丁基橡胶/聚异丁烯交联体系的黏弹行为

Viscoelastic Behaviors of Cross-Linked Butyl Rubber/Polyisobutene System

选用聚异丁烯-异戊二烯共聚物橡胶(IIR)和聚异丁烯(PIB)为原材料,研究了PIB含量与相对分子质量、IIR中异戊二烯含量和交联剂含量对IIR/PIB交联体系黏弹行为的影响。研究结果显示,完全交联的IIR体系几乎不发生应力松弛;添加不可交联的PIB显著降低了IIR交联后的模量,PIB相对分子质量越高,对模量的影响越小;IIR中异戊二烯含量和交联剂含量增加会使交联速率和交联密度提高,其中异戊二烯含量越高,交联剂含量变化对交联IIR/PIB黏弹性的影响越大。PIB质量分数为50%时,IIR/PIB体系损耗模量(G′′)在交联过程中的变化与交联密度、PIB性质密切相关:交联反应初期,G′′随弹性模量(G′)的提高而下降,交联反应后期则随着交联密度的上升而增加,且低分子量PIB和高分子量PIB体系的G′′值分别在G′=120~150 kPa和220~270 kPa时出现最低值;G′′~G′曲线在高交联密度下逐渐实现归一化,揭示了非交联分子链在交联IIR网络中的松弛行为。同时,PIB在交联IIR网络中松弛导致聚合物体系模量降低,但其归一化G(t)~t曲线几乎完全重合。

Selecting butyl rubber(IIR)and polyisobutene(PIB)as raw material,the influence of PIB content and molecular weight,crosslinking agent,double bonds of IIR on the rheological behaviors of the crosslinked IIR/PIB systems was studied.The results show that completely crosslinked IIR hardly relax,and adding PIB into IIR,which cannot be crosslinked,reduces the modulus of crosslinked composites greatly.And,the PIB with high molecular weight has less effect.With the increasing content of crosslinking agent and double bonds,both the crosslinking rate and crosslinking density increase,and the crosslinking agent has greater effect on crosslinking density when IIR has a higher content of double bond.With the PIB mass fraction of 50%,the loss modulus(G′′)is closely related to crosslinking density and molecular weight of PIB,G′′decreases greatly with G′at the beginning.Then,G′′increases with G′with the minimum G′′of PIB with low and high molecular weight at G′=120~150 kPa and G′=220~270 kPa respectively.G′′~G′curve is normalized at high crosslinking density,which reflects the relaxation behaviors of non-crosslinked molecules in crosslinked IIR network.PIB in crosslinked IIR network can relax and result in low modulus;but the normalized G(t)~t curves are almost completely overlapped.