agents.In addition,comparing the mechanical properties of aramid short fibers reinforced composities modified by different kinds of silane coupling agents,the test results indicated that the properties of composites modified by KH570 was the best and it was selected as the fiber modifier in this work.(2)The influence of fiber processing time,fiber dosage and coupling agent(3)dosage on mechanical properties of the composites were investigated.The test results showed that the best comprehensive properties of composites were obtained when aramid fiber was used the dosage of 2 phr,the mass concentration of silane coupling agents(KH570)was 1.0% and the fiber processing time were 10 hours,which was chosen as the experimental conditions for the further research.(4)The initial lengths of aramid fibers were chosen as the variables to carry out the effects of different aspect ratio of aramid short fibers on mechanical properties of the composites.From the experimental results,no apparent change was observed in the aspect ratio of aramid short fibers of the fiber/rubber composites modified by aramid fibers with different initial lengths.The value of fiber aspect ratio maintained in a certain range,indicating that the fiber aspect ratio was mainly depended on the processing technic.In addition,different aspect ratios of aramid short fibers resulted in different crack growth paths and destruction modes of the fiber/rubber composites.Lower or higher aspect ratios of the fiber were not conducive to improve mechanical properties of the composites.According to our research,the good comprehensive properties of the composites were obtained when the aspect ratio of aramid short fibers was about 220.