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The eight kinds of fatty acid binary and ternary eutectics such as capric–lauric acid (CL), capric–myristic acid (CM), capric–palmitic acid (CP), capric–stearic acid (CS), capric–lauric–palmitic acid (CLP), capric–myristic–palmitic acid (CMP), capric–myristic–stearic acid (CMS), and capric–palmitic–stearic acid (CPS) were selected as solid–liquid PCMs in this paper. The innovative electrospun fatty acid binary eutectic/polystyrene/fatty acid ternary eutectic (i.e., CL/PS/CLP, CM/PS/CLP, CP/PS/CLP, CS/PS/CLP, CL/PS/CMS, CM/PS/CMS, CP/PS/CMS, CS/PS/CMS, CL/PS/CPS, CM/PS/CPS, CP/PS/CPS and CS/PS/CPS) and fatty acid ternary eutectic/polystyrene/fatty acid ternary eutectic (i.e., CLP/PS/CMP, CLP/PS/CMS, CLP/PS/CPS, CMP/PS/CMS, CMP/PS/CPS and CMS/PS/CPS) form-stable phase change composite fibrous membranes (PCCFMs) were fabricated by co-electrospinning. The morphological structure, phase change temperatures, and enthalpies were investigated by scanning electron microscope (SEM) and differential scanning calorimetry (DSC), respectively. The SEM images showed that the PS-based phase change composite fibers were collected to form form-stable PCCFMs with the average fiber diameter of about 335–640 nm. The DSC analysis indicated that the melting peak temperatures of electrospun PS-based form-stable PCCFMs can be adjusted to 15–25 °C with the temperature interval of 1 °C by combining the both of fatty acid binary and ternary eutectics into the PS supporting fibers. These PS-based form-stable PCCFMs can be recommended for potential low-temperature thermal energy storage applications to regulate temperature and satisfy the human thermal comfortability. [ABSTRACT FROM AUTHOR]

The novel quinary fatty acid eutectic (CA-LA-MA-PA-SA) of capric acid, lauric acid, myristic acid, palmitic acid and stearic acid was successfully prepared with the mass ratio of 61.09/24.61/8.13/4.01/2.16. Thereafter, the innovative Ag-coated polyurethane (PU) fibers membranes with different concentrations of Ag, which were selected as a supporting material to adsorb the CA-LA-MA-PA-SA eutectics, were successfully fabricated through electrospinning followed by magnetron sputter. The energy dispersive X-ray confirmed that Ag nanoclusters were successfully deposited on the surface of PU fibers as a result of sputter coating. The observations of atomic force microscope indicated that the surface roughness of the PU fibers significantly increased with increase in coating time. The scanning electron microscope images demonstrated that the CA-LA-MA-PA-SA eutectics were uniformly distributed into the three-dimensional porous structures of uncoated and Ag-coated PU fibers membranes. Furthermore, the differential scanning calorimeter curves suggested that the CA-LA-MA-PA-SA/PU/Ag composites phase change materials (PCMs) possessed melting enthalpies about 110 kJ/kg and melting temperature around 17 °C. The absorption ratios of the CA-LA-MA-PA-SA eutectic in composite PCMs was approximately at 73.74%–83.18%. The investigation on thermal performance indicated that we achieved higher melting and freezing rates of the CA-LA-MA-PA-SA/PU/Ag composites PCMs by increasing coating time. In addition to this, after depositing Ag nanoparticles the melting and freezing times of composites PCMs were shortened to about 21%–65%. [ABSTRACT FROM AUTHOR]

This paper demonstrated a novel magnetron sputtering method used for the improvement in thermal energy storage and retrieval rates of phase change materials (PCMs). The ten types of ternary fatty acid eutectics (i.e., CA-LA-MA, CA-LA-PA, CA-LA-SA, CA-MA-PA, CA-MA-SA, CA-PA-SA, LA-MA-PA, LA-MA-SA, LA-PA-SA and MA-PA-SA) were firstly prepared using five fatty acids such as capric acid (CA), lauric acid (LA), myristic acid (MA), palmitic acid (PA) and stearic acid (SA) and then selected as solid-liquid PCMs. Thereafter, magnetron sputter coating was used to deposit the functional silver (Ag) nanolayers onto the surface of electrospun polyacrylonitrile (PAN) nanofibrous mats serving as supporting skeleton. Finally, a series of composite PCMs were fabricated by adsorbing the prepared ternary eutectics into three-dimensional porous network structures of Ag-coated PAN membranes. The observations by EDX determined the formation of Ag nanolayers on the PAN nanofibers surface after magnetron sputtering. The SEM images illustrated that the Ag-coated PAN nanofibers appeared to have larger fiber diameter and rougher surface. Ag-coated PAN nanofibrous mats could effectively prevent the leakage of molten ternary eutectics and help maintain form-stable structure due to surface tension forces, capillary and nanoconfinement effects. The DSC results suggested that the phase change temperatures of the ternary fatty acid eutectics were obviously lower than those of individual fatty acids and their binary eutectics. The adsorption rates of ternary fatty acid eutectics in the composite PCMs were determined to be about 89-98 %. The thermal performance test indicated that the metallic coating of Ag dramatically improved the thermal energy storage and retrieval rates of the composite PCMs. [ABSTRACT FROM AUTHOR]

