| Short fiber reinforced rubber composites (SFRC) has a series of good performance, such as high modulus, high puncture resistance, high tear strength, excellent dimensional stability, good creep and piercing resistance, are widely used in hose, V-tape and other products.Large amounts of waste short fibers (SWF) were produced, when recycling of waste tire recycled. In the recent years, enhance the value of SWF has been attracted more and more attentions. Undoubtedly, the SWF used to enhance SFRC is the best way. Ethylene-propylene-diene monomer rubber (EPDM) has excellent heat resistance and ozone resistance performance. And short fiber/EPDM composites are widely used to prepare heat-resistant rubber belt and other products. However, the poor of the dispersion and the interfacial adhesion between the SWF and the rubber phase need to be solved, when SWF applied to the SFRC.In this thesis, the morphology, structure and composition of the SWF were characterized firstly, than based on previous research; a new modified process was attempted. Cashew Nut Shell Oil (CNSL) and Carboxylatestyrene-butadiene rubber latex (XSBR) were chosen to pretreated SWF, the mechanism of CNSL and XSBR modified SWF has been explored. The effects of modified SWF on the reinforcement properties of EPDM contrast with DN66were investigated. Through the method of in-situ compatibilization, the effects of three kinds of compatibilizers, such as RC (melamine material with low shrinkage),60NSF(Light-colored mixture of aliphatic hydrocarbon resin) and TKM-80(alkylphenol with various structure, formaldehyde and proper modifier compounds) and their addition level on the interfacial adhesion between the SWF and the rubber phase and the mechanical properties of SFRC were investigated. Traditional test methods and some modern analytical techniques, i.e. infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), were used to monitor the effects of pretreated and compatibilizers on the structure characteristics and physical-mechanical properties of SWF/EDPM composites. The results were showed below: (1) The morphology, structure and component of SWF analysis shows that the main compositions of SWF are nylon6short-fibers and nylon66short fibers, the surface of SWF are rough, some of the SWF accompanied by a small amount of waste tire rubber powder. The length of SWF is mainly distributed in the3～4mm,30～34μm in diameter, and the aspect ratio for90to130.(2) When the short fiber addition level was less than20.0phr, the tensile strength of the SFRC declined, tensile elongation, hardness and tear strength increasing as the increase of the content of the short fibers. Compared with unmodified SWF, the mechanical properties of SFRC filled with SWF pretreated by CNSL were improved. The mixing processing and reinforcing properties of SWF were improved, when SWF was modified by CNSL. While SWF pretreated by6.0wt%CNSL had better reinforcing properties. When the concentration range of CNSL less than9.0wt%, the heat air aging resistance performance of the SFRC tended to increase as the concentration of CNSL increased.(3) Combination of CNSL and XSBR were chosen to pretreated SWF, while the concentration is3.0wt%, the conditions range of XSBR concentration within6.0wt%, the minimum torque (ML) and the maximum torque (MH) of the SFRC tended to declined as the concentration XSBR increased, and the scorch time (T10) and the optimum cure time (T90) of the SFRC had little effect. When the short fiber addition level was less than20.0phr, compared with unmodified SWF, the mechanical properties of SFRC filled with SWF pretreated by CNSL/XSBR were great improved.(4) When the addition level of compatibilizer was less than12.0phr, the Shore A hardness of the SFRC tended to reduced as the addition level of RC,60NSF and TKM-80. Also the modulus at100%elongation, the tensile strength and tear strength of the SFRC tended to first increase and then decrease as the addition level of compatibilizer. In the same short fiber addition level, compared with no added compatibilizer SFRC, the mechanical properties and the heat air aging resistance performance of the SFRC were increased after adding compatibilizer. Compared with RC and TKM-80,the mechanical properties and heat air aging properties of SFRC could be significantly improved by adding60NSF. (5) When the short fiber addition level was less than20.0phr, the Shore A hardness, the modulus at100%elongation and tear strength of the SFRC tended to increased, the tensile strength and the elongation at break of the SFRC tended to reduced as the addition level of unmodified SWF, DN66and SWF-33. In the same short fiber addition level, compared with unmodified SWF, the modulus, the tensile strength, the elongation at break and tear strength of SFRC filled with modified fiber SWF-33were improved to different degrees. In addition, the mechanical properties of SFRC filled with modified fiber SWF-33had good properties as filled with DN66.(6) SEM analysis results showed that the dispersion of unmodified SWF in the rubber matrix and the interfacial adhesion between the unmodified SWF and the rubber phase were poor. The dispersion SWF in the rubber matrix and the interfacial adhesion between the SWF and the rubber phase can be improved by the amount of CNSL or CNSL/XSBR modified SWF. Moreover, the interfacial adhesion between the SWF and the rubber phase was improved by the compatibilizers’addition. |
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