两芯/三芯核壳结构定形相变复合纤维的构建、相变协同及传热增强机理研究

The form-stable phase change composite fibers with dual and triple core-shell structure consisting of two or three types of fatty acid binary/multiple eutectics and polymer fibers are fabricated by dual-core and tripe-core compound jet electrospinning. In these phase change composite fibers, the fatty acid binary/multiple eutectics serve as solid-liquid phase change materials and the polymer fibers act as supporting materials. The inherent relationships between morphological structure of form-stable phase change composite fibers and rheological properties of electrospinning solutions as well as spinning conditions are studied in this project. The formation mechanism of composite fibers and regulation of morphological structure are summarized. The effect of distribution of fatty acid eutectics in the composite fibers on their thermal energy storage properties is discussed, and their solid-liquid phase change mechanism and phase change synergistic mechanism between different components are also revealed. The method of adjusting the thermal energy storage properties of composite fibers is summarized. The thermal energy storage and release rates of phase change composite fibers are enhanced by addition of nanoparticles with high thermal conductivity (such as boron nitride nanoparticles, silicon carbide nanoparticles and alumina nanoparticles). The influences of the types, content and distribution area of the selected nanoparticles in the composite fibers on the formation of continuous heat conduction network structure are explored and then the mechanism of heat transfer enhancement is demonstrated. Morphological structure, thermal and physical properties of composite fibers before and after thermal cycling are systemically analyzed, confirming that the prepared form-stable phase change composite fibers have excellent thermal stability and sustainability.

采用两芯和三芯复合射流静电纺丝技术，以两种或三种脂肪酸二元/多元低共熔物为芯层相变材料，以聚合物纤维基体为皮层支撑材料，构筑两芯和三芯核壳结构定形相变复合纤维。研究纺丝液流变学性能和纺丝条件与定形相变复合纤维结构构建之间的内在联系，阐明复合纤维的成形机理和结构调控规律。探讨脂肪酸低共熔物在复合纤维芯层的分布构象对其相变储热性能的影响，揭示其固-液相变机理以及不同组分之间的相变协同作用机制，总结调控复合纤维储热性能的有效方法。通过添加高导热系数的纳米粒子（如纳米氮化硼、纳米碳化硅和纳米氧化铝）改善定形相变复合纤维体系的整体传热性能，探讨纳米粒子的种类、含量以及分布区域对连续导热网链结构构建的影响规律，揭示其传热增强机理。对热循环前后复合纤维的结构与热物理性能进行综合评价，证实其可循环使用的稳定性。

相变储能技术是利用相变材料的相变过程进行热能的储存和释放，是节能技术研究的重要方面。为了研制出相变温度在室温范围的储能材料，满足部分工程应用领域的实际需求，脂肪酸二元/多元低共熔物被相续开发。但是脂肪酸低共熔物作为固-液相变储能材料存在液相渗漏和导热系数低的缺点，同时为了调控其相变温度能够满足更广泛领域的应用需求，本项目采用静电纺丝方法，以脂肪酸低共熔物为相变材料，以聚合物纤维基体（如聚丙烯腈、聚苯乙烯）为支撑材料，制备定形相变复合纤维膜。系统研究纺丝液性能和纺丝条件与定形相变复合纤维膜结构构建之间的内在联系，阐明复合纤维膜的成形机理和结构调控规律。探讨脂肪酸低共熔物在复合纤维基体内的分布对其相变储热性能的影响，揭示其固-液相变机理以及不同组分之间的相变协同作用机制，总结调控复合纤维储热性能的有效方法。通过添加高导热系数的纳米粒子（如纳米氮化硼、纳米碳化硅和纳米氧化铝）改善定形相变复合纤维体系的整体传热性能，探讨纳米粒子的种类、含量以及分布对连续导热网链结构构建的影响规律，揭示其传热增强机理。同时也分析添加纳米粒子对定形相变复合纤维形貌结构特征以及热物理性能的影响。对热循环前后定形相变复合纤维的结构与热物理性能进行综合评价，证实其可循环使用的稳定性。形貌结构观测结果表明定形相变复合纤维的平均纤维直径分布约在300-700nm之间。储热性能分析结果表明由于不同种类脂肪酸低共熔物之间的相变协同作用，研制的定形相变储能复合纤维膜可调控的相变温度和相变焓值区间更广，分别约在5-35℃和40-156kJ/kg之间，实际应用灵活性更强。通过添加高导热系数的纳米粒子，在相变复合纤维膜中形成了贯穿于纤维体系的连续导热网链结构，实现复合纤维膜整体的传热增强，进而提高热能储存与释放速率。研制的定形相变储能复合纤维膜可望应用于调控温度需在室温范围的应用领域，如储能调温纤维及其纺织品等。