Surface Adsorption in PEG/Hydroxyapatite and PEG/Dickite Composite Phase Change Materials

摘要

The traditional view is that the pore structure of substrate determines the encapsulation ratio. The work proposed that surface adsorption was also a cause in this method. Polyethylene glycol/hydroxyapatite (PEG/HAP) and polyethylene glycol/dickite (PEG/D) were prepared by encapsulating polyethylene glycol (PEG) with hydroxyapatite (HAP) and dickite as substrates. The pore structures of HAP and dickite were characterized by BET and mercury intrusion porosimetry, respectively. Through SEM, XPS, FT-IR, and XRD, the process of PEG being encapsulated by the two materials was studied. The leakage cycle test was performed on PEG/HAP. The experiments proved that HAP adsorbed PEG through the surface and the surface adsorption played an essential role in the direct impregnation process. According to the distribution of PEG among HAP particles and the adsorption mechanism of HAP, a model was created to describe the encapsulation ratio in the direct impregnation process. The maximum encapsulation ratio of PEG/HAP calculated by this model is 75.98%, which is close to the actual value (74.66%).