SUMMARY In this study, four fatty acids of lauric acid (LA), myristic acid (MA), palmitic acid (PA), and stearic acid (SA) were selected to prepare six binary fatty acid eutectics of LA-MA, LA-PA, LA-SA, MA-PA, MA-SA, and PA-SA; thereafter, electrospun ultrafine composite fibers with the binary fatty acid eutectics encapsulated in the supporting matrices of polyethylene terephthalate (PET) were prepared as innovative form-stable phase change materials for storage and retrieval of thermal energy. The morphological structures and thermal energy storage properties of the ultrafine composite fibers were characterized by scanning electron microscope (SEM) and differential scanning calorimeter (DSC), respectively. The SEM results indicated that the fibers had the cylindrical morphology with diameters of 1-2 µm; some had smooth surfaces, while others had wrinkled surfaces with grooves. The DSC results indicated that the phase transition temperatures of binary fatty acid eutectics were lower than those of individual fatty acids; the enthalpy values associated with melting and crystallization for the eutectics encapsulated in the composite fibers were considerably reduced, whereas there were no appreciable changes on the phase transition temperatures. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The ultrafine composite fibers based on the composites of binary fatty acid eutectics and polyethylene terephthalate (PET) with varied fatty acid eutectics/PET mass ratios (50/100, 70/100, 100/100 and 120/100) were fabricated using the technique of electrospinning as form-stable phase change materials (PCMs). The five binary fatty acid eutectics including LA–MA, LA–PA, MA–PA, MA–SA and PA–SA were prepared according to Schrader equation, and then were selected as an innovative type of solid–liquid PCMs. The results characterized by differential scanning calorimeter (DSC) indicated that the prepared binary fatty acid eutectics with low phase transition temperatures and high heat enthalpies for climatic requirements were more suitable for applications in building energy storage. The structural morphologies, thermal energy storage and thermal stability properties of the ultrafine composite fibers were investigated by scanning electron microscope (SEM), DSC and thermogravimetric analysis (TGA), respectively. SEM images revealed that the electrospun binary fatty acid eutectics/PET ultrafine composite fibers possessed the wrinkled surfaces morphologies compared with the neat PET fibers with cylindrical shape and smooth surfaces; the grooves or ridges on the corrugated surface of the ultrafine composite fibers became more and more prominent with increasing fatty acid eutectics amount in the composite fibers. The fibers with the low mass ratio maintained good structural morphologies while the quality became worse when the mass ratio is too high (more than 100/100). DSC measurements suggested that the heat enthalpies of melting and crystallization of the ultrafine composite fibers increased gradually with increasing fatty acid eutectics amounts, but their phase transition temperatures had almost no obvious variation as relative to the corresponding fatty acid eutectics. Meanwhile, the characteristic temperatures and heat enthalpies of the ultrafine composite fibers varied with the different types of binary fatty acid eutectics. TGA results indicated that the degradation of electrospun binary fatty acid eutectics/PET ultrafine composite fibers with representative mass ratio of 100/100 had two steps and corresponded respectively to the degradations of binary fatty acid eutectics and PET polymer chains; and the charred residue at 700°C of the composite fibers was lower than that of the neat PET fibers. It could be envisioned that the electrospun binary fatty acid eutectics/PET composite fibers would be extensively used for latent heat storage in the field of building energy conservation. [Copyright &y& Elsevier]

• Co-electrospinning method was used for regulating phase change temperature. • Fatty acid eutectic/PS/fatty acid eutectic form-stable PCCFMs were developed. • Melting peak temperatures were about 17–24 °C with the 1 °C temperature interval. • Phase change enthalpies of form-stable PCCFMs were approximately 41–60 kJkg−1. • The membranes were more suitable to use in thermo-regulating fibers and textiles. The seven kinds of fatty acid eutectics including capric-lauric acid (CL), capric-myristic acid (CM), capric-palmitic acid (CP), capric-stearic acid (CS), capric-lauric-myristic acid (CLM), capric-lauric-stearic acid (CLS) and capric-myristic-palmitic acid (CMP) were selected as solid-liquid PCMs. And then co-electrospinning method was used to produce and design innovative fatty acid binary eutectic/polystyrene/fatty acid binary eutectic (i.e., CL/PS/CL, CM/PS/CM, CP/PS/CP, CS/PS/CS, CL/PS/CM, CL/PS/CP, CL/PS/CS, CM/PS/CP, CM/PS/CS and CP/PS/CS) and fatty acid binary eutectic/polystyrene/fatty acid ternary eutectic (i.e., CL/PS/CLM, CM/PS/CLM, CP/PS/CLM, CS/PS/CLM, CL/PS/CLS, CM/PS/CLS, CP/PS/CLS, CS/PS/CLS, CL/PS/CMP, CM/PS/CMP, CP/PS/CMP and CS/PS/CMP) form-stable phase change composite fibrous membranes (PCCFMs) with the melting peak temperatures ranging from about 17 to 24 °C with the temperature interval of 1 °C. The scanning electron microscope images revealed that these electrospun PS-based form-stable PCCFMs exhibited well and stable nanofibrous network structure. The differential scanning calorimetry results indicated that the phase change temperatures of electrospun PS-based form-stable PCCFMs could be regulated to the lower temperature range by changing the type of the loaded fatty acid binary and ternary eutectics, and their phase change enthalpies were approximately 41–60 kJ/kg. Based on the consideration of phase change temperatures, the developed electrospun PS-based form-stable PCCFMs could be more suitable to use in temperature-regulated fibers and textiles as well as energy efficiency building applications. [ABSTRACT FROM AUTHOR]