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A Novel Method to Characterize Thermal Properties of The Polymer and Gas/Supercritical Fluid Mixture Using Dielectric Measurements
Polymer Testing ( IF 5.0 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.polymertesting.2020.106861
Selina X. Yao , Patrick C. Lee , Heon E. Park , Linda S. Schadler

Abstract Gases or supercritical fluids (SCF) are widely used in polymer science and engineering, as their dissolution into polymeric materials will alter their inherent thermal properties; including melting and crystallization temperatures (Tm and Tc). One possible method to determine these temperatures, at elevated pressures, is to use a high-pressure differential scanning calorimeter (HP-DSC). However, the elevated pressures used in HP-DSC may result in signal instabilities, limiting the testing window for these pressures. This study presents a novel testing system using dielectric measurements to determine the effects of dissolved gas/SCF on the Tm and Tc of polymers. We have developed an instrument to determine the dielectric properties of both polymer/gas and polymer/SCF mixtures, at elevated pressures and temperatures. Using the change in the measured dielectric constant or loss, Tm and Tc were determined. The effects of hydrostatic pressure and plasticization due to dissolved carbon dioxide (CO2) and Helium (He) on the Tm and Tc of high density polyethylene (HDPE) are presented and discussed. Both Tm and Tc increase with pressure and decrease due to plasticization, i.e., pressure and plasticization are competing variables. The dissolution of He, having a low solubility into HDPE, reveals that pressure is the dominant effect. In contrast, the dissolution of CO2, having a high solubility into HDPE, shows that plasticization is predominant.

中文翻译:

一种使用介电测量表征聚合物和气体/超临界流体混合物热性能的新方法

摘要 气体或超临界流体 (SCF) 被广泛应用于高分子科学和工程中,因为它们溶解在高分子材料中会改变其固有的热性能;包括熔化和结晶温度(Tm 和 Tc)。在高压下确定这些温度的一种可能方法是使用高压差示扫描量热计 (HP-DSC)。但是,HP-DSC 中使用的高压可能会导致信号不稳定,从而限制了这些压力的测试窗口。本研究提出了一种新的测试系统,使用介电测量来确定溶解气体/SCF 对聚合物 Tm 和 Tc 的影响。我们开发了一种仪器,可以在升高的压力和温度下测定聚合物/气体和聚合物/SCF 混合物的介电特性。使用测量的介电常数或损耗的变化,确定 Tm 和 Tc。介绍和讨论了静水压力和由溶解的二氧化碳 (CO2) 和氦气 (He) 引起的塑化对高密度聚乙烯 (HDPE) 的 Tm 和 Tc 的影响。Tm 和Tc 均随压力增加而因塑化而降低,即压力和塑化是相互竞争的变量。He 在 HDPE 中的溶解度较低,表明压力是主要影响。相比之下,在 HDPE 中具有高溶解度的 CO2 的溶解表明塑化占主导地位。介绍和讨论了静水压力和由溶解的二氧化碳 (CO2) 和氦气 (He) 引起的塑化对高密度聚乙烯 (HDPE) 的 Tm 和 Tc 的影响。Tm 和Tc 均随压力增加而因塑化而降低,即压力和塑化是相互竞争的变量。He 在 HDPE 中的溶解度较低,表明压力是主要影响。相比之下,在 HDPE 中具有高溶解度的 CO2 的溶解表明塑化占主导地位。介绍和讨论了静水压力和由溶解的二氧化碳 (CO2) 和氦气 (He) 引起的塑化对高密度聚乙烯 (HDPE) 的 Tm 和 Tc 的影响。Tm 和Tc 均随压力增加而因塑化而降低,即压力和塑化是相互竞争的变量。He 在 HDPE 中的溶解度较低,表明压力是主要影响。相比之下,在 HDPE 中具有高溶解度的 CO2 的溶解表明塑化占主导地位。
更新日期:2020-12-01
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