Influences of PVA modification on performance of microencapsulated reversible thermochromic phase change materials for energy storage application

The aim of the paper was to enhance the mechanical properties and anti-permeability performance of microcapsules through shell modification to keep complete and stable structure during the manufacturing process. The effect of PVA adding dosage, modified methods and types of PVA on the performance of microcapsules was discussed in detail. When the PVA/MF ratio (0.04-0.25) was appropriate, the supercooling degree of microcapsules was reduced and thermal stability was improved to some extent. Furthermore, the modified method of adding PVA-1788 into microcapsules after curing probably formed the second protective encapsulation for RTPCMs, which contributed to obtaining MicroRTPCMs-2 with excellent mechanical properties and anti-permeability performance. Compared among the effects of various types of PVA modification on the performance of MicroRTPCMs, PVA with larger polymerization degree and higher alcoholysis degree can form modified resin with larger crosslinking degree, which was beneficial to generating more stable composite shell structure. Therefore, MicroRTPCMs1-2699 presented more outstanding mechanical properties and anti-permeability performance, satisfactory cycle stability and long-term reliability, as well as reversible thermochromic coloration and leakage-prevention performance. In the end, the main characteristic of RTPCMs was to in-situ observe the heat absorption, energy storage and heat release process of PCM cores, which would be great significance for the practical application of MicroRTPCMs in the fields of thermoregulated fibers, thermal energy storage textiles, heat energy transfers and energy-saving building materials.