One-step fabrication of fatty acids/nano copper/polyester shape-stable composite phase change material for thermal energy management and storage

In this contribution, for the first time, fatty acids/nano copper/polyester composites were prepared by a facile and one-step route through simultaneous in situ formation of copper nanoparticles and direct absorption of fatty acids to polyester fibers for thermal energy management and thermal conductivity improvement. This eliminates synthesis of copper particles in the separate processing and also other processing such as electrospinning of fibers with using solvents and micro and nano encapsulation as well as shortening the time and processing steps. Two eutectics of fatty acids including myristic/lauric acid and myristic/stearic acid were used as phase change materials, ascorbic acid as a clean reducing agent for in situ synthesis of copper nanoparticles and polyester fibers as supporting material. The thermal behavior of the samples was investigated by using differential scanning calorimetry and thermogravimetric analysis. Based on experimental results, the prepared composites provided a proper and wide temperature range of phase transitions from 29.4-34.2 to 35.7-52.7 degrees C with corresponding enthalpies of 40.3-53.9 and 41.9-55.0 J/g, respectively, that is appropriate for using in diverse applications. The incorporation of copper nanoparticles into eutectic of phase change materials leads to a 77.5% increase in thermal conductivity for the sample treated with lowest copper content. In addition, the treated samples indicated good thermal stability and reliability even after 100 melting and solidifying cycles. Finally, the mentioned method can be utilized for producing shape-stable composite phase change material with appropriate phase transition ranges for low temperature energy storage/retrieval systems.