Microencapsulation of phase change material in water dispersible polymeric particles for thermoregulating rubber composites—A holistic approach

Abstract

Summary Summary To avoid the leakage of phase change materials (PCM) to its surrounding, microencapsulation of PCM in a polymeric shell is highly desirable. These microcapsules ideally should provide a platform to store and release latent heat of the PCM without undergoing any physicochemical transformation of core (PCM) as well as shell (polymer) materials. Several characteristics such as heat transfer efficiency, thermal conductivity, water dispersibility, and durability of the PCM capsules are dependent on the nature of shell materials. In the present study, a random copolymer of poly (methyl methcrylate‐co‐2‐hydroxyethyl methacrylate) poly (MMA‐co‐HEMA) with an optimum ratio of 75/25 (methyl methacrylate (MMA)/2‐hydroxyethyl methacrylate (HEMA)) was used as shell material to encapsulate paraffin wax (PCM), using emulsion solvent evaporation method. The microcapsules of ~5‐μm size with a shell thickness of ~0.8 μm with high encapsulation efficiency (~92.34%) and thermal storage capability (99.85%) were fabricated. In addition to ease of water dispersibility, PHEMA (poly(2‐hydroxyethyl methacrylate)) containing water absorbable shells also exhibit enhanced thermal conductivity from 0.1 to 0.49 W/(m·K) at 25°C in wet state compared with the dry capsule. The capsules show good durability by displaying no significant change in thermal properties and water dispersibility after running through 500 heating/cooling cycles. To test the feasibility of this novel water dispersible microencapsulated PCM, these were mixed with natural rubber latex at various blend ratios, and their thermal behaviour was evaluated. The obtained rubber composite showed good thermoregulation property with enhanced mechanical strength.

Antimicrobial functionalization of Ca alginate‐coconut oil latent heat storing microcapsules by Ag nanoparticles

“…To overcome these disadvantages and widen their application, microencapsulation provides important benefits such as increased heat transfer area, decreased supercooling, controlled volume change during melting and freezing, reactivity reduction and leakage prevention. 4 Coacervation, 5,6 emulsion-solvent evaporation, 7,8 polymerization, 9 spray drying, 10 sol-gel methods 11 and coating techniques 12 have been widely used for the microencapsulation of PCMs.…”

Optical Characterization of Bitumen: Inspecting the Quantum Size Effect in the Nanostructured Phase

“…Noticeably a series of references refer to diffraction peaks around 21 and 23°, attributed to different diffraction planes in paraffin waxes, consequently, a crystalline phase. [26][27][28] Liu et al 29 attribute diffraction peaks at 21.17 and 23.53°to, respectively, diffraction by the planes (110) and ( 200), as extracted from JCPDS card no. 40-1995. From these results we are sure we found a degree of crystallinity in our sample of BIT, and that these s Figs.…”

Encapsulation methods for phase change materials – A critical review

“…Khan et al [122] explored a novel shell material, poly (methyl methacrylate-co-2-hydroxyethyl methacrylate) [poly (MMA-co-HEMA)], to encapsulate paraffin wax as core material (see Fig. 26 ).…”