缠结拓扑限制作用对凝胶杆屈曲的影响

当前对聚合物凝胶失稳现象的研究大多是基于Flory-Rehner弹性凝胶理论，并未考虑凝胶网络链段相互缠绕引起的物理交联对凝胶弹性网络自由能的影响．因此，本文采用了一个新的，包含网络缠结拓扑限制作用的凝胶自由能函数，在此基础上计算交联网链数密度与滑动环数密度的比值、不可伸展参数、滑移参数对聚合物凝胶的折合增量模量的影响，并给出了不同长细比凝胶杆的临界屈曲应力．研究结果表明：交联网链数密度与滑动环数密度的比值、不可伸展参数越大，增量模量越大，而滑移参数越大，增量模量越小；凝胶杆的长细比越大，临界屈曲应力越小．

The Influence of Entanglements on the Buckling of a Polymeric Gel Bar

The buckling behavior of polymeric gel is often described in terms of the Flory–Rehner framework, in which the influence of entanglements is not taken into account. In this paper we used a new free energy function in which the influence of entanglements had been taken into account. By means of this free energy function, we calculated the influence of the ratio of the concentration of slip links and the concentration of crosslinks, the inextensibility parameter, the slippage parameter on the incremental modulus of polymeric gel. The critical buckling stresses of a polymeric gel bar with various slenderness ratio were also calculated. The results show that in the entangled state, the higher of the ratio of the concentration of slip links and the concentration of crosslinks, the bigger of the incremental modulus, the value of inextensibility parameter is the same while the value of slippage parameter is opposite. The critical buckling stress of a gel bar with higher slenderness ratio is smaller.