Synthesis of monodispersed paraffin microcapsules by polycondensation using membrane emulsification and their latent heat properties

Jung, Yeonseok; You, Jin-Oh; Youm, Kyung-ho

doi:10.1007/s13233-015-3134-x

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…Paraffin is a common core material of phase-change microcapsules because of its high latent heat, wide phase-change temperature, and no supercooling. Microencapsulated PCMs with a paraffin core possess wide-application prospects in electronic devices, textiles, and buildings …”

Section: Introductionmentioning

confidence: 99%

“…Microencapsulated PCMs with a paraffin core possess wide-application prospects in electronic devices, 9 textiles, 10 and buildings. 11 Both inorganic chemicals and organic polymers can be packed in the PCM core. 12 Among them, organic polymers are widely utilized in PCM microcapsules because of their excellent mechanical properties and chemical resistance, 13 such as melamine formaldehyde (MF), 14,15 urea formaldehyde, 16 polymethyl methacrylate, 17 polystyrene, 18 polyurea (PU), 19 and so forth.…”

Section: ■ Introductionmentioning

confidence: 99%

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Nanodiamond-Modified Microencapsulated Phase-Change Materials with Superhydrophobicity and High Light-to-Thermal Conversion Efficiency

Zhao

et al. 2020

Ind. Eng. Chem. Res.

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A series of novel paraffin (Pn)@nanodiamond (ND)/melamine formaldehyde microencapsulated phase-change materials (microPCMs) with superhydrophobicity and high lightto-thermal conversion efficiency were synthesized through in situ polymerization. ND, acting as a kind of thermally conductive particle, was situated at the interface between the core and the shell. We have investigated the effect of different ND contents on the morphology, microstructure, and properties of microPCMs through scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, thermal conductivity test, paraffin leakage rate test, photothermal conversion test, and contact angle (CA) measurements. The results show that the thermal conductivity of microPCMs with ND was significantly improved. The microPCMs exhibited appropriate phase-change temperatures and achieved a high-encapsulation efficiency. Moreover, the water CA of microPCMs was 159.9°, which displayed superhydrophobic properties. When the dose of ND was 6 g/L, the light-to-thermal conversion efficiency of microPCMs was up to 64.7%, greatly improving the light-to-thermal conversion performance. Thus, the microPCMs with high light-to-thermal conversion performance and superior superhydrophobic property might be a potential material for energy conversion and hydrophobicity.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Nanodiamond-Modified Microencapsulated Phase-Change Materials with Superhydrophobicity and High Light-to-Thermal Conversion Efficiency

Zhao

et al. 2020

Ind. Eng. Chem. Res.

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“…Organic and inorganic shells are used for microencapsulation of paraffins and other organic PCMs. The inorganic capsules, mostly silica and titania or graphene oxide and metallic silver decorations provide improved thermal conductivity, fire retardation, and compatibility with inorganic building ingredients and flow systems . However, it is practically impossible to maintain hermetic encapsulation of the small organic molecule melts within inorganic shells and retain zero leakage after many hundreds of freeze‐thaw cycles, particularly when the weight fraction of the shell is to be kept low.…”

Section: Introductionmentioning

confidence: 99%

Doubly Coated, Organic–Inorganic Paraffin Phase Change Materials: Zinc Oxide Coating of Hermetically Encapsulated Paraffins

Mikhaylov

Medvedev

Grishanov

et al. 2019

Adv Materials Inter

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Paraffins, and organic PCMs in general, are less corrosive and have lower freezethaw hysteresis compared to inorganic ones. However, paraffins are flammable and have lower thermal conductivity (around 0.2 J K −1 g −1 ) compared to metal salt hydrates and eutectic inorganic PCMs. [1][2][3][4][5] After melting, organic PCMs tend to coalesce, and form thick thermal insulating layers or large particles that are incompatible with flow systems. In addition, biocides, fire retardants and other additives tend to segregate out upon thermal cycling. One remedy to these drawbacks is microencapsulation to prevent segregation and coalescence. Organic and inorganic shells are used for microencapsulation of paraffins and other organic PCMs. The inorganic capsules, mostly silica and titania or graphene oxide and metallic silver decorations provide improved thermal conductivity, fire retardation, and compatibility with inorganic building ingredients and flow systems. [6][7][8][9][10][11][12] However, it is practically impossible to maintain hermetic encapsulation of the small organic molecule melts within inorganic shells and retain zero leakage after many hundreds of freeze-thaw cycles, particularly when the weight fraction of the shell is to be kept low. Organic microcapsules offer better flexibility, and they also prevent leakage better, but they have lower thermal conductivity, lower flame retardation and lower compatibility with polar fluids and with inorganic building materials. A third way, proposed in this article, is to merge the two approaches: uniform coating of the paraffin core by organic polymer and external coating of the latter by an inorganic thin film as to maximize heat transfer and to endow the PCMs with the favorable properties of inorganic materials.In this article, we introduce the synthesis of a zinc oxide coating onto organically encapsulated paraffin PCM substrates based on hydrogen peroxide sol-gel processing. A somewhat related approach involves the decoration of organic PCM capsules with silver metal spots and graphene oxide, though both alternatives rely on expensive additives. [11,13] We show that the coating process can be conducted at low temperature, which does not damage the capsule or evaporate the organic core. Coating of capsules of paraffins by metal and metalloid oxides is not an easy task. Whereas the low temperature, thin film coating of large flat surfaces by spray-, dip-, spin-, and A way to benefit from the favorable attributes of both organic microencapsulation, including the hermetic sealing of the organic phase change material (PCM) core, and inorganic microencapsulation, including dispersibility in aqueous and polar solvents and improved thermal conductivity, is outlined. The approach is demonstrated by uniformly coating organic polymer encapsulated PCMs with zinc oxide, which allows thermal percolation through the interconnected inorganic shells. It is demonstrated that hydrogen peroxide sol-gel processing can be used to form such uniform zinc peroxide coatings which are then conv...

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Hydrogen peroxide sol–gel coating of microencapsulated phase change materials by metal oxides

Mikhaylov

Medvedev

Grishanov

et al. 2020

J Sol-Gel Sci Technol

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Synthesis of monodispersed paraffin microcapsules by polycondensation using membrane emulsification and their latent heat properties

Cited by 8 publications

References 28 publications

Nanodiamond-Modified Microencapsulated Phase-Change Materials with Superhydrophobicity and High Light-to-Thermal Conversion Efficiency

Nanodiamond-Modified Microencapsulated Phase-Change Materials with Superhydrophobicity and High Light-to-Thermal Conversion Efficiency

Doubly Coated, Organic–Inorganic Paraffin Phase Change Materials: Zinc Oxide Coating of Hermetically Encapsulated Paraffins

Hydrogen peroxide sol–gel coating of microencapsulated phase change materials by metal oxides

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