Preparation of coated thermo‐regulating textiles using Rubitherm‐RT31 microcapsules

Spherical microcapsules with a 49 wt % of Rubitherm^® RT31 were successfully synthesized by means of suspension‐like polymerization to be used for textile applications in summer conditions. Microcapsules were fixed into seven fabric substrates for different textile applications by a coating technique without deteriorating original functionalities of the textiles. Thermal performance of different coated textiles with 35 wt % of microcapsules was evaluated by differential scanning calorimetry (DSC) and infrared thermography (IR) techniques and the physical characteristics of textiles with thermo‐regulating properties were examined by environmental scanning electron microscopy (ESEM). It was observed that all treated textile substrates allow to obtain thermo‐regulating properties with acceptable latent heat storage capacities. Results also indicated that the presence of microcapsules containing Rubitherm^® RT31 produces a significant thermal insulation effect during a cold to warm transition (20–45°C). Thus, this kind of microcapsules can be used to obtain textiles with thermal comfort‐related properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Core content and stability of n‐octadecane‐containing polyurea microencapsules produced by interfacial polymerization

Microencapsulation of phase change material (PCM) n‐octadecane was carried out by interfacial polymerization technique using core and bulk monomers as toluene‐2,4‐diisocyanate (TDI) and diethylene triamine (DETA), respectively. Cyclohexane was used as the solvent for TDI and n‐octadecane, which formed the oil phase. The effect of encapsulation procedure, core‐to‐monomer ratio (CM ratio) and PCM‐to‐cyclohexane (PC) ratio was investigated on core content, encapsulation efficiency, and stability of microcapsules. Using a modified procedure, the core content was found to increase with the increasing CM ratio and reached a maximum at 3.7, while the encapsulation efficiency continuously decreased with the increasing CM ratio. Also the encapsulation efficiency was found to have a strong dependence on PC ratio and a maximum encapsulation efficiency of 92%, along with the core content of 70% was obtained with CM ratio of 3.7 along with the PC ratio of 6. The microcapsules were well shaped, i.e., round and regular, with narrow size distribution at these conditions. The PCM microcapsules were found to be stable to heat treatment at 150°C for 8 h. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Fabrication and thermal properties of microPCMs: Used melamine‐formaldehyde resin as shell material

An in‐situ polymerization process prepared a series of melamine formaldehyde (MF) microcapsules containing phase change material (PCM) as core material. The phase change temperature of this PCM was 24°C and its phase transition heat was 225.5 J/g. The microencapsulated phase change materials (MicroPCMs) were bedded in indoor‐wall materials to store and release heat energy, which would economize heat energy and make the in‐door condition comfortable. We investigated the structural formation mechanism by microscope and scanning electron microscopy (SEM). The superficial morphology measurements indicated the optimal shell material dropping rate 0.5 mL min^?1, double‐shell, and temperature elevating speed 2°C/10 min. The results obtained in the present investigation were reasonably understood on the basis of getting determinate rigidity and compacted shell. Also, the observed results were used to control the mass of shell material to get desired thickness of shell. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2006     

Preparation of phase change materials microcapsules by using PMMA network‐silica hybrid shell via sol‐gel process

Encapsulation of phase change materials (PCM) using a poly(methyl methacrylate) network‐silica hybrid as the shell material has been developed. n‐Octadecane melted at 28°C was used as PCM. Based on the suspension polymerization process, the microcapsules were prepared successfully by mixing and by the reaction of ethylene glycol dimethacrylate with precopolymer solution with tetraethoxysilane (TEOS), whose resultant microcapsules had higher latent heat (ΔH = 151 J/g) than those without TEOS (ΔH = 88.3 J/g). The average size of the PCM microcapsules was about 10 μm. The silica content, n‐octadecane content, and latent heat of microcapsules were changed with varying ageing conditions, ageing time, and temperature. The highest amount of latent heat (ΔH = 178.9 J/g) and n‐octadecane content (73.3%) of the microcapsule were obtained when the inorganic/organic ratio of the microcapsule was 5%. It was difficult to increase n‐octadecane content (74% to 55.7–67.9%) and latent heat (180.5 J/g to 135.9–165.7 J/g) of the microcapsules by introducing different functional groups of coupling agents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fragrance‐Containing Microcapsules Based on Interfacial Thiol‐Ene Polymerization

In this study, microcapsules containing fragrance oils as active agent were synthesized by interfacial thiol‐ene polymerization in oil‐in‐water emulsion. One water‐soluble dithiol and four oil‐soluble acrylates were used as “click”able monomers. The polymerization kinetics was studied by HPLC and ¹H‐NMR. The size and morphology of the microcapsules were characterized by means of light scattering, optical microscope, and scanning electron microscope, and their thermal property was examined by TGA. The encapsulation efficiency and stability of the microcapsules were monitored at room temperature and 45 °C for 1 month. In general, this interfacial thiol‐ene polymerization was demonstrated to be a facile and efficient approach for fragrance microencapsulation with new and stable shell materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43905.     

