Composite phase change materials prepared by encapsuling paraffin in PVC macrocapsules

• PVC macrocapsules coated with SiO2 were synthesized.
• Paraffin was encapsuled in the capsules.
• The composite PCM has high heat capacity.
• The composite PCM has no surpercooling.

A novel phase change material capsules with SiO2 in their surface was prepared by absorbing paraffin into PVC hollow capsules and by the polycondensation reaction of TEOS in different conditions. X-ray photoelectron spectroscopy (XPS) analysis and scanning electronic microscope (SEM) were used to determine chemical composition and microstructure of the composite capsules, respectively. Enthalpy capacity and thermal stability of the composite capsules are systematically characterized by using differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA) and thermocycling tests. The composite has high heat capacity with good stability and absence of supercooling phenomena.