Didodecyl terephthalate, ditetradecyl terephthalate, and dioctadecyl terephthalate compounds as novel phase change materials for medium temperature applications

Abstract

Some of the fatty alcohols; 1-dodecanol, 1-tetradecanol and 1-octadecanol reacted to terephthaloyl chloride to produce some novel solid-liquid phase change materials (PCMs). It resulted in stable fatty esters for use as PCMs at considerably higher temperatures. Acyl chloride of terephthalic acid and one of the fatty alcohols reacted at 80 °C. Fourier transform infrared (FT-IR) spectroscopy with an attenuated total reflection accessory and 1H nuclear magnetic resonance (1H NMR) spectroscopy was exploited for structural characterization. Surface morphology of the produced materials was investigated through polarised optical microscopy (POM). Thermal properties were determined by a differential scanning calorimeter (DSC) as thermal endurance limits were determined by a thermogravimetric analyser (TGA). Thermal energy storage (TES) properties like melting-crystallisation temperatures and latent heats were found in the range of 66.0–81.0 °C and 179.2–191.2 J/g respectively by using a DSC instrument. The results revealed that the Didodecyl terephthalate (DDDT), ditetradecyl terephthalate (DTDT) and dioctadecyl terephthalate (DODT) as PCMs were thermally reliable with respect to 1000 times accelerated thermal cycling. According to physicochemical properties, the produced materials are valuable for use at considerably high temperatures as organic PCMs, which was surprising as there are very little organic alternatives for those temperatures.