Functionalization of wool fabric with phase‐change materials microcapsules after plasma surface modification

The use of microcapsules has increased in several different areas, namely, textile applications. They have been used as a possible means of introducing new properties, namely, in medical care by antibiotics, skin moisturizers, and other drugs and for thermal comfort. In this study, we examined the influence of dielectric barrier discharge (DBD) plasma treatment on the adhesion of phase‐change material (PCM) microcapsules on wool fabric. Several experimental techniques were used to evaluate the wool surface modification after plasma treatment and the influence of the microcapsules' resistance to washing conditions, namely, the determination of the static and dynamic contact angles, surface energy, and adhesion work; X‐ray photoelectron spectroscopy; Fourier transform infrared spectroscopy; differential scanning calorimetry; and scanning electron microscopy. Chemical and physical characterization of the wool fiber in the fabric confirmed significant surface modification. The plasma treatment greatly increased the hydrophilicity, surface energy, and adhesion work of the wool fabric; this proved that more microcapsules were adsorbed on the fabric and more microcapsules remained on the fabric surface after the washing procedures. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of polyacrylate/paraffin microcapsules and its application in prolonged release of fragrance

The purpose of the present work was to develop a fragrance encapsulation system using polyacrylate/paraffin microcapsules. The Polyacrylate/paraffin microcapsules were fabricated by the method of suspension polymerization in Pickering emulsion. Morphology, size distribution, and thermal resistance of polyacrylate/paraffin microcapsules were investigated by scanning electron microscopy, light scattering particle size analyzer, and thermogravimetric analyzer. Results indicated that the crosslinked PMMA/paraffin microcapsules and P(MMA‐co‐BMA)/paraffin microcapsules prepared under optimal conditions presented regular spherical shape and similar size distribution. The crosslinked P(MMA‐co‐BMA)/paraffin microcapsules exhibited better thermal stability, with a thermal resistance temperature up to 184 °C. Fragrance microcapsules were prepared by encapsulating fragrance into crosslinked P(MMA‐co‐BMA)/paraffin microcapsules. The prolonged release performance of fragrance microcapsules was measured by ultraviolet‐visible near‐infrared spectrophotometer. 63.9% fragrance was retained after exposing fragrance microcapsules in air for 3 months, and the fragrance continued to release over 96 h in surfactant solution (sodium lauryl sulfonate, 20 wt %). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44136.     

Microencapsulation of triglycidyl isocyanurate by solvent evaporation method for UV and thermal dual‐cured coatings

Triglycidyl isocyanurate (TGIC), a thermal curing agent, was encapsulated with poly(methyl methacrylate) with small particle size and narrow distribution for the application in acrylic resins to prepare one‐package UV and thermal dual‐cured coatings. Investigation of the wettability and thermal properties suggests that the microcapsules have better compatibility with acrylic resins and thermal stability as compared to pure TGIC. Results of the release performance experiments indicate good storage stability at 25°C and a quick release of vast TGIC at 120°C for the microcapsules. The UV‐thermal dual‐cured coatings prepared with the microcapsules exhibit a fast, even and complete hardening at 130°C together with an excellent adhesion to the mild steel panels. The results presented here show an application potential of the microcapsules in UV and thermal dual‐cured paints. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41008.     

The microencapsulation of calcium chloride hexahydrate as a phase‐change material by using the hybrid coupler of organoalkoxysilanes

