Effect Of Liquid Rubber On Isoprene Rubber And Butadiene Rubber Blends

Liquid rubber(LIR-390)is a low molecular weight block copolymer(PI-b-PB).LIR-390 as a good plasticizer for rubber processing can improve the processing properties of rubber,and used as compatibilizer can enhance the mechanical properties of rubber.In this thesis,LIR-390 acted as the compatibilizer of blend system of isoprene rubber(IR)/ butadiene rubber(BR)was used to study the effects of asymmetric block copolymers on the structure and performance of IR/BR rubber blends by using atomic force microscopy(AFM),HAAKE rotational rheometer,dynamic mechanical analyzer(DMA),fatigue crack growth tester,rubber processing analyzer(RPA),universal testing machine and scanning electron microscope(SEM).The main results are as following:1.The IR/BR binary blends were used as the research object to study the structure and properties of IR/BR blend rubber with four different proportions.The results showed that the IR/BR blending presented the single continuous phase structure when the proportions were 80/20 and 70/30,while the double continuous phase structure was emerged at the IR/BR proportions of 60/40 and 50/50.Moreover,the tensile properties of blend rubber showed a downward trend with the growth of the proportion of BR due to the worse mechanical properties of pure BR than IR.The anti-fatigue crack growth performance of double continuous phase structure was better than that of single continuous phase at the low tear energy(less than 1300 J/m2),but the opposite result was presented at high tear energy.2.The blend rubber with the proportion of 70/30 was selected to further study the influence of LIR-390 on the structure and performance of IR/BR.The study found that the addition of LIR-390 was conducive to the decrease of the size of dispersed phase(BR),while the blending sequence had no effect on the ternary blends of LIR-390/IR/BR.In addition,the excess addition of LIR-390 would cause the increase of BR phase size.The storage modulus(G')of blend rubber increased with the decreasing amount of LIR-390.The appropriate amount of LIR-390 was beneficial to the improvement of anti-fatigue crack growth performance of blend rubber,but the excess LIR-390 would accelerate the growth rate of crack.3.The structure and performance of LIR-390 on the IR / BR after the addition of carbon black was investigated.The results showed that LIR-390 can make carbon black distribute more uniformly in the IR/BR blend rubber and carbon black with smaller size of aggregates.The content of bound-rubber increased with the increase of content of liquid rubber.The addition of LIR-390 was conducive to the improvement of tensile properties and anti-fatigue crack growth performance of blend rubber.Furthermore,the Payne effect of blend rubber weakened with the increase of LIR-390 content.