| The paper related to study of using ultra-fine full-vulcanized powdered carboxylated nitrile rubber(UFPCNBR), ultra-fine full-vulcanized powdered styrene-butadiene rubber(DB-50, DB-70) and ultra-fine full-vulcanized powdered nitrile rubber(UFPNBR) to prepare the UFPR/NR/SBR tread rubber composites. Especially studying the effect of UFPR particles on dynamic properties and surface properties of modified tread rubber at the time of studying vulcanization characteristics and mechanical performance. We prepared the good anti-slide stability and low rolling resistance tread rubber by optimal choice of UFPR particles, bringing out the basic experience theory system of skid-resistance to better its theory system mechanism, and provided a new research idea for preparation of tread compound material that could be safe to drive under the condition of high temperature and high-speed.The research on mechanical properties showed that not only the tensile strength and tear strength of tread rubber modified by nonpolar DB-50, DB-70 could reach 20MPa and 50N/mm respectively but also the elongation at break was improved which could be able to basically meet the demands of the mechanical property of tread rubber. The tread rubber modified by polar UFPCNBR, UFPNBR also improved the elongation at break while having a degree of decrease on tensile strength and tear strength.The thermodynamic properties showed that the tanδ of modified tread rubber composites by UFPNBR, DB-50, DB-70 with temperatures -10℃ to 10℃ was significant improved, that is, to increase the wet-skid resistance of tread rubber, which could be increased by 31.71%,56.64% and 21.43%. UFPCNBR particles could be not effective to enhance the wet-skid resistance of tread rubber composites. On the basis of these, the paper layed emphasis on the research of the surface properties of modified tread rubber composites by UFPR, which showed that the surface properties of modified tread rubber could be improved effectively by UFPR. The particle DB-50 decreased the surface water contact angle and enhanced the macro modulus and micro modulus of the tread rubber composites obviously, which had rougher surface after friction. All these contributed to decreasing water film sickness and having the capability for great destruction on the water film, which were benefit to the wet-skid resistance of tread rubber. On the basis of the wet-skid resistance which was researched by predecessors, by considering the factors of affecting the water film thickness and supplementing the existing single method to evaluate the wet-skid resistance, which only used the tan8, therefore, putting forward the simple empirical formula of the wet-skid resistance:The experimenta results of rubber processibility analyzer(RPA)showed that the tanδ of the tread rubber modified by 25phr UFPCNBR tested under 10% strain and temperatures 30℃ growed by 13.98 percent, which could increase the dry-skid resistance of tread rubber, while increasing the rolling resistance; The tanδ(30℃) of the tread rubber modified by 25phr DB-50 was boosted with about 4.66 percent, while the tanδ(60℃) decreased about 16.18%, which not only strengthened the dry-skid resistance but also lowered the rolling resistance. The dry-skid resistance and rolling resistance of the modified tread rubber by UFPNBR and DB-70 couldn’t be improved ideally. The research on the surface energy of modified tread rubber by UFPR showed that the surface energy of tread rubber composites could be increased by UFPR. The surface energy of tread rubber modified by DB-50 was 5 times beyond that of NR/SBR compounds, enhancing the forces between tread rubber and pavement, further contributing to enhancing the dry-skid resistance. On the basis of the skid-resistance and theory of friction which was researched by predecessors, the paper pointed out the rationality of using tanδ and surface properties to evaluate the skid-resistance. According to the experimental results and the formula of the rubber coefficient raised by Moore, a simple formula for the dry-skid resistance could be presented:... |
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