Titanyl sulfate-based TiO2-paraffin phase change microcapsules: Evaluation of alkyltriethoxysilane modification and thermoregulation applications

Abstract

Titanium dioxide (TiO2) phase change microcapsules show promising applications in building temperature regulation and heat transfer due to their high thermal reflectivity and high thermal conductivity. Currently, the preparation of TiO2 microcapsules predominantly relies on expensive and highly toxic titanate as a raw material. In this study, a new type of TiO2-paraffin phase change microcapsules was prepared by chemical precipitation method using cheap and low toxic titanium sulfate dihydrate (TSD) as titanium source and alkyltriethoxysilane as modifier. The results showed that when methyltriethoxysilane was used as a modifier and the dosage was 1/3 of TSD, the core-wall ratio was 1:1, and the reaction temperature was 65 °C, the performance of the modified TiO2 phase change microcapsules was the best. The melting enthalpy was 112.8 J/g, the core material content reached 83.70 %, which was 48.06 % higher than that of the unmodified microcapsules, and the melting permeability ratio was 12.88 %. The test chamber containing the sample TiO2 phase change microcapsules underwent a temperature rise-cooling test, transitioning from 25 ℃ to 65 ℃ under simulated solar light conditions. The heating time for the phase change microcapsules with modified TiO2 was 28 % faster compared to those containing unmodified TiO2, while the cooling time was 13.00 % slower. It is shown that the light conversion, as well as the thermal storage capacity of TiO2 phase change microcapsules, are significantly improved after organosilicon modification.