A novel method of microencapsulation for inorganic salt hydrates as phase‐change material (PCM), which is essential for their broad application, was pursued by combining sol–gel process with interfacial polymerization. Calcium chloride hexahydrate (CCH), chosen as a representative PCM of salt hydrates, was used as a core material, and organoalkoxysilane was applied to provide hybrid properties of mediating the hydrophilic core and hydrophobic shell material. The Fourier transform infrared spectra and SEM images confirmed that the siloxane and polyurea shell material successfully capsulated the CCH core. Fine morphology of microcapsules was further investigated with SEM, and it presented almost‐spherical shape and a well‐defined core–shell structure. Thermogravimetric analysis indicated that microcapsules containing CCH have sufficient thermal stability, which usually degraded in four steps. Differential scanning calorimeter investigation confirmed additionally that the microencapsulated CCH absorbs thermal energy with phase change during the melt process but undergo a severe super cooling phenomenon in the crystallizing process. In addition, the durability test was conducted to evaluate the siloxane polymer and polyurea as a shell material, protecting CCH from leaking. The effect of pH and the ratio of ingredients were studied in terms of encapsulation possibility and performance of core PCM, which include morphology of core–shell particles and essential thermal properties as a PCM. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45821.     

Mechanical properties and thermal stability of double‐shell thermal‐energy‐storage microcapsules

Double‐shell‐structured microcapsules encapsulating phase‐change materials (micro‐PCMs) with an average diameter of 5–10 μm were successfully fabricated with a melamine–formaldehyde resin as the coating material. The mechanical properties of the obtained piled micro‐PCMs, tested under compression, were evaluated with a pressure sensor. Typical stress–strain curves showed that both the single‐shell‐ and double‐shell‐structured microcapsules had yield points and maximum point pressures. The morphological changes in the shell surface confirmed the existence of yield points by scanning electron microscopy. When the pressure was beyond the yield point, the microcapsules showed conventional plastic behavior, and the double‐shell structure was more mechanically stable than the single‐shell one. Differential scanning calorimetry analysis results revealed that the properties of the phase‐change materials experienced no variation after coating with a single‐shell‐ or double‐shell‐structured polymer. Thermogravimetric analysis showed that the double‐shell‐structured micro‐PCMs experienced a weight loss of only about 5% from 86.3 to 232°C but did so more rapidly from 232 to 416°C. Thermoregulation was determined with periodical heating and cooling tests. The data showed that the micro‐PCMs changed temperature in a narrow range of 20–25°C with a time lag of 20 min to reach the maximum or minimum temperature in comparison with a reference temperature of 18–28°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1295–1302, 2007     

Preparation of paraffin-based phase-change microcapsules and application in geopolymer coating

A type of paraffin phase-change microcapsule for thermal insulation of exterior walls was prepared by in situ polymerization of low-softening-point paraffin (46°C) as core material and acrylic copolymer as shell. The surface morphology, phase-change thermal properties, and thermal stability were characterized by scanning electron microscopy, laser particle size distribution analysis, differential scanning calorimetry, and thermogravimetric analysis, respectively. The results showed that, for polymerization reaction temperature of 75°C and paraffin/acrylic copolymer mass ratio of 1.8, the microcapsules prepared at rotation speed of 1600 r/min with 8% emulsifiers were spherical particles with smooth surface and average particle size of 0.68 μm. The phase-change temperature and latent heat storage capacity of the microcapsules were 47.8°C and 174 J/g, respectively. The paraffin phase-change microcapsules obtained using the optimum synthesis condition were mixed in a metakaolin-based geopolymer coating at different proportions, and the thermal insulation ability of the resulting phase-change thermal energy storage coating characterized.     

Preparation and thermal energy storage properties of poly(n‐butyl methacrylate)/fatty acids composites as form‐stable phase change materials

This work is focused on the preparation, characterization, and determination of thermal energy storage properties of poly(n‐butyl methacrylate) (PnBMA)/fatty acid composites as form‐stable phase change material (PCM). In the composite materials, the fatty acids act as latent heat storage material whereas PnBMA serves as supporting material, which prevents the leakage of the melted fatty acids. The maximum encapsulation ratio for all fatty acids was found to be 40 wt%. The composites that do not allow PCM leakage in melted state were identified as form‐stable PCMs. The compatibility of fatty acids with PnBMA is investigated by optical microscopy (OM) and Fourier Transform Infrared (FT‐IR) spectroscopy. Thermal properties and thermal reliability of the form‐stable composite PCMs were determined using differential scanning calorimetry (DSC). DSC analysis revealed that the form‐stable composite PCMs had melting temperatures between 29.62°C and 53.73°C and latent heat values between 67.23 J/g and 87.34 J/g. Thermal stability of the composite PCMs was studied by thermal gravimetric (TG) analysis and the results indicated that the form‐stable PCMs had good thermal stability. In addition, thermal cycling test showed that the composite PCMs had good thermal reliability with respect to the changes in their thermal properties after accelerated 5,000 thermal cycling. On the basis of all results, it was also concluded that the prepared form‐stable composite PCMs had important potential for many thermal energy storage applications such as solar space heating of buildings by using wallboard, plasterboard or floors integrated with PCM. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Preparation,characterization, and prominent thermal stability of phase‐change microcapsules with phenolic resin shell and n‐hexadecane core

Microcapsules with phenolic resin (PFR) shell and n‐hexadecane (HD) core were prepared by controlled precipitation of the polymer from droplets of oil‐in‐water emulsion, followed by a heat‐curing process. The droplets of the oil phase are composed of a polymer (PFR), a good solvent (ethyl acetate), and a poor solvent (HD) for the polymer. Removal of the good solvent from the droplets leads to the formation of microcapsules with the poor solvent encapsulated by the polymer. The microstructure, morphology, and phase‐change property as well as thermal stability of the microcapsules were systematically characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimety (DSC), and thermogravimetric analysis (TGA). The phase‐change microcapsules exhibit smooth and perfect structure, and the shell thickness is a constant fraction of the capsule radius. The initial weight loss temperature of the microcapsules was determined to be 330°C in N₂ and 255°C in air, respectively, while that of the bulk HD is only about 120°C both in air and N₂ atmospheres. The weight loss mechanism of the microcapsules in different atmosphere is not the same, changing from the pyrolysis temperature of the core material in N₂ to the evaporation of core material caused by the fracture of shell material in air. The melting point of HD in microcapsules is slightly lower than that of bulk HD, and a supercooling was observed upon crystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of microencapsulated curing agents on the curing behavior for diglycidyl ether of bisphenol A epoxy resin systems

Microcapsules containing a curing agent, 2‐phenyl imidazole (2PZ), for a diglycidyl ether of bisphenol A (DGEBA) epoxy resin were prepared by a solid‐in‐oil‐in‐water emulsion solvent evaporation technique with poly(methyl methacrylate) (PMMA) as a polymeric wall. The mean particle size of the microcapsules and the concentration of 2PZ were about 10 μm and nearly 10 wt %, respectively. The onset cure temperature and peak temperature of the DGEBA/2PZ–PMMA microcapsule system appeared to increase by nearly 30 and 10°C, respectively, versus those of the DGEBA/2PZ system because of the increased reaction energy of curing. The former could take more than 3 months at room temperature, whereas the latter was cured after only a week. The values of the reaction order (a curing kinetic parameter) for DGEBA/2PZ and DGEBA/2PZ–PMMA microcapsules were quite close, and this showed that the curing reactions of the two samples proceeded conformably. The curing mechanism was investigated, and a two‐step initiation mechanism was considered: the first was assigned to adduct formation, whereas the second was due to alkoxide‐initiated polymerization. The glass‐transition temperature of DGEBA/2PZ was 165.2°C, nearly 20°C higher than the glass‐transition temperatures of DGEBA/2PZ–PMMA microcapsules and DGEBA/2PZ/PMMA microspheres, as determined by differential scanning calorimetry measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(divinylbenzene) Microencapsulated Octadecane for Use as a Heat Storage Material: Influences of Microcapsule Size and Monomer/Octadecane Ratio

Poly(divinylbenzene) (PDVB) microencapsulated octadecane (OD) (PDVB/OD) used as heat storage material were prepared by suspension polymerization at 70°C using benzoyl peroxide and polyvinyl alcohol as initiator and stabilizer, respectively. The influence of microcapsule size and divinylbenzene (DVB)/OD weight ratio on the microcapsule shape and thermal properties of encapsulated OD were considered. Thermal properties and thermal stability of PDVB/OD microcapsules were determined using differential scanning calorimeter (DSC) and thermogravimetric analyzer. The optical micrographs and scanning electron micrographs showed that the microcapsules have spherical shape only in the case of 50/50 (%w/w) of DVB/OD whereas they were nonspherical with the decreasing of DVB content. However, the core materials were still well encapsulated even increasing the OD content to 70%wt. From DSC analysis, in all cases, the melting temperature of encapsulated OD (28°C) was almost the same as that of bulk OD (30°C), yet it was quite different in the case of crystallization temperature (≤ 19°C and 25°C for encapsulated and bulk OD, respectively). The latent heats of melting and crystallization of encapsulated OD, in all conditions, were reduced from those of bulk OD (242 and 247 J/g, respectively).     

Expansion space and thermal stability of microencapsulated n‐octadecane

5.0–50.0 vt% of cyclohexane was mixed with 95.0–50.0 vt% of n‐octadecane as the oil‐phase during the emulsion process in the in situ polymerization of melamine‐formaldehyde. By heat‐treating the microcapsules in an oven at 100°C, the cyclohexane was removed and expansion space was formed inside the microcapsules. The microcapsules were characterized by using FTIR, SEM, DSC, TGA, and gas chromatography. When the microcapsules are heat‐treated at temperatures higher than 180°C, Tm, ΔHm, Tc, and ΔHc of the microcapsules decrease. The attenuation of enthalpy of the microcapsules containing expansion space is obviously lower than that of the control sample, however. The permeability of the microcapsule shell decreases with the increase of cyclohexane content. There is a maximum between the thermal stabilities of the microcapsules and the cyclohexane contents. The microcapsules synthesized with 30.0–40.0 vt% of cyclohexane have the highest thermal stabilities, with 230°C and 289°C in air and nitrogen atmosphere, respectively. The thermal stable temperatures are approximately 67°C and 102°C higher than that of the control sample, respectively. The expansion space inside the microcapsules allows the n‐octadecane to expand in the temperature rising process and exert lower pressure to the shell, therefore keeping the shell intact and increasing the thermal stabilities of the microcapsules. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 390–396, 2005     

Poly(ethylene glycol)/poly(methyl methacrylate) blends as novel form‐stable phase‐change materials for thermal energy storage

In this study, we focused on the preparation and characterization of poly(ethylene glycol) (PEG)/poly(methyl methacrylate) (PMMA) blends as novel form‐stable phase‐change materials (PCMs) for latent‐heat thermal energy storage (LHTES) applications. In the blends, PEG acted as a PCM when PMMA was operated as supporting material. We subjected the prepared blends at different mass fractions of PEG (50, 60, 70, 80, and 90% w/w) to leakage tests by heating the blends over the melting temperature of the PCM to determine the maximum encapsulation ratio without leakage. The prepared 70/30 w/w % PEG/PMMA blend as a form‐stable PCM was characterized with optical microscopy and Fourier transform infrared spectroscopy. The thermal properties of the form‐stable PCM were measured with differential scanning calorimetry (DSC). DSC analysis indicated that the form‐stable PEG/PMMA blend melted at 58.07°C and crystallized at 39.28°C and that it had latent heats of 121.24 and 108.36 J/g for melting and crystallization, respectively. These thermal properties give the PCMs potential LHTES purposes, such as for solar space heating and ventilating applications in buildings. Accelerated thermal cycling tests also showed that the form‐stable PEG/PMMA blend as PCMs had good thermal reliability and chemical stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and thermal properties of poly(n‐butyl acrylate)/n‐hexadecane microcapsules using different cross‐linkers and their application to textile fabrics

This study focused on the preparation, characterization, and determination of thermal properties of microencapsulated n‐hexadecane with poly(butyl acrylate) (PBA) to be used in textiles with heat storage property. Microcapsules were synthesized by emulsion polymerization method, and the particle size, particle size distribution, shape, and thermal storage/release properties of the synthesized microcapsules were analyzed using Fourier‐transform infrared spectroscopy, scanning electron microscopy, and differential scanning calorimetry techniques. Allyl methacrylate, ethylene glycol dimethacrylate, and glycidyl methacrylate were used as cross‐linkers to produce unimodal particle size distribution. MicroPBA microcapsules produced using allyl methacrylate cross‐linker were applied to 100% cotton and 50/50% cotton/polyester blend fabrics by pad‐cure method. The mean particle size of microcapsules ranges from 0.47 to 4.25 μm. Differential scanning calorimetry analysis indicated that hexadecane in the microcapsules melts at nearly 17°C and crystallizes at around 15°C. The contents of n‐hexadecane of different PBA microcapsules were in the range of 27.7–50.7%, and the melting enthalpies for these ratios were between 65.67 and 120.16 J/g, respectively. The particle size and thermal properties of microcapsules changed depending on the cross‐linker type. The cotton and 50/50% cotton/polyester blend fabrics stored 6.56 and 28.59 J/g thermal energy, respectively. The results indicated that PBA microcapsules have the potential to be used as a solid‐state thermal energy storage material in fabrics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Storage stability and solubility of poly(urea‐formaldehyde) microcapsules containing A‐olefin drag reducing polymer

Microcapsules containing α‐olefin drag reducing polymer were prepared by in situ and interfacial polymerization with urea, formaldehyde, and styrