Fatty boron ethers as new organic solid-liquid phase change materials: tridodecylborate, tritetradecylborate and trioctadecylborate

• Published in: Energy sources. Part A, Recovery, utilization, and environmental effects Vol. 45; no. 2; pp. 6248 - 6261
• Main Authors: Paçacı, Timur, Alkan, Cemil
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01.06.2023
• Subjects: boron ethers; fatty alcohol; Phase change materials; thermal conductivity; thermal property
• ISSN: 1556-7036; 1556-7230
• DOI: 10.1080/15567036.2023.2213664

Tridodecylborate (TD), tritetradecylborate (TT) and trioctadecylborate (TO) were produced as solid-liquid phase change materials (SL-PCMs) for thermal energy storage (TES) applications via condensation of boric acid and 1-dodecanol, 1-tetradecanol, and 1-octadecanol, respectively. Boron is used for the first time in the production of such synthetic PCMs instead of carbonaceous compounds. Produced fatty boron ether compounds were structurally characterized by using FT-IR and proton and carbon NMR spectroscopy methods as they were thermally characterized by DSC and time/temperature analysis techniques. Melting points of TD, TT, and TO are in the range of 10.1-10.8, 26.9-27.0, and 50.8-51.8°C in the thermal cycling tests, respectively, while solid-liquid phase change melting/crystallization enthalpies of them are 110.4/-112.8, 125.7/-132.3, and 141.8/-149.9 Jg-1, respectively. That is, the produced fatty boron-ethers had different operating temperatures than the fatty alcohols from which they were produced and could produce significant enthalpy values for heat energy storage applications. The increase in chain length caused an increase in enthalpy values as in fatty alcohols. The lack of PCM with similar melting and enthalpy values expands the usage area of synthesized boron-ethers. The thermal stability of fatty boron ether compounds (TD, TT, and TO) were tested by 10 times repeated DSC measurements instead of accelerated thermal cycling and FTIR spectroscopy analysis after these operations. In the surface examinations of boron ethers, original crystal formation was observed, and the loss of appearance above the phase transition temperature indicated amorphous transformation. In addition, it has been proven in the TG investigations that the fatty boron ethers produced can remain intact up to higher temperatures than fatty alcohols.