Abstract: Expanded graphite(EG) and polyethylene glycol(PEG) were chose as a matrix and phase change material ,PEG/EG /polypropylene(PP) composite phase change thermal energy storage material was prepared to utilize the characteristic that EG can adsorb PEG well.The structure , morphology, and thermaI properties of composite phase change material were then characterized by means of FT-IR,SEM and DSC.It is shown that PEG can be uniformIy absorbed into the pore network of EG，that EG remains its vermiform structure in PCMs. Because of the effect of capillary force and surface tension force, polyethylene glycol was very difficult to leak out from the porous during solid-liquid phase change happened. The good rheological,morphological and thermal properties obtained when the ratio of PEG/EG/PP was 73.2/1.8/25.

Key words: polyethylene glycol, expanded graphite, polypropyoene, phase-change material