A kind of phase change material capsule and preparation method thereof

A technology of phase change materials and capsules, applied in the field of phase change material capsules and its preparation, phase change material microcapsules or nanocapsules, can solve the problem of poor anti-supercooling crystallization effect of paraffin, reduce the effective content of n-octadecane, research results Unsatisfactory problems, to achieve the effect of eliminating supercooled crystallization, good thermal stability, and easy industrial implementation

Active Publication Date: 2015-08-26
TIANJIN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although supercooled crystallization is a common phenomenon in the cooling process of PCM, the supercooled crystallization of PCM in MicroPCMs and NanoPCMs makes the exothermic process occur at a wider temperature range or lower temperature, which seriously affects the energy storage function.
In order to effectively eliminate or reduce the supercooled crystallinity, the inventors studied (see Colloid and Surface Science Journal, Journal of Colloid and Interface Science, 2005, 281 (2): 299-306) the mass fraction of 5-30% Effects of 1-tetradecyl alcohol, 1-stearyl alcohol and paraffin wax with a melting point of 56°C on the supercooled crystallization of n-octadecane in MicroPCMs. As an anti-supercooled crystallization additive, 1-octadecyl alcohol cannot be achieved because it affects cystic formation. to the best effect; when the paraffin mass fraction was 20%, MicroPCMs with lower degree of supercooled crystallization and better encapsulation could be prepared, but the effective content of n-octadecane in MicroPCMs was reduced, and the diameter of MicroPCMs increased The smaller the paraffin, the worse the anti-supercooled crystallization effect
[0004] Other researchers (see Journal of Thermal Analysis and Calorimetry, Journal of Thermal Analysis and Calorimetry, 2006, 86(2): 505-509) added modifiers such as nano-silica to MicroPCMs in an attempt to prevent them from overcooling Crystallization occurs, but results are not ideal

Method used

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Effect test

preparation example Construction

[0052] The present invention also designs a capsule preparation method (abbreviated as the preparation method), which adopts the mass fraction composition of the capsule of the present invention and the following process: the mass fraction of polymerized monomer, phase change material, emulsifier and initiator Mixing agent and dispersant, and then the mixture is mechanically stirred or ultrasonically oscillated at a temperature of 10 to 90 ℃, and the particle size of the emulsion in the emulsion is observed at any time with an optical microscope or environmental scanning electron microscope until the particle size of the emulsion reaches 1 to 1000 microns or less than the design requirements, and then under the action of the initiator, the monomers are polymerized, and the phase change material capsules are prepared by the suspension polymerization method or the in-situ polymerization method. In the process of preparing the phase change material capsule, the mass fraction of the...

Embodiment 1

[0065] At 90°C, 9 g of pentadecyl acrylate, 35 g of methyl acrylate, 6 g of ethylene glycol dimethacrylate, 164 g of phase change material n-octadecane, 2 g of initiator azobisisoheptanonitrile, and 780 g of deionized water were prepared. 4g of emulsifier sodium lauryl sulfate was mixed and mechanically stirred at 9000 rpm for 2 hours. The average diameter of the droplets was 0.7 microns, and then stirred at 500 rpm for 6 hours; the stirring was stopped, the water was circulated and cooled to room temperature, the mixed emulsion was separated by filtration, and the mass of 2500 g was removed. After rinsing the product with ionized water for 3 times, it is dried to constant weight in a vacuum oven at 50° C. to obtain dry powder of phase change material nanocapsules.

[0066] After testing, the average particle size of the phase change material nanocapsules obtained is 0.9 microns, and the crystal melting endothermic temperature (T m ) Is 28.5℃, enthalpy of fusion (ΔH m ) Is 181J / g,...

Embodiment 2

[0068] At 90° C., 2 g of 34 acrylate, 46 g of methyl methacrylate, 2 g of pentaerythritol tetraacrylate, 164 g of oleophilic phase change material n-hexadecane, 2 g of initiator azobisisoheptonitrile, and emulsifier 12 Mix 4 g of potassium alkyl sulfate and 780 g of deionized water, stir at 10000 rpm for 2 hours, and the average diameter of the emulsion droplets is 0.4 micron, and then stir at 600 rpm for 6 hours; stop stirring to obtain a phase change material nanocapsule emulsion.

[0069] After testing, the average particle size of the phase change material microcapsules obtained is 0.6 microns, T m Is 18.7℃, ΔHm is 178J / g, T c It is 15.3℃, compared with n-hexadecane, there is no obvious supercooling crystallization phenomenon, ΔH c 176J / g, T d It is 255°C.

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Abstract

The invention discloses a phase-change material capsule and a preparation method thereof. The capsule uses a phase-change material as a capsule core and is characterized in that: a capsule wall material of the capsule at least comprises a monomer I polymer. The phase-change material capsule comprises the following materials in percentage by mass: 20.8 to 84.3 percent of phase-change material, 9 to 72.5 percent of monomer I, 0.4 to 4.5 percent of emulsifying agent and 0.1 to 2.2 percent of initiator, wherein the monomer I is a monomer comprising a crystallizable branch and comprises but not limited to at least one of crylic acid alkyl ester of which the branch contains 10 to 50 carbon atoms or methacrylic acid alkyl ester of 10 to 50 carbon atoms; the alkyl has a straight chain structure; the emulsifying agent is a micromolecule emulsifying agent and comprises an anionic, cationic, nonionic or polymer emulsifying agent; and the initiator comprises but not limited to a radical initiator or an oxidation-reduction initiator. In the preparation method, the phase-change material capsule is prepared by a suspension polymerization method or an in-situ polymerization method.

Description

Technical field [0001] The present invention relates to phase change material technology, in particular to a phase change material capsule and a preparation method thereof. The capsule is a phase change material microcapsule or nanocapsule with thermal energy storage and utilization functions. Background technique [0002] Clean and green energy storage materials have a particularly important strategic position in the national economy and have been a long-term research focus. Phase change material (PCM) is an energy-saving and environmentally friendly material developed and applied after the 1970s, and it is also a clean and recyclable energy storage material. Phase change materials can absorb or release a large amount of latent heat of phase change in the process of solid-liquid, solid-gas, liquid-gas, and solid-solid phase transitions, and are widely used in HVAC, energy-saving buildings, solar energy utilization, clothing and other fields , Is of great significance in terms o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K5/06B01J13/14
Inventor 张兴祥王建平石海峰王学晨廖晓华
Owner TIANJIN POLYTECHNIC UNIV
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