Form-stable phase change materials based on castor oil and palmitic acid for renewable thermal energy storage

Utilization of renewable biomass to prepare phase change material (PCM) that can reversibly store renewable thermal energy is of great interest. Castor oil with functional hydroxyl groups is especially attractive for the preparation of polymeric materials. In this work, a novel castor oil-based polyurethane-acrylate oligomer (COPUA) was firstly synthesized through a two-step condensation reaction. Followed by in situ polymerization of COPUA in the presence of palmitic acid (PA), a novel biomass-based form-stable PCM was prepared, in which renewable PA serves as phase change functional ingredient and castor oil-based crosslinking network acts as encapsulation material. Tailoring the mass ratio of PA and COPUA provides the ultimate encapsulation ratio (70%) of PA in form-stable PCM. The chemical structure, crystalline property, thermal property of form-stable PCM were characterized using Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, differential scanning calorimetry and thermogravimetric. Those results demonstrate that the prepared form-stable PCM possesses that good thermal storage capacity with the phase change enthalpy reaches 141.2 J g −1 . Accelerated thermal cycling test was also performed to illustrate the thermal reliability of form-stable PCM.