Microencapsulation in Thermo-regulating Fabric: An Overview

Microencapsulation technology was utilized in the early 1980s by the United State National Aeronautics and Space Administration (NASA) with the aim of managing the thermal barrier properties of space suits. The microcapsules have walls less than 1 μm thick and are typically 20 - 40 μm in diameter, with a Phase Change Material (PCM) loading of 80% - 85%. These containers release their core contents under controlled conditions to suit a specific purpose. The microcapsules are produced by depositing a thin polymer coating on small solid particles or liquid droplets, or on dispersions of solids in liquids. The small capsule size provides a relatively large surface area for heat transfer. The rate at which the PCM reacts to an external temperature change is very rapid. PCM microcapsules are being used to develop textile materials with higher thermal mass and PCM slurries with high heat storage and transfer properties. In this paper, Melamine–formaldehyde microcapsules containing eicosane were prepared by in situ polymerization. Knit fabrics made of polyester, were treated with phase change-material microcapsules by a pad–dry–cure method with a polyurethane binder. The treated fabrics were evaluated in terms of the thermal properties, moisture vapor permeability, moisture regain, air permeability, with respect to the add-on of microcapsules. The morphology and laundering properties of the treated fabrics were also evaluated.