1,2-聚丁二烯接枝丁苯共聚物的流变性能

用双筒毛细管流变仪研究了丁苯共聚物支链含量不同的3种接枝1,2-聚丁二烯的流变性能,并与线型1,2-聚丁二烯进行了比较。结果表明,丁苯共聚物的接枝使得1,2-聚丁二烯的数均分子量减小,重均分子量增大,分子量分布变宽;接枝前后1,2-聚丁二烯的1,2-结构摩尔分数均大于80%,都属于高乙烯基聚丁二烯。在80～120℃内,接枝前后1,2-聚丁二烯的表观黏度均随温度的升高而降低,接枝后的黏流活化能明显增大;随丁苯共聚物接枝量的增加,接枝橡胶的黏流活化能逐渐减小,黏温敏感性减弱。丁苯共聚物的接枝对1,2-聚丁二烯黏度剪切敏感性的影响比较复杂,在150～3 000 s-1的剪切速率内,接枝前后1,2-聚丁二烯的表观黏度均随剪切速率的增加而降低;线型及接枝质量分数为5%的1,2-聚丁二烯的非牛顿指数明显降低,接枝质量分数为1%的非牛顿指数增大,更接近牛顿流体行为,而接枝质量分数为7%的非牛顿指数基本不变。在温度为80℃和100℃时,于相同的剪切速率下,随着丁苯共聚物接枝量的增加,3种接枝橡胶的表观黏度有先降低后升高的趋势,其中接枝质量分数为7%的1,2-聚丁二烯的表观黏度最大。

Rheological property of 1,2-polybutadiene grafted styrene-butadiene copolymer

The 1,2-polybutadiene grafted styrene-butadiene copolymer(1,2-PBR-g-SB) with different content of SB was synthesized.The rheological property of the grafted copolymers was studied by double capillary rheometer and compared with that of linear 1,2-polybutadiene(1,2-PBR).The results showed that the grafted SB could decrease the numbe-average molecular weight and increase the weight-average molecular weight and increase the weight of 1,2-PBR,and broaden the molecular weight distribution.Before and after grafted,1,2-PBR both had high content vinyl(over 80%),and the apparent viscosity of 1,2-PBR decreased with temperature rised from 80 ℃ to 120 ℃.After grafted,the viscous flow activation energy of 1,2-PBR increased evidently,but it reduced gradually,and its sensitivity of viscosity to temperature weakened with increasing the grafted SB.However,the effect of grafted SB on the sensitivity of viscosity to shearing of 1,2-PBR was more complex,before and after grafted,the apparent viscosity of 1,2-PBR decreased with increasing shear rate from 150 s-1 to 3 000 s-1.The non-Newtonian index of the linear 1,2-PBR and 1,2-PBR-g-SB with SB mass fraction 5% decreased obviously,but with SB mass fraction 1% increased,which was more close to Newtonian fluid,while with SB mass fraction 7% remained almost no changes.At the temperature of 80 ℃,100 ℃,and the same shear rate,the apparent viscosity of three kinds of 1,2-PBR-g-SB decreased first and then increased with increasing the grafted SB,and the 1,2-PBR-g-SB with SB mass fraction 7% had the highest viscosity.