Kar Suvrajyoti, Cuddigan Julie L, Greenfield Michael L
Department of Chemical Engineering, University of Rhode Island, Kingston, RI 02881, USA.
Polymers (Basel). 2023 Mar 14;15(6):1441. doi: 10.3390/polym15061441.
This work develops a probability-based numerical method for quantifying mechanical properties of non-Gaussian chains subject to uniaxial deformation, with the intention of being able to incorporate polymer-polymer and polymer-filler interactions. The numerical method arises from a probabilistic approach for evaluating the elastic free energy change of chain end-to-end vectors under deformation. The elastic free energy change, force, and stress computed by applying the numerical method to uniaxial deformation of an ensemble of Gaussian chains were in excellent agreement with analytical solutions that were obtained with a Gaussian chain model. Next, the method was applied to configurations of cis- and trans-1,4-polybutadiene chains of various molecular weights that were generated under unperturbed conditions over a range of temperatures with a Rotational Isomeric State (RIS) approach in previous work (, , 129-138). Forces and stresses increased with deformation, and further dependences on chain molecular weight and temperature were confirmed. Compression forces normal to the imposed deformation were much larger than tension forces on chains. Smaller molecular weight chains represent the equivalent of a much more tightly cross-linked network, resulting in greater moduli than larger chains. Young's moduli computed from the coarse-grained numerical model were in good agreement with experimental results.
本工作开发了一种基于概率的数值方法，用于量化承受单轴变形的非高斯链的力学性能，旨在能够纳入聚合物 - 聚合物和聚合物 - 填料相互作用。该数值方法源于一种概率方法，用于评估变形下链端到端向量的弹性自由能变化。通过将数值方法应用于高斯链系综的单轴变形来计算的弹性自由能变化、力和应力，与用高斯链模型获得的解析解非常吻合。接下来，该方法应用于在先前工作中通过旋转异构态（RIS）方法在一系列温度下在无扰条件下生成的各种分子量的顺式和反式1,4 - 聚丁二烯链的构型（，，129 - 138）。力和应力随变形增加，并且进一步证实了对链分子量和温度的依赖性。垂直于施加变形的压缩力远大于链上的拉力。较小分子量的链相当于交联紧密得多的网络，导致模量比较大的链更大。从粗粒度数值模型计算得到的杨氏模量与实验结果吻合良好。
