Production of multifunctional bamboo-based phase change encapsulating material by straightforward dry ball milling

Phase change materials (PCMs) have attracted much attention due to their high energy storage density and thermal efficiency. In this paper, bio-based bamboo flour (BF) and polyethylene glycol (PEG) were compounded together as a shape stable phase change material (SSPCM). A novel bamboo-based matrix for packaging organic PCMs was prepared by a simple dry ball milling process. Using the reinforcement of bamboo fiber and the porous characteristics of parenchyma cells, PEG / BF not only has high encapsulation rate, but also has high thermal conductivity. The leakage test results showed that the BF adsorption capacity with longer milling time was improved. The packaging ability of BF on PEG tended to be unchanged after 12 h of milling. The maximum loading of both PEG 4000 and 2000 in SSPCMs was 50 wt%, while PEG 10,000 was 70 wt%. The composites had good shape stability and no leakage defects. FTIR results showed that there was no new diffraction peak in composites appeared indicating that limited chemical reaction happened between BF and PEG. The results of XRD showed that the crystallinity of PEG decreased with the employ of BF. The phase transition temperature of SSPCMs measured by DSC did not depend on the content of BF. The highest melting latent heat of SSPCM was 113 J/g by PEG 10,000/30% BF and the enthalpy efficiency reached 61.08%. Continuous network structure of bamboo fiber in composites improved the thermal conductivity of the PEG/BF. The highest thermal conductivity of PEG 10,000/BF products can reach 0.64 W/m•K. The results of thermal cycle tests and TG also showed that PEG/BF had good thermal and chemical stability. The study proved that the composite had potential application value in solar energy storage combined with other materials such as polymer bamboo composites, bamboo based composites and other bamboo fiber reinforced materials.