Bead-free and beaded electrospun phase change fibers: A comparative study

Abstract

Hydrocarbon (n-eicosane)-loaded poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) blended fibers exhibiting bead-free and beaded morphologies were fabricated by means of the electrospinning technique using chloroform as the processing solvent and systematically compared in respect to their phase change behavior. Their morphological characteristics were determined by Scanning Electron Microscopy (SEM), which revealed their highly porous structures, while their chemical composition and structural properties were examined by Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) spectroscopy, respectively. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) were implemented for obtaining information on the materials’ thermal properties. The heating–cooling cycles up to 48 °C revealed that in both sample series (i.e. bead-free and beaded fibers), the melting temperature increases by increasing the n-eicosane content. The temperature of the first crystallization peak (higher temperature) showed a minimal variation, while the temperature of the second peak (lower temperature) increased upon increasing the n-eicosane content. All investigated materials exhibited excellent repeatability in consecutive heating–cooling cycles, with significantly low supercooling and high enthalpy values. Interestingly, regardless of their morphology (bead-free or beaded), both series were found to be suitable as phase change materials for a wide range of n-eicosane content values. Additionally, the supercooling values recorded in the two series with the same n-eicosane content (10–20%) were nearly indistinguishable.