| Paraaramid pulp(PPTApulp, PAP) is a kind of short fiber with outstanding physical and chemical properties. PAP is usually manufactured by paraaramid fiber(PPTA fiber, PAF) through fibrillation. It can be used in rubber as the modulus modified materials and has broad application fields, such as:in conveyor belt, transmission belt, tire etc.. PAP is composed of a main fiber and lots of miero-nano fibers, micro-nano fibers attached to the main fiber. The specific surface area of PAP is big. PAP has a certain length and diameter distribution. The special structure of PAP could lead to the mutual entanglement of micro-nano fibers and the electrostatic adsorption phenomenon is serious, so PAP is difficult to disperse uniformly in the rubber; In addition, the steric effect of benzene ring, the strong intermolecular hydrogen bond interaction and the high degree crystallinity result in a low surface chemical activity of PAP. Therefore, pre-dispersion and interfacial modification of PAP play an important role in reinforcement of rubber. In this paper, firstly, the preparation process of pre-dispersion aramid pulp masterbatch(PAPM) by rapid mixing was explored, and the application to the conveyor belt of PAPM were discussed. Secondly, PAP-rubber composite material was prepared by the method of the emulsion coagulation,then the mechanism of PAP reinforcing rubber was discussed.Firstly, we analysed the difference between physical appearance and chemical elements of PAP and PAF. According to the special physical structure of PAP, we optimized the traditional PAPM formulation (PAP, polymer carrier, isolation system, dispersion system, lubricating system, etc.), abandoned the solid particles as isolation system; For further exploring, we reselected the different components:polymer carrier, lubrication system, dispersion system and the new formula PAPM was prepared. The dispersion state of PAP and processability of PAPM were investigated. According to the polymer composites modulus matching principle, we applied PAPM to the high temperature resistant conveyor belt adhesive layer and explored the rule of peeling strength between adhesive layer rubber and canvas material before and after aging; we also applied PAPM to ablation resistant conveyer belt cover layer and discussed the impact of PAP on the cover layer of ablation resistant properties.Secondly, we successfully prepared good dispersion and interface adhesiveness PAP-rubber composite materials by the emulsion coagulation The mechanism of PAP reinforced rubber was investigated. PAP has good water absorption, it can be suspended in water. In the experiment, nano-clay was used as the isolation agent, the VPL and silane coupling agent(KH550/Si69) were used as interfacial modifier. We investigated the dispersion of PAP in the rubber matrix. Short fiber interface slip factor(SFISF)was used to discuss the interface adhesive strength between rubber and PAP.Sb2O3 is a white powder and widely used in flame retardant materials. It is a kind of inorganic flame retardants and can significantly improve the flame retardant properties of materials especially used with halogen flame retardant compound. But Sb2O3 powder particles are easy to agglomerate when they are applied to rubber, and the interfacial effect between particles and rubber is weak. This will lead to a decline in the efficiency of flame retardant and the mechanical properties of composite materials. In order to solve the above problems, the interface modification of Sb2O3 and the pre-dispersion Sb2O3 masterbatch (PSM)was successfully prepared.We modified Sb2O3 powders with silane coupling agent(Si69). To determine the optimal modification conditions (the content of Si69, modification time and temperature etc.), the activation index, contact angle measurement,TGA and EDS were used, we explored the preparation technology of PSM, and analysed the dispersion and the strength filler network structure of Sb2O3 particles. We applied PSM to rubber and discussed the mechanical properties and flame retardant properties of composites. |
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