Preparation and characterization of a series of thiourea derivatives as phase change materials for thermal energy storage

摘要

A series of solid-liquid phase change materials, thioureaderivatives, were prepared via condensation of thiourea with therespective carboxyl chlorides (lauroyl chloride, myristoyl chloride,and palmitoyl chloride) and were then characterized by using FT-IR,^1H-NMR, differential scanning calorimetry (DSC), andthermogravimetric (TG) analysis. The thiourea derivatives(1,3-didodecanoyl thiourea, 1,3-ditetradecanoyl thiourea, and1,3-dihexadecanoyl thiourea) were structurally symmetric and had longalkyl groups to crystallize. Thermal analysis by DSC andspectroscopic investigation by FT-IR spectroscopy were performed onthe samples before and after thermal cycling tests to determinethermal reliability. The maximum latent heats of melting and freezingof the thiourea derivatives were found to be 114.6 and --110.0 J/g for1,3-didodecanoyl thiourea, 119.5 and --122.4 J/g for1,3-ditetradecanoyl thiourea, and 148.8 and --142.7 J/g for1,3-dihexadecanoyl thiourea after accelerated thermal cycling. A TGinstrument was used to determine the starting point of degradation inthe thiourea derivatives; it was found that the thiourea derivativesdegraded at sufficiently higher temperatures than the expected utilitytemperatures.