Carbonized bamboo parenchyma cells loaded with functional carbon nanotubes for preparation composite phase change materials with superior thermal conductivity and photo-thermal conversion efficiency

Phase change materials (PCMs) are widely used in the field of energy storage management owing to their store and release thermal energy ability through latent heat. However, organic PCMs have the problems of easy leakage, low thermal conductivity and photo-thermal conversion performance, which greatly prevent their practical application. In order to solve these defects, a novel shape stable composite PCMs was prepared by adding polyethylene glycol (PEG) into porous carbonized bamboo parenchyma cells (CPC) containing carbon nanotubes (CNTs). The supporting materials containing CNTs not only had unique three-dimensional porous structure, but also had continuous heat transfer network structure. Compared with pure PEG, the thermal conductivity (TC) of PEG/CPC-CNTs with 0.494 W/m.K was increased by 128%. The prepared composite PCMs had melting and crystallization latent heat with 149.4 J/g and 144.1 J/g. In terms of shape stability, the PEG encapsulation rate by CPC reached 80% which was better than that of untreated PC. Thermo-gravimetric (TG) analysis and thermal cycling experiments showed that PEG/CPC-CNTs had superior physical and chemical stability. More importantly, the matrix material composed of CPC and CNTs made the composite PCMs with a photo-thermal conversion efficiency up to 87.2%. So, PEG/CPC-CNTs composite PCMs with a simple preparation method have great application potential in the field of bamboo or wood based buildings materials such as wood plastic composite, particleboard, floor or roof panels and so on.