Microencapsulation of a PCM through membrane emulsification and nanocompression-based determination of microcapsule strength

Abstract

Microencapsulating a phase-change material (PCM) has become a prominent method of creating a stable environment in which the PCM can undergo its phase change without affecting the environment in which it is used. The method of encapsulation used in this study takes advantage of a new technology known as membrane emulsification and suspension polymerization. This study investigates the encapsulation of the paraffin wax RT21Ò in a poly(methyl methacrylate) shell, which could be used to increase the thermal mass of a building. The objectives of the study are: (1) to encapsulate RT21Ò through the use of membrane emulsification and (2) to test the mechanical properties of the microcapsules under nanocompression. Membrane emulsification was carried out using Shirasu porous glass hydrophilic membranes of pore sizes 10, 10.2, and 20 lm. Polymerization was conducted in a batch reactor with methyl methacrylate as the monomer in the temperature range 70-90°C. The thermal properties (the latent heat of melting and melting temperature) of the microcapsules were tested using a differential scanning calorimeter. Particle size analysis was conducted to determine the average size distribution of the microcapsules produced. Membranes with pore sizes of 10, 10.2, and 20 lm produced microcapsules with average diameters of 22.40 ± 1.47, 25.38 ± 0.80, and 37.50 ± 1.69 lm, and average latent heats of 113.91 ± 12, 116.69 ± 1.40, and 109.89 ± 8.69 J/g, respectively. In order to determine the mechanical properties of these microcapsules, a modified nanoindentation compression technique was used to test the bursting force for individual microcapsules.

Kaolinite stabilized paraffin composite phase change materials for thermal energy storage

“…Inorganic PCM include crystalline hydrous salts, molten salts, metals, and alloys, while organic PCM are usually paraffins and fatty acids (Li and Wu, 2012). Commercial paraffin and fatty acid have many advantages, such as low price, high storage density, wide melting range, chemical inertness, and lack of corrosiveness and supercooling (Rozanna et al, 2005;Sharma et al, 2009;Rahman et al, 2012;Sarier and Onder, 2012). Nevertheless, these organic PCM still have some disadvantages, including leakage in the molten state and lower thermal conductivity (λ, around 0.2 W·m − 1 ·K −1 ), which restricts their wide application (Arteconi et al, 2012;Li et al, 2013a).…”

Paraffin as Phase Change Material

“…As a result, paraffin has been encapsulated by PVA modified polymethyl methacrylate (PMMA). Adding this modifier forms a smooth surface of the microencapsulates [36,37].…”

Structured microparticles with tailored properties produced by membrane emulsification

“…The prepared particles were investigated as potential candidates for encapsulation of phase change materials (Chaiyasat et al, 2009;Rahman et al, 2012) and self-healing agents (Liu et al, 2011). A liquid encapsulated within the shell can be evaporated or extracted to produce hollow polymer capsules providing excellent light scattering and thermal insulation properties that can be used as coatings, pigments, floating drug delivery systems, and catalyst supports (Liu et al, 2010).…”