Thermal behavior of flexible and breathable sandwich fibrous polyethylene glycol (PEG) encapsulations

Textiles incorporating phase change material have attracted increasing attention due to their temperature regulating function. Although a great progress has been made in the development of phase change material textiles, it has been found that the loading amount of phase change materials is limited by other final properties. Recently, we have proposed a sandwich fibrous phase change material encapsulation with a relatively high phase change material loading amount, which is a multi-layer fabric structure containing phase change material. However, the breathability of sandwich fibrous phase change material encapsulation should be improved because there is no path for air to penetrate through. In this work, the sandwich fibrous phase change material encapsulation structure with polyethylene glycol as phase change material is modified by introducing different air pockets in the thermal function layer ranging from 19% to 64%. The leakage phenomenon, phase transition behavior, thermal energy storage, breathability, T-history and practicality of the breathable sandwich fibrous phase change material encapsulations are investigated. As a result, the maximum polyethylene glycol loading amount of the phase change materials pocket is 83 wt%, and there is no leakage of polyethylene glycol during working time. The overall enthalpy value of the breathable sandwich fibrous phase change material encapsulation ranges from 27 J/g to 48 J/g. The optimal air permeability and water vapor resistance of the breathable sandwich fibrous phase change material encapsulation is 9 mm/s under 100 Pa and 34.5 m ² Pa W ⁻¹ . Furthermore, the heterogeneous heat transfer through the breathable sandwich fibrous phase change material encapsulation is found due to the complicated thermal resistances of the hybrid thermal functional layer. In addition, for breathable sandwich fibrous phase change material encapsulation, the flexibility, hydrophobicity, self-cleaning property, abrasion resistance, and stability after water immersion are found. We believe the research has a great potential in various applications related to phase change material.