Preparation and Properties of Microencapsulated Phase Change Materials Containing Two-Phase Core Materials

Abstract

Microencapsulated phase change materials (MicroPCMs) containing two-phase core materials, in which polypyrrole (PPy) particles were homodispersed in n-octadecane (n-Oct), were synthesized by two-step polymerization technique using poly(methyl methacrylate-co-allyl methacrylate) as shell. The surface morphologies, phase change properties, and thermal stabilities of the microcapsules were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), respectively. The results show the two-phase core materials are well encapsulated in the presence of the emulsifier sodium salt of styrene−maleic anhydride copolymer. The average diameter of the microcapsules is about 35 μm. The crystallization temperature of MicroPCMs is higher than that of MicroPCMs without PPy. At the same time, the enthalpy of the heterogeneous nucleation significantly increased with increasing of the PPy concentration. Microcapsules with 4−14 wt % PPy in the core material were free from obvious supercooling, and PPy had no influence on the morphology, the particle distribution, or the thermal resistant temperature of microcapsules.

Improvements in the thermal conductivity and mechanical properties of phase‐change microcapsules with oxygen‐plasma‐modified multiwalled carbon nanotubes

“…This indicated that the modified CNTs were generated within the microPCMs. Wang et al 33 prepared microcapsules containing polypyrrole and C18 and discovered the same phenomenon. Moreover, the samples with the addition of modified CNTs into the polymer system were a darker gray, so it was easier to incorporate the modified CNTs into the surface layer of the microPCMs.…”

“…This indicated that the modified CNTs were generated within the microPCMs. Wang et al . prepared microcapsules containing polypyrrole and C18 and discovered the same phenomenon.…”

“…However, as shown distinctly in Figure (d–g), all of the surfaces of the microPCMs had some dimples. The reason was that C18 shrank from the melting state to the crystal state during the phase‐change process as a result of the shrinkage of expansion space . Furthermore, S0 without modified CNTs had a relatively large dimple, the microPCMs (S1, S2, and S3) with the addition of modified CNTs into the emulsion system had even more small dimples, and the microPCMs (S4, S5, and S6) with the addition of modified CNTs into the polymer system showed fewer and inconspicuous small dimples with increasing amount of modified CNTs.…”

Different Phase Change Material Implementations for Thermal Energy Storage

“…They succeeded in eliminating the supercooling from the MEPCM by adding 4-14 wt% PPy in the core, while PPy had no influence on the morphology and particle distribution of the microcapsules. A new hybrid shell of polymer/SiO2 was used by Yin et al [47] to encapsulate dodecanol as a core material. They successfully eliminated the surfactant or dispersant material by using the organically modified SiO2 particles.…”

A simple sonochemical method for fabricating poly(methyl methacrylate)/stearic acid phase change energy storage nanocapsules

“…The encapsulation technique depends on the physical and chemical properties of the materials used. To date, there are several physical and chemical methods used for the production of nano or micro capsules [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. However, the common problem with these methods is that they all require a complex or time-consuming preparation process.…”