Search

In this study, caprylic (octanoic) acid microcapsules were synthesized with polystyrene shell material using the emulsion polymerization method. The influence of the type and concentration of the cross linking agent on the phase-change properties of the microcapsules was examined. The structure and properties of the microcapsules have been characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). A second main contribution of this work is to investigate whether we could synthesize microcapsules with the same thermal properties during serial production. The effects of serial production on microencapsulated caprylic acid (microPCMs) have been investigated by thermal methods. The results show that reproducibility is an important parameter in the microencapsulation process. It was determined that when the synthesis amount is increased, we obtained lower efficiency in the microencapsulation of caprylic acid. (C) 2016 Elsevier B.V. All rights reserved.

Paraffin is a common phase-change-material (PCM) exploited in many thermal and solar energy storage applications. Its relatively large latent heat with a stable phase change, nontoxicity and noncorrosivity are the main reasons. Paraffin's low thermal conductivity may become a drawback for high power applications. In this study, the effect of adding nanomaterials to enhance paraffin's thermal performance is investigated. Nanomagnetite (Fe3O4) particles were prepared by sol-gel method for this investigation. Once characterization of nanomagnetite was done, it was added at 1%, 5%, 10%, and 15% ratios to paraffin (melting range: 46-48 degrees C) to obtain a paraffin nanocomposite. Thermal characterization with Differential Scanning Calorimeter (DSC) shows that the latent heat storage capacity of paraffin has been increased for 10% nanomagnetite composite, while the melting temperature range remained the same. (C) 2014 Elsevier B.V. All rights reserved.

WOS: 000354740300007, After cellulose, chitosan is the second-most-abundant natural resource and can be used as shell material during microencapsulation. In this study, chitosan-gelatin (CG) microcapsules and microcomposites containing either caprylic or decanoic acid were prepared according to the complex coacervation method and cross-linked by glutaraldehyde. To study the influence of the glutaraldehyde mass ratio upon encapsulation, as well as both the physical and thermal properties of the resulting microcapsules, the properties of microencapsulated phase-change materials (microPCMs) were analyzed by using scanning electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Results show the successful synthesis of microPCMs and melting temperatures of approximately 11.5 and 24.2 degrees C with latent heat storage capacities of 79 and 73Jg(-1) for microPCMs containing caprylic acid and those containing decanoic acid, respectively., Scientific and Technological Research Council of Turkey (TUBITAK) [111M614], The authors thank the Scientific and Technological Research Council of Turkey (TUBITAK) (project code: 111M614) for its financial support of this study.

WOS: 000356122500030, In this work, we synthesized a series of four nanocapsules containing n-alkanes (CnH2n+2), namely tetradecane, pentadecane, hexadecane, and heptadecane, in poly(styrene-co-ethylacrylate) using an emulsion copolymerization method. The nanocapsules were characterized according to their geometric profiles, phase transition temperatures, phase transition heats, mean particle sizes, and chemical stabilities by means of scanning electron microscopy, differential scanning calorimetry, thermal gravimetric analysis and Fourier transform infrared spectroscopy. Furthermore, we also focused on the effect of the core/shell mass ratio on the phase change properties of the nanocapsules. We found that microcapsules were synthesized successfully and that the best core/shell mass ratio was 3:1 for this study. These results indicate that encapsulated n-alkanes with poly(styrene-co-ethylacrylate) have an excellent potential for energy storage. (C) 2014 Elsevier Ltd. All rights reserved., Scientic & Technical Research Council of Turkey (TUBITAK) [TUBITAK 111M614], We would like to thank The Scientic & Technical Research Council of Turkey (TUBITAK) (The Project Code: TUBITAK 111M614) for their financial support for this study. And also we would like to thank Mr. Suleyman Konuklu for his technical support for this study. Finally, we would like to extend special thanks to the editor and the anonymous reviewers for their constructive comments and suggestions in improving the quality of this paper.

WOS: 000329595800012, In this study, caprylic acid (octanoic acid) suitable for thermal energy storage applications was microencapsulated with different wall materials, including urea-formaldehyde resin, melamine-formaldehyde resin, urea+melamine-formaldehyde resin. Microcapsules were prepared using coacervation method. Hardening process of microencapsulated phase change material (PCM) was done with formaldehyde. The morphology and particle sizes of microencapsulated PCM were analyzed by scanning electron microscopy, (SEM). The latent heat storage capacities of caprylic acid and microencapsulated caprylic acid were determined with differential scanning calorimetry (DSC). The chemical characterization of microcapsules was determined by Fourier transformed infrared (FTIR) spectroscopy. It is concluded that urea-formaldehyde resin was the best capsule wall material for caprylic acid. Based on all results, it can be considered that the microcapsules were synthesized successfully and that, the phase change enthalpies of melting and freezing were about 93.9 J/g and 106.1 J/g, respectively, the particle diameter was 200 nm-1.5 mu m. (C) 2013 Elsevier B.V. All rights reserved., Scientific & Technical Research Council of Turkey (TUBITAK) [TUBITAK 111M614]; Research Projects Unit of Nigde University [FEB2011118], We would like to thank The Scientific & Technical Research Council of Turkey (TUBITAK) (The Project Code: TUBITAK 111M614) and Research Projects Unit of Nigde University (The Project code: FEB2011118) for their financial support for this study. And also we would like to thank Mr. Suleyman Konuklu for his technical support for this study.

WOS: 000334897700039, The main purpose of this study is to obtain leakage-free, thermally stable decanoic acid microcapsules (microPCMs) for thermal energy storage applications. Decanoic acid (capric acid) is an environmentally friendly fatty acid since it is obtained from vegetable and animal oils. MicroPCMs were prepared with different capsule wall materials via a one-step in situ polymerization technique. The properties of microencapsulated PCMs have been analyzed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analyzer (TGA), Fourier transform infrared (FTIR) spectra analysis and particle size analyzer. The microPCMs prepared using Poly(urea-formaldehyde) (PUF) exhibit higher heat capacities and the microPCMs prepared using Poly(melamine-formaldehyde) (PMF) exhibit higher thermal stabilities. In order to obtain microPCMs with better properties such as suitable latent heat and better heat resistance at high temperatures, we microencapsulated decanoic acid with Poly (melamine-urea-formaldehyde) (PMUF). Furthermore, the effects of surfactants on microPCMs with PMUF were investigated by SEM, a particle size analyzer, DSC, and TGA. The results show that the binary surfactant system was a suitable emulsifier for this process. We determined that the melting temperature was close to 33 degrees C, the latent heat storage capacity was about 88 J/g, and the mean particle diameter was 0.28 mu m for microPCMs with PMUF. We recommend decanoic acid microencapsulated with PMUF for thermally stable and leakage-free applications above 95 degrees C. (C) 2014 Elsevier Ltd. All rights reserved., Scientific & Technical Research Council of Turkey (TUBITAK) [TUBITAK 111M614]; Research Projects Unit of Nigde University [FEB2011/18], We would like to thank The Scientific & Technical Research Council of Turkey (TUBITAK) (The Project Code: TUBITAK 111M614) and Research Projects Unit of Nigde University (The Project Code: FEB2011/18) for their financial support for this study. We also would like to thank the editorial board and the anonymous reviewers for their helpful and constructive comments and suggestions thatgreatly contributed to improve the quality of the paper.