Effect of pH Value on the Structure and Properties of n-Eicosane@Melamine Urea-Formaldehyde Phase Change Microcapsules

Abstract

In this article, n-eicosane@MUF phase change microcapsules were prepared by in-situ polymerization with n-eicosane as the core material and melamine urea-formaldehyde (MUF) resin as the shell material. The effects of pH values from 3.5 to 6.0 on the surface morphology, particle size distribution, latent heat of phase transformation, encapsulation degree, thermal stability, and permeability resistance of the microcapsules were investigated. The results showed that the surfaces of the microcapsules gradually became smooth with the increase of pH value, and their encapsulation degree and impermeability also increased roughly. When the pH = 5.5, the particle size of the microcapsule samples ranged from 1.5 to 9.7 μm, the melting enthalpy was 178.8 J/g, and the encapsulation degree was 86.6%, which had the best thermal stability and impermeability. However, when the pH = 6.0, the phenomenon of microcapsule shell rupture occurred and the above performance no longer occurred.