Abstract: Conventional textiles cannot effectively dissipate heat in frequent high temperature weather caused by global warming, which cannot meet the needs of people or objects for thermal regulation. Textiles with thermal conductivity have received extensive attention because they can transfer the heat of the human body or objects directly to the external environment for realizing heat regulation through heat conduction in a simple and fast way. Based on this, textiles with thermal conductivity are widely developed through various methods such as fiber blending, coating, and filling. However, there still exist many limitations of complicated preparation process, easy shedding and uneven distribution of material with thermal conductive, and insufficient improvement of thermal conductivity.
To improve the thermal conductivity of fiber materials, we, starting from fine structure regulation of thermal conductivity networks, selected polyvinylidene fluoride (PVDF) and Ag flakes with different scales as the substrate and thermal conductivity filler, designed the connecting structures of mix-scaled Ag sheets in the fiber membrane, and used electrospinning technology to construct a PVDF/Ag fiber membrane with a three-dimensional interconnected thermal conductivity network in one step. The morphologies and chemical structures of the PVDF/Ag fiber membrane were characterized by field emission scanning electron microscope with EDS spectrometer and X-ray photoelectron spectroscopy. The distribution and formed network structure of mix-scaled Ag flakes in the fiber were analyzed through morphology observation. The water contact angle and mechanical properties of the fiber membrane were recorded by droplet contact angle measuring instrument and strength testing instrument. The thermal conductivity and mechanism of PVDF/Ag fiber films under different Ag flake sizes, Ag flake contents, and compression degrees were researched by using a thermal conductivity meter. Finally, the practical application on thermal conductivity of PVDF/Ag fiber membranes before and after compression was tested through a heating table and temperature by measuring instruments. The results show that the addition of mixed-size Ag flakes can form a three-dimensional network structure with internal connectivity of a single fiber and external connectivity between fibers and their connectivity between fibers gradually enhances with the content increase of large-sized Ag flakes. When the Ag content is four times that of PVDF polymer, the PVDF/Ag fiber membrane with a three-dimensional interconnected network structure exhibits excellent thermal conductivity, with a thermal conductivity coefficient of 0.1038 W/(mK), which is 61% higher than that of pure PVDF fiber membranes. After compression treatment, the thermal conductivity of the PVDF/Ag fiber membrane increases to 8.693 W/(mK), which is 83.6 times higher than before compression. When the PVDF/Ag fiber membrane before and after compression is placed on a 37 ℃ hot bench, both show a fast temperature rise rate, demonstrating good practical application ability. Also, the PVDF/Ag fiber membrane exhibits excellent mechanical and hydrophobic properties.
Compared to existing textiles with thermal conductivity, the PVDF/Ag fiber membrane constructed in this paper with a three-dimensional interconnected thermal-conductive network not only exhibits better thermal conductivity, but also has good mechanical and hydrophobic properties, demonstrating excellent application potential in related fields such as multi-functional textiles and other flexible thermal conductive materials. Furthermore, Ag sheets also have other excellent functions such as antibacterial and electrical conductivity, which is of great guiding significance for the further development of multifunctional textiles and flexible materials.

Key words: electrospinning, PVDF, Ag flakes, mixed size, three-dimensional interconnected network structure, fiber membrane, thermal conductivity

摘要： 为了提高纤维材料的导热性能，选择不同尺寸的Ag片作为导热填料，通过静电纺丝技术一步构建了具有三维互通导热网络的PVDF/Ag纤维膜，对其形貌和化学结构进行表征，研究Ag片尺寸、Ag片含量、压缩程度对其导热性能的影响，并对其实际应用能力进行评估。结果表明：加入混合尺寸Ag片，能够形成单根纤维内部连通和纤维之间外部连通的三维互通网络结构。具有该结构的PVDF/Ag纤维膜表现出优异的导热性能，导热系数达0.1038 W/(mK)，比纯PVDF纤维膜提高了61%；将其压缩处理后，导热系数进一步提升至8.693 W/(mK)，是压缩前的83.6倍。此外，三维互通网络的PVDF/Ag纤维膜还展示出优异的力学应用能力和疏水性能。 研究结果对进一步开发多功能集合的纺织品及柔性材料具有重要的参考价值。

关键词: 静电纺丝, PVDF, Ag片, 混合尺度, 三维互通网络结构, 纤维膜, 导热性能