Preparation of Melamine - Formaldehyde Microcapsules Containing Hexadecane as a Phase Change Material: The Effect of Surfactants Type and Concentration

Microcapsules containing n-hexadecane (HD) as the core and melamineformaldehyde (MF) prepolymer as the shell were prepared by in-situ dispersion polymerization. The effects of surfactants type and amount were studied in relation to the morphology and thermal properties of microcapsules. The morphology of the microcapsules was studied using scanning electron microscopy (SEM) and thermal properties were detected by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). SEM images showed that the increase in the amount of Triton X-100 (non-ionic) to SDS (ionic) ratio resulted in the agglomeration of the prepared microcapsules. This increase led also to lower encapsulated hexadecane and thermal stability of microcapsules. As a result, the optimum composition of the above surfactants for obtaining higher thermal stability and proper morphology wasfound to be 20 wt% of Triton X-100 and 80 wt% of SDS in the recipe. The optimum total amounts of surfactants was 4 wt%, which resulted in spherical and separate microcapsules. DSC and TGA analyses revealed that a sample prepared with 4 wt% of surfactants was not only successful in encapsulation of hexadecane but also showedhigher thermal stability compared with other formulations.