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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]

Highlights • The Ag nanoparticles were used for improvement of heat transfer rates of PCCFMs. • The electrospun PAN/Ag-NPs fibrous membranes were selected as supporting materials. • The form-stable PCCFMs exhibited high phase change enthalpies about 138.1–156.7 kJkg−1. • The form-stable PCCFMs possessed suitable melting peak temperatures of about 24–30 °C. • The heat transfer rates were significantly improved due to the addition of Ag- NPs. Abstract Electrospun polyacrylonitrile/sliver nanoparticles (PAN/Ag-NPs) nanofibrous membranes were fabricated as supporting materials by direct dispersing Ag-NPs additives into PAN solutions. And then a series of form-stable phase change composite fibrous membranes (PCCFMs) were developed by physical adsorbing three different kinds of solid-liquid phase change materials (PCMs) with the melting temperatures of about 20–33 °C including butyl stearate (BS), capric-myristic acid binary eutectic (CA-MA), capric- palmitic-stearic acid ternary eutectic (CA-PA-SA) into electrospun PAN/Ag-NPs supporting membranes. The morphology and thermal properties were characterized by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter and measurement of melting and freezing times, respectively. DSC curves suggested that melting peak temperatures and enthalpies of the PAN/Ag-NPs-based form- stable PCCFMs were in the range of about 23.47–29.31 °C and 138.1–156.7 kJkg−1, respectively. Melting/freezing times were significantly shorten by about 29%/32% and 44%/52% for the BS/PAN/Ag-NPs5 and BS/PAN/Ag-NPs10 form-stable PCCFMs owing to the addition of Ag- NPs. [ABSTRACT FROM AUTHOR]

Highlights • The nano-graphite powder was used for improvement of heat transfer rates of PCCFMs. • The electrospun PAN/NG fibrous membranes were selected as supporting materials. • The form-stable PCCFMs possessed high phase change enthalpies about 120–139 kJ/kg. • The form-stable PCCFMs exhibited suitable melting temperatures of around 20–25 °C. • The melting and freezing times were significantly shortened due to the addition of NG. Abstract A series of electrospun polyacrylonitrile/nano-graphite (PAN/NG) composite fibrous membranes containing 0, 5 wt%, 10 wt%, 30 wt% and 50 wt% of NG additive were successfully fabricated as supporting materials, and then their mechanical properties and thermal stability were characterized by mechanical testing and thermogravimetric analyses. The five kinds of fatty acid ternary eutectics (i.e., CA-LA-PA, CA-LA-SA, CA-MA-PA, CA-MA-SA and CA-PA-SA) with the melting peak temperatures of around 20–25 °C were used as phase change materials to develop the novel ternary eutectic/PAN/NG form-stable phase change composite fibrous membranes (PCCFMs) through physical adsorption method. Scanning electron microscopy, differential scanning calorimetry and thermal performance test were employed to investigate the morphological structure and thermal performances of the developed form-stable PCCFMs. The results indicated that the NG additive not only enhanced the mechanical properties of composite fibrous membranes, but also effectively improved their thermal stability when the weight percentage of the loaded NG in the membranes was controlled in the 10 wt%. The SEM images revealed that the different types of ternary eutectic could be uniformly dispersed into the three-dimensional porous network structure of electrospun PAN/NG fibrous membranes. The DSC analysis indicated that the presence of NG additive had no significant influence on the phase change temperatures and enthalpies of the ternary eutectic/PAN/NG form-stable PCCFMs. These membranes possessed high phase change enthalpies of about 120–139 kJ/kg and an applicable melting peak temperature range of around 20–25 °C. The thermal performance tests suggested that the required melting and freezing times of form-stable PCCFMs were obviously shortened due to the formation of the efficient three-dimensional thermally conductive networks comprised of the NG molecular chains. [ABSTRACT FROM AUTHOR]

Five kinds of pure fatty acids such as capric acid (CA), lauric acid (LA), myristic acid (MA), palmitic acid (PA) and stearic acid (SA) were selected to prepare quaternary eutectics of CA-LA-MA-PA, CA-LA-MA-SA, CA-LA-PA-SA, CA-MA-PA-SA and LA-MA-PA-SA as novel solid-liquid PCMs. Ag-coated electrospun polyurethane (PU) fibrous membranes selecting as supporting materials were then fabricated by depositing Ag nanoparticles on the surface of electrospun PU fibers through magnetron sputtering. Thereafter, a series of innovative form-stable PCMs based on the composites of Ag-coated PU fibrous membranes and quaternary eutectics were successfully prepared by physical absorption. Energy-dispersive X-ray analysis demonstrated that the Ag nanolayers were uniformly covered on the surface of PU fibers. Fourier transform infrared spectroscopy spectra suggested that there was no chemical reaction between quaternary eutectics and Ag-coated PU fibrous membranes. Scanning electron microscope images revealed that quaternary eutectics were adsorbed and encapsulated into three-dimensional porous network structures of Ag-coated PU fibrous membranes after physical absorption. Differential scanning calorimetry curves indicated that quaternary eutectics exhibited lower phase change temperatures compared with those of individual fatty acids and binary eutectics. Onset melting temperatures and enthalpies of Ag-coated composite fibrous membranes were in the range of about 14-29 °C and 95-118 kJ kg, respectively. These composite fibrous membranes had good thermal reliability, and their adsorption capabilities were around at 71-91%. Thermal performance tests showed that the quaternary eutectics/PU/Ag composite fibrous membranes processed higher heat transfer efficiency owing to the incorporation of the Ag nanolayers with excellent thermal conductivity. [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]

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]