Leveraging the state of absorbed moisture within a polymer network to identify physical and chemical features of the host material is predicated upon a clear understanding of the interaction between the polymer and a penetrant water molecule; an understanding that has remained elusive. Recent work has revealed that a novel damage detection method that exploits the very low baseline levels of water typically found in polymer matrix composites (PMC) may be a valuable tool in the composite NDE arsenal, provided that a clear understanding of polymer–water interaction can be obtained. Precise detection, location, and possible quantification of the extent of damage can be performed by characterizing the physical and chemical states of moisture present in an in-service PMC. Composite structures have a locally elevated dielectric constant near the damage sites due to a higher fraction of bulk (“free”) water, which has a higher dielectric constant when compared to water molecules bound to the polymer network through secondary bonding interactions. In this study, we aim to get a clear atomistic scale picture of the interactions which drive the dielectric signature variations necessary for tracking damage. Molecular Dynamics (MD) simulations were used to explore the effect of temperature on the state of moisture in two epoxy matrices with identical chemical constituents but different morphologies. The motivation was to understand whether higher polarity binds a greater fraction of moisture even at higher temperatures, leading to suppressed dielectric activity. Consequently, the influence of secondary bonding interactions was investigated to understand the impact of temperature on the absorbed water molecules in a composite epoxy matrix.

中文翻译：

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通过分子模拟探索次要相互作用和温度在受湿气污染的聚合物网络中的作用

通过清楚地理解聚合物与渗透性水分子之间的相互作用，可以利用聚合物网络中吸收的水分的状态来确定主体材料的物理和化学特征。仍然难以理解的理解。最近的工作表明，利用通常在聚合物基质复合材料（PMC）中发现的非常低的基线水含量的一种新颖的损伤检测方法，对于复合无损检测武器库来说可能是一种有价值的工具，前提是对聚合物与水之间的相互作用有清晰的了解。获得。可以通过表征运行中的PMC中存在的水分的物理和化学状态来进行精确的检测，定位以及对损害程度的量化。由于较高比例的散装（“游离”）水，复合结构在损伤部位附近具有局部升高的介电常数，与通过次级键合作用键合到聚合物网络上的水分子相比，复合水具有更高的介电常数。在这项研究中，我们旨在获得相互作用的清晰原子级图片，这些图片驱动了跟踪损伤所必需的介电特征变化。分子动力学（MD）模拟用于探索温度对化学成分相同但形态不同的两种环氧基质中水分状态的影响。目的是了解即使在较高温度下，较高的极性是否也会结合较大比例的水分，从而导致介电活性受到抑制。所以，