| In this paper,silica was used instead of carbon black to reinforce natural rubber,and modified white carbon with coupling agent was used to improve the properties of rubber.Natural fibers were used instead of synthetic fibers,and the surface of the fibers was treated to improve their compatibility with the rubber.At the same time,compatibilizer was added to enhance the interfacial adhesion between fibers and rubber.Based on the study of the physical properties and rheological properties of the composites,the effects of different modifiers and compatibilizer on the properties of rubber materials were investigated.The details are as follows:(1)This paper adopts the method of wet modification,silica surface was grafted with proper coupling,and the effect of modified silica on properties of rubber composites was studied.It was found that the mechanical properties of the composites were improved obviously after modification of silica,and the modification effect of coupling agent NXT was the most obvious.The infrared spectrum and profile shows that,after the surface treatment,the hydroxyl number of the surface of silica modified was decreased,the silica was dispersed more evenly in the rubber matrix,the aggregation phenomenon was weakened,and the compatibility of silica and rubber was improved obviously.From the analysis of rheological property,found the network degree of filler was decreased after adding coupling agent,and the formation of packing network was blocked,the Payne effect of the mixed rubber was reduced,so that the G’ and G’’ of the rubber material was decreased.At the same time,it was found that the tanδ decreased significantly when NR was filled with silica and compared with NR filled with carbon black,the results showed that the rolling resistance of silica filled rubber composites was decreased.In capillary rheological test,the shear viscosity of mixed rubber shows obvious shear thinning with the increase of shear rate,it reflects that the rubber is a non Newtonian fluid,and the addition of coupling agent results in a decrease in elongational viscosity.Considering the effect of different coupling agent is KH560 < Si69 <NXT,coupling agent NXT is the best.(2)The best coupling agent NXT was used to treat silica,and the effect of different silica content on the properties of natural rubber composite was studied.The results shows that the strength and elongation at break increase first and then decrease with the increase of modified silica content,the tensile stress and adhesive content increased continuously,and the overall performance was the best at 50 phr.Rheological performance shows that within the strain range,the G’、G’’、η* of the mixed rubber increased with the increase of the content.The Payne effect was more and more obvious,which reflects the reinforcing effect of SiO2 particles.In the temperature scanning of vulcanizate,with the increase of filler content,G’ and G’’increased due to the increase of packing network,but with the increase of temperature,tanδ was decreased.From the morphology of the section,it was found that the roughness and dent of the fracture surface were deepened with the increase of the number of fillers,and the dispersion degree of silica was improved,and the 50 phr isthe best.(3)The wood fiber was treated with proper coupling agent(KH550、KH570、NXT)by the method of wet modification,the effect of different modified wood fibers on the properties of rubber composites was studied.The results showed that tensile stress and tear strength were improved after treated with coupling agent,among them,the coupling agent KH550 was the best.When the fiber was treated with coupling agent KH550,which can effectively improve the cutting resistance,the-OH content of the fiber surface was obviously reduced,and Si-O characteristic peaks appeared at1161cm-1.Moreover,the treatment of coupling agent reduced the formation of the fiber network,and the viscosity of the compound was reduced.Which can improve the modulus of composite material,and improve the ability of the tire to resist stress and deformation in the process of using.After the fiber was treated with silane coupling agent KH550,the damage of the cross section was serious,and the interfacial adhesion between fiber and rubber was improved obviously,the RISE value was also corroborated.DMA analysis showed that the modification of fiber improved the compatibility of fiber and rubber,and the silane coupling agent KH550 had better effect on improving the fiber surface,the tanδ value of the composite at about 60℃was also relatively small,so the composite has lower rolling resistance.(4)KH550 modified wood fiber was selected and different compatibilizer was added to improve the combination of fiber and rubber.The effects of different compatibilizer on mechanical and compatibilization of fiber reinforced rubber were studied.The research shows that the addition of compatibilizer increases the tensile stress of the material obviously,and the effect of the imported compatibilizer was the most obvious.The addition of compatibilizer reduces the quality loss of the cutting sample,and the material added with imported compatibilizer has the best cutting resistance.The import compatibilizer as a bridge between fiber and rubber,enhanced the bonding of the interface,so that the network structure is not easily damaged,so as to improve the modulus and viscosity of the mixed rubber.Moreover,the addition of the imported compatibilizer made the fiber extracted or pulled off to be rough and adhered to the rubber,indicating that the imported compatibilizer could effectively improve the interfacial adhesion between the fiber and the rubber.The increase of RISE value also reflects the addition of compatibilizer to improve the interfacial adhesion between fiber and rubber.DMA research showed that the addition of imported compatibilizer can not only improve the interfacial adhesion between fibers and rubber,but also reduce the rolling resistance of composite materials in use and save energy consumption.(5)On the basis of the foregoing,the import compatibilizer was selected,and the effect of the content of modified fiber on the properties of composites was studied.The results showed that the tensile stress of the composites are obviously increased with the addition of the fiber,when the fiber content is 6phr,the composite has better comprehensive properties.The existence of wood fiber is beneficial to the improvement of cutting resistance.But when the fiber content is too high,which will reduce the cutting resistance of the composites.And with the increase of fiber content,the fiber rubber network structure was increased,modulus and viscosity ofrubber was increased.With the increase of fiber content,the dispersion of fibers decreased and the aggregation increased.Combined with mechanical properties,rheological properties and DMA properties,it was found that fiber content was more suitable for 6phr. |
