Abstract Few studies have examined the process dependence of the pressure–specific volume–temperature (pvT) behavior of polymers. Especially, the specific volume variation during heating is often ignored, but for certain processing techniques such as plastic welding and additive manufacturing, special consideration should be given. In this study, a new pvT model was proposed to determine the specific volume evolution of polymers during cooling and heating processes. The process dependence of pvT behavior of polymers was discussed in theory, and the influences of starting temperature and cooling/heating rates were considered in the modeling. The pvT behavior of a semi-crystalline polymer, polypropylene (PP), was measured. Mathematical model parameters were determined through the fitting of the experimental pvT data. The fitted results were in good agreement with the experimental data, which showed that the proposed model is accurate and effective. The R2 value of 99.82% and the average absolute percent deviation of 0.21% were obtained. The process dependent pvT model is simple and has broad application prospects in polymer physics and polymer processing.

中文翻译：

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考虑到冷却和加热过程的依赖性，聚合物的压力比体积-温度行为建模

摘要 很少有研究检查聚合物的压力-比体积-温度 (pvT) 行为的过程依赖性。特别是加热过程中的比容变化往往被忽略，但对于某些加工技术，如塑料焊接和增材制造，应给予特殊考虑。在这项研究中，提出了一种新的 pvT 模型来确定聚合物在冷却和加热过程中的比体积演变。从理论上讨论了聚合物 pvT 行为的过程依赖性，并在建模中考虑了起始温度和冷却/加热速率的影响。测量了半结晶聚合物聚丙烯 (PP) 的 pvT 行为。通过拟合实验 pvT 数据来确定数学模型参数。拟合结果与实验数据吻合较好，表明所提出的模型是准确有效的。获得了 99.82% 的 R2 值和 0.21% 的平均绝对百分比偏差。过程相关的 pvT 模型简单，在高分子物理和高分子加工中具有广阔的应用前景。