聚(VDF-co-TrFE)共聚物中热效应的分析与分子动力学结合模型

IF 2.702 Q1 Materials Science
Vadim I. Sultanov, Vadim V. Atrazhev, Dmitry V. Dmitriev
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引用次数: 1

摘要

建立了铁电聚偏二氟乙烯-共三氟乙烯共聚物(聚(VDF-co-TrFE))热效应的分析与分子动力学相结合的模型。该模型计算绝热电场变化Δ T下聚合物极化P和温度变化作为温度的函数。该模型的分析部分基于朗道现象学理论,该理论适用于模拟聚合物晶体从铁电β相到准电构象紊乱(条件)相的一阶相变。通过对聚(VDF-co-TrFE)完美晶体的分子动力学模拟,标定了自由能泛函的参数。模型考虑了实际非晶聚合物中各种晶体的随机取向和相变温度的散射。模型预测与实验数据的比较表明,模型对Δ T的值高估了约2.5倍。我们将这种差异归因于真实聚合物晶体中存在的结构缺陷,与我们分子动力学方法模拟的完美晶体相比,这减少了相变下的熵变。模型计算的Δ T的理论极限表明,与目前观测到的Δ T的实验值相比,Δ T最多可以提高3倍。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Combined analytical and molecular dynamics model of electrocaloric effect in poly(VDF-co-TrFE) copolymer

Combined analytical and molecular dynamics model of electrocaloric effect in poly(VDF-co-TrFE) copolymer

A combined analytical and molecular dynamics model for the electrocaloric effect in ferroelectric poly(vinylidene difluoride-co-trifluoroethylene) copolymer (poly(VDF-co-TrFE)) is developed. The model calculates the polymer polarization, P , and temperature change under adiabatic electric field variation, Δ T , as functions of temperature. An analytical component of the model is based on the Landau phenomenological theory adapted for modeling of the first order phase transitions in a polymer crystal from a ferroelectric β phase to a paraelectric conformationally disordered (condis) phase. Parameters of the free energy functional are calibrated through molecular dynamics simulations of poly(VDF-co-TrFE) perfect crystal. Random orientation and the scatter of the phase transition temperature for various crystallites in a real amorphous-crystalline polymer are incorporated into the model. Comparison of the model prediction with experimental data shows good agreement for P T while the model overestimates the value of Δ T by approximately 2.5 times. We attribute this discrepancy to the presence of structural defects in real polymer crystallites, which reduces the entropy change under the phase transition compared to the perfect crystal simulated in our molecular dynamics approach. The theoretical limit of Δ T calculated by the model indicates that Δ T can be increased up to 3 times compared to the currently observed experimental value of Δ T .

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来源期刊
CiteScore
5.20
自引率
0.00%
发文量
0
审稿时长
1.8 months
期刊介绍: Part A: Polymer Chemistry is devoted to studies in fundamental organic polymer chemistry and physical organic chemistry. This includes all related topics (such as organic, bioorganic, bioinorganic and biological chemistry of monomers, polymers, oligomers and model compounds, inorganic and organometallic chemistry for catalysts, mechanistic studies, supramolecular chemistry aspects relevant to polymer...
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