发表机构
Université Paris-Saclay, CEA, Service de Recherches en Corrosion et Comportement des Matériaux, SRMP; PIMM, Arts et Métiers Institute of Technology, CNRS, CNAM, HESAM University（巴黎萨克雷大学、法国原子能和替代能源委员会、腐蚀与材料行为研究服务处; 巴黎艺术与工艺博物馆实验室、国立高等工艺学院、法国国家科学研究中心、国立 Conservatoire des Arts et Métiers、HESAM 大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过多尺度计算（量子模拟与分子动力学）研究含辐射氧化缺陷的半结晶聚乙烯的介电响应，揭示缺陷类型对介电常数和损耗的影响，其中酮基缺陷损耗最大。
AI 中文摘要
聚合物被广泛用作功能性绝缘材料，但预测其介电行为具有挑战性，因为多种机制在不同空间和时间尺度上共同作用于其响应。在聚乙烯（PE）这一最常见的聚合物中，必须同时考虑电子、原子和介观尺度的动力学。本研究开发了半结晶聚乙烯模型，并采用多尺度方法进行研究。量子模拟用于描述介电响应中的电子和振动贡献，而经典分子动力学模拟则捕捉了室温下聚合物链的行为，频率低至10-100 MHz范围。研究聚焦于辐射氧化缺陷对聚乙烯介电性能的影响。量子计算揭示了电子和振动贡献如何依赖于这些缺陷周围的局域原子环境。与分子动力学结果的比较突显了温度对静态介电常数的影响。结构分析进一步评估了每种缺陷类型对PE结晶度的影响。偶极相关函数分析表明，不同缺陷之间以及缺陷与聚合物基体之间的相互作用方式不同，影响介电常数和介电损耗峰。对于所有缺陷类型，缺陷-缺陷相互作用对介电响应的贡献最大。虽然大多数氧化基团与PE基体表现出正耦合，但醇缺陷表现出负的交叉相关，部分抵消了其对介电性能的影响。我们的结果还表明，在所研究的缺陷中，酮基产生的介电损耗最大。
英文摘要
Polymers are widely used as functional insulating materials, but predicting their dielectric behavior is challenging because multiple mechanisms, acting across different spatial and temporal scales, contribute to their response. In polyethylene (PE), one of the most common polymers, electronic, atomic, and mesoscale dynamics must all be considered. In this work, semicrystalline models of polyethylene were developed and investigated using a multiscale approach. Quantum simulations were employed to describe electronic and vibrational contributions to the dielectric response, while classical molecular dynamics simulations captured the behavior of polymer chains at room temperature and frequencies down to the 10-100 MHz range. The study focuses on the impact of radio-oxidation defects on the dielectric properties of polyethylene. Quantum calculations reveal how electronic and vibrational contributions depend on the local atomic environment surrounding these defects. Comparison with molecular dynamics results highlights the influence of temperature on the static dielectric constant. Structural analyses further assess the effect of each defect type on PE crystallinity. Analysis of dipolar correlation functions shows that different defects interact with one another and with the polymer matrix in distinct ways, affecting permittivity and dielectric loss peaks. For all defect types, defect-defect interactions provide the largest contribution to dielectric response. While most oxidized groups exhibit positive coupling with the PE matrix, alcohol defects display a negative cross-correlation, partially offsetting their impact on the dielectric properties. Our results also show that ketone groups produce the largest dielectric loss between the defects studied.
Comments36 pages, 11 figures
