In this work, we propose a compound electret-system with improved hydrophobicity and charge stability in water and at elevated temperatures by bonding a solid fluorinated-ethylene-propylene (FEP) film to a porous polytetrafluoroethylene (PTFE) film. Two bonding approaches are investigated, the electrostatic-bonding and melting-bonding, to laminate the FEP and PTFE layers. Experimentally, the compound system shows improved hydrophobicity and charge stability both in water and elevated temperatures compared with the single layer FEP. The contact angles of the compound samples with electrostatic-bonding and melting-bonding are 139 and 124°, respectively. After immersion in water for 16 hours, surface potentials of −406 and −105 V are retained in the samples with electrostatic-bonding and melting-bonding, respectively, which exceeds the single layer FEP. The open circuit thermally stimulated discharge (TSD) current spectra show that the negatively charged electrostatic-bonding sample has a broad positive current peak at 202 °C, while for the melting-bonding sample charged under the same conditions, shows two current peaks at 231 °C and 269 °C. The enhancement of hydrophobicity and charge stability in water for compound systems must be attributed to the specific geometry on the surface of porous PTFE layer, and the improved thermal stability of charges in melting-bonding compound system could be due to the deep charge traps at the interface between FEP and porous PTFE layers generated during heat-pressing process.

中文翻译：

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具有改进的疏水性和电荷稳定性的复合驻极体系统

在这项工作中，我们通过将固体氟化乙烯丙烯 (FEP) 膜与多孔聚四氟乙烯 (PTFE) 膜结合，提出了一种复合驻极体系统，该系统在水中和高温下具有改善的疏水性和电荷稳定性。研究了两种粘合方法，静电粘合和熔融粘合，以层压 FEP 和 PTFE 层。实验上，与单层 FEP 相比，该化合物系统在水中和高温下均显示出改进的疏水性和电荷稳定性。静电键合和熔融键合的化合物样品的接触角分别为139°和124°。在水中浸泡 16 小时后，-406 和 -105 V 的表面电位分别保留在静电键合和熔融键合的样品中，这超过了单层 FEP。开路热刺激放电 (TSD) 电流谱表明，带负电荷的静电粘合样品在 202 °C 处具有较宽的正电流峰值，而在相同条件下充电的熔融粘合样品在 231°C 处出现两个电流峰值。 °C 和 269 °C。复合体系在水中疏水性和电荷稳定性的增强必须归因于多孔 PTFE 层表面的特定几何形状，而熔融键合复合体系中电荷热稳定性的提高可能是由于在FEP 与热压过程中产生的多孔 PTFE 层之间的界面。开路热刺激放电 (TSD) 电流谱表明，带负电荷的静电粘合样品在 202 °C 处具有较宽的正电流峰值，而在相同条件下充电的熔融粘合样品在 231°C 处出现两个电流峰值。 °C 和 269 °C。复合体系在水中疏水性和电荷稳定性的增强必须归因于多孔 PTFE 层表面的特定几何形状，而熔融键合复合体系中电荷热稳定性的提高可能是由于在FEP 与热压过程中产生的多孔 PTFE 层之间的界面。开路热刺激放电 (TSD) 电流谱表明，带负电荷的静电粘合样品在 202 °C 处具有较宽的正电流峰值，而在相同条件下充电的熔融粘合样品在 231°C 处出现两个电流峰值。 °C 和 269 °C。复合体系在水中疏水性和电荷稳定性的增强必须归因于多孔 PTFE 层表面的特定几何形状，而熔融键合复合体系中电荷热稳定性的提高可能是由于在FEP 与热压过程中产生的多孔 PTFE 层之间的界面。