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Microencapsulation of n -octadecane or paraffin with poly(lauryl methacrylate) (PLMA) shell was performed by a suspension-like polymerization. The polymer shell was crosslinked by pentaerythritol tetraacrylate (PETRA). The surface morphologies of microcapsules were investigated by scanning electron microscopy (SEM). Phase change properties, thermal reliabilities and thermal stabilities of microcapsules were determined by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The n -octadecane microcapsule exhibits higher melting enthalpy (118.0 J g −1 ) and crystallization enthalpy (108.3 J g −1 ) compared with the paraffin microcapsule. The thermal resistant temperatures were enhanced by more than 25 °C when n -alkanes were microencapsulated by PLMA. The PCM contents of microcapsules decreased by less than 4 wt% and 6 wt% after 500 and 1000 thermal cycles, respectively. Heat-up experiments indicated that microcapsule-treated foams exhibited upgraded thermal regulation capacities. Consequently, microencapsulated n -octadecane or paraffin with PLMA as shell possesses good potentials for heat storage and thermal regulation. [ABSTRACT FROM AUTHOR]

This paper was aimed to prepare, characterize and determine the comprehensive evaluation of promising composite macrocapsules containing microencapsulated PCMs (phase change materials) with calcium alginate gels as the matrix material. Macrocapsules containing microcapsules were fabricated by piercing-solidifying incuber method. Two kinds of microcapsules with n-tetradecane as core material, UF (urea-formaldehyde) and PMMA (poly(methyl methacrylate)) respectively as shell materials were prepared initially. For application concerns, thermal durability and mechanical property of macrocapsules were investigated by TGA (thermal gravimetric analysis) and Texture Analyser for the first time, respectively. The results showed excellent thermal stability and the compressive resistance of macrocapsules was sufficient for common application. The morphology and chemical structure of the prepared microcapsules and macrocapsules were characterized by SEM (scanning electron microscopy) and FT-IR (fourier transform infrared) spectroscopy method. Phase change behaviors and thermal durability of microcapsules and macrocapsules were investigated by DSC (differential scanning calorimetry). In order to improve latent heat of composite microcapsules, the core-shell weight ratio of tetradecane/UF shell microcapsules was chosen as 5.5:1 which obtained the phase change enthalpy of 194.1 J g −1 determined by DSC. In conclusion, these properties make it a feasible composite in applications of textile, building and cold-chain transportation. [ABSTRACT FROM AUTHOR]

ABSTRACT Microcapsules containing paraffin and diethyl ethylphosphonate (DEEP) flame retardant with uncrosslinked and crosslinked poly (methacrylic acid- co-ethyl methacrylate) (P(MAA- co-EMA)) shell were fabricated by suspension-like polymerization. The surface morphologies of the microencapsulated phase change materials (microPCMs) were studied by scanning electron microscopy. The thermal properties and thermal stabilities of the microPCMs were investigated by differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The flame retarding performances of the microcapsule-treated foams were calculated by using an oxygen index instrument. The DSC results showed that the crosslinking of the polymer shell led to an increase in the melting enthalpies of the microcapsule by more than 15%. The crosslinked P(MAA- co-EMA) microcapsules with DEEP and without DEEP have melting enthalpies of 67.2 and 102.9 J/g, respectively. The TGA results indicated that the thermal resistant temperature of the crosslinked microcapsules with DEEP was up to 171°C, which was higher than that of its uncrosslinked counterpart by ∼20°C. The incorporation of DEEP into the microPCM increased the limiting oxygen index value of the microcapsule-treated foams by over 5%. Thermal images showed that both microcapsule-treated foams with and without DEEP possessed favorably temperature-regulated properties. As a result, the microPCMs with paraffin and DEEP as core and P(MAA- co-EMA) as shell have good thermal energy storage and thermal regulation potentials, such as thermal-regulated foams heat insulation materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41880. [ABSTRACT FROM AUTHOR]

Microcapsules containing n -octadecane with different n -butyl methacrylate (BMA)-based copolymer shells were fabricated by a suspension-like polymerization method. n -butyl acrylate (BA), methacrylic acid (MAA) and acrylic acid (AA) were employed as monomers to copolymerize with BMA. The surface morphologies of the microencapsulated phase change materials (MicroPCMs) were studied by scanning electron microscopy (SEM). The thermal properties, thermal reliabilities and thermal stabilities of the MicroPCMs were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The temperature-regulated properties of the MicroPCMs were determined by an infrared thermography. The incorporation of MAA or AA to the acrylic composition of the polymer shells led to an increase in both the heat storage capacities and thermal stabilities of the MicroPCMs. The MicroPCMs with P(BMA-co-MAA) exhibit a greater heat capacity and thermal stability compared with the MicroPCMs with P(BMA-co-AA). The MicroPCMs with P(BMA-co-MAA) have the highest latent heats of melting (144.3 J/g) and crystallization (152.9 J/g) as well as the highest thermal resistant temperature (249 °C). The phase change temperatures and enthalpies of the MicroPCMs varied little after 1000 thermal cycles. Thermal images showed that the gypsum board containing the MicroPCMs with BMA-based copolymers as shells, especially with P(BMA-co-MAA) and P(BMA-co-AA) as shells, possessed temperature-regulated properties. As a result, the MicroPCMs with BMA-based copolymers as shells have good thermal energy storage and thermal regulation potentials, such as solar energy-saving building materials. [ABSTRACT FROM AUTHOR]

MicroPCMs (microencapsulated phase-change materials) were successfully synthesized using PMMA (poly(methyl methacrylate)) and UF (urea-formaldehyde) as raw materials for hybrid shells, and n -tetradecane as core materials. NMA ( n -methylol acrylamide) with two functional groups of double-bond and hydroxymethyl was used as a crosslinking agent. The morphologies and chemical structures of microPCMs were characterized using scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) spectroscopy. The agglomerations of the UF/PMMA hybrid samples might be influenced by two factors: cross linking action of NMA and PMMA/UF ratio in shell materials. The phase change properties and thermal durability were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), respectively. The UF/NMA/PMMA hybrid shell microcapsules has an enthalpy of 175.5 J/g which is higher than the single-layer shell samples of PMMA and UF, and a better leakproofness than the UF/PMMA hybrid samples without NMA owing to the semi-IPN microstructure. Likewise, the UF/NMA/PMMA hybrid samples have higher thermal durability than the single layer shell samples of PMMA and UF and the UF/PMMA hybrid samples without NMA. Moreover, the thermal cycling test of the UF/PMMA hybrid samples with NMA was carried out for 100 heating/cooling cycles and indicated that the developed hybrid shell microPCMs have good chemical stability and thermal reliability. The heating-up experiment revealed that the foam treated by microcapsules had a better thermoregulatory property than the raw foam. Based on the results obtained, it can be concluded that n -tetradecane/UF/PMMA microPCMs have potential thermal energy storage applications. [ABSTRACT FROM AUTHOR]