Supercooling suppression and mechanical property improvement of phase change nanofibers by optimizing core distribution

Phase change fibers (PCFs) as a kind of composite material, the composition and spatial distribution of each phase have a great influence on its thermal and mechanical properties. In this article, PCFs with polyvinylpyrrolidone (PVP), polyvinyl butyral (PVB), and polyacrylonitrile (PAN) as sheath and 30% octadecane kerosene as core were prepared by coaxial electrospinning. It was found that octadecane had the highest supercooling degree when it was encapsulated in PVB. Thus, we used pure octadecane, 30% octadecane of isopropanol, chloroform, and kerosene solutions as core solutions, adjusted the fine structure of octadecane in PVB sheath, and four kinds of PCFs with different octadecane particle size and spacing were prepared. Successfully reduced the supercooling degree of octadecane. To compare the mechanical properties of the four fibers. It was found that the composite fiber obtained by using isopropanol as octadecane solvent had the most comprehensive mechanical performance. To find a universal method to control the distribution structure of phase change materials (PCMs) in fibers by coaxial electrospinning, we used PAN and PVDF as the sheath solution, pure octadecane, 30% octadecane in isopropanol, chloroform, petroleum ether, and kerosene solutions as a core solution to prepare the PCFs. Characterization results and analysis of the properties of solutions showed that only when the viscosity of the core and sheath solution was relatively low, it could obtain the bamboo-like structured fibers. And continuous core-sheath structured fibers could be obtained in two situations. First, the low viscosity of sheath solution and high viscosity of core solution; second, the high viscosity of sheath solution.