Research On The Properties Of Aramid Fiber Reinforced Natural Rubber Composite

The properties of aramid fiber(AF)reinforced natural rubber(NR)composite has been studied in the thesis,for obtaining high-performance engineering tire tread compound,through 3 aspects which are surface modification of AF,adjustment of processing and optimization of compatilizer.The relationship between the dispersion of fillers or the interfacial state and the properties of mechanical has been investigated,focusing on the analysis of interfacial state and interfacial bond strength,through characterization of rheology performance and interfacial bond state.Additionally,another emphasis has been put on the abrasion of obtained AF/NR composite,which was independently acted through the composite structure and abrasive phenomenon.(1)The effect of thermal oxidation treatment time on interfacial affinity,on fibers state and on mechanical properties of the reinforced natural rubber was discussed.Its result shows the retained fiber length is so lower than the critical fiber length that fibers would be pull out rather than broken at the time of composite fracture.Moreover,the interfacial bond strength increased firstly and then decreased with the increase of treatment time,and it reached its top at 20 min.The trend was in agreement with mechanical strength properties of composite.The process of masterbatch on torque rheometer was taken as example to explore the effect of process on fiber state and mechanical property.As a result,from orthogonal experiment,those main factors on 100% modulus,on tear strength and on tensile strength were temperature,time and time successively.The optimal condition was at 160?,80 rpm and mixing for 6min.(2)The effects of homebred compatilizer content on interfacial affinity,on fiber state and mechanical property were investigated.Its result shows appropriate compatilizer amount have the interfacial affinity and dispersion improved,while excessive compatilizer would play the role of plasticizer.The interface physical or chemical bond force enhances at the presence of homebred MLPB,and thus the filler apparent network degree would enhance.With the increase of MLPB content,modulus increase while the strength and interfacial adhesion are in agreement with each other,appearing the trend of increasing firstly and then decreasing and reaching its top at 4.5phr.The effects of the ratio of homebred compatilizer content and imported compatilizer content on forming process,and the relationship between interface structure and mechanical property were investigated and analyzed.The result shows the affinity of imported MLPB/AF is better than the affinity of homebred MLPB/AF,and imported MLPB presents faster sprawl process,weaker plastification,more strong effect on dispersion of filler.Accordingly,when imported MLPB reach its higher content,the dynamic loss would be lesser.The comprehensive mechanical properties reach its top at the ratio of 2.5/2(imported MLPB/ homebred MLPB).(3)The relationship between abrasion and composite structure or other properties were independently explored through the composite structure and abrasive phenomenon.As a result,some common laws were obtained.On the one hand,the abrasion and the interface bond strength are closely related: the stronger interfacebond strength is;the better abrasion is.On the other hand,in general,the coarser the abrasion aspect goes,the bigger the particle is or the bigger the included angle between stripe and direction of friction,the poorer the abrasion would be.Compared with unmodified composite,the selected modified composite shows higher tensile strength,higher 100%modulus,higher elongation,higher tear strength and higher abrasion.They improved 16.8%,33.2%,16.3%,34.7% and 18.8%respectively.Moreover,the selected processes grow simpler and the selected materials add the cost lower.Thus,the selected masterbatch was applied for producing tread,and obtained the first engineering tire satisfying the need of this research project,which has been tested in the field.