Study On Pretreating Technique Of Aramid Pulp And On Structure,Property And Application Of Aramid Pulp Reinforced Rubber Composites

Aramid pulp(AP) has very unique ultrafine short fibre structure: the surface of AP backbone fiber (diameter is about10microns) encloses a large amount of ultrafine fibrils (diameter is0.1-2microns), which are associated with backbone fibres loosely. AP is a kind of ideal asbestos-substituting fibers for sealant, strengthening material and friction material, competing with glass fibre and carbon fiber mainly.The pretreatment technology of " separating by lubricating and penetrating" AP fibres has been invented in this paper, and by utilizing this technology, AP fibers with very high specific surface area can be uniformly dispersed into rubber matrix and also kept well-stretched posture (openness), consequently the potential reinforcing capacity of high performance AP fibres would be fully explored.With the aid of SEM or ESEM, the fibre surface microstructures of no-pretreated AP and modified AP predispersed composition are investigated, and by comparision study on microstructure and mechanical property of AP fibre reinforced rubber composites, the validity of pretreating method of " separating by lubricating and penetrating" has been proved in this paper.The reinforcing mechanism of AP short fibres in rubber(CR,EPDM,or HNBR) matrix has been discussed in this paper, and it has been shown that the reinforcing effects of AP depend mainly on the dispersing uniformity and openness of those ultra-fine short fibres of AP in rubber matrix.The correlation between microstructure and macroproperty of AP fibre reinforced rubber composite has been investigated and it is shown that the interfacial adhesion between AP ultrafine fibre and CR,EPDM,HNBR,or NR/BR matrix is very strong, AP fibers have high modulus built-up efficiency. An important characteristic of reinforcement with AP fibres is the ability to built composite modulus with little effect on the hysteretic properties of the composite, i.e."modulus-hysteresis balance". Anothoer important characteristic of reinforcement with AP fibres is the ability to built composite modulus without significant increase in compound viscosity, i.e."modulus-viscosity balance".The reinforcing properties in CR matrix of seven different specification of AP fibres, which are manufactured by DuPont,Teijing Twaron, and Shanghai Yiji scientific&technical corporation, have been researched in this paper, and it is shown that the larger the surface area of AP fibre is, the better strengthening performance of AP fibre is. The dispersibilty, extension and orientation of different variety of AP fibres are not the same, therefore the enhancement function on the rubber is not the same.Through the research of the high-temperature mechanics performance of AP reinforced rubber composite, we find that AP superfine fibers not only have a very high modulus-bulit up effeciency under the high temperature, but also can improve the high-temperature strenghth of the composite. so AP fibres are very suitable for reinforcemen of heat-resisting EPDM transmission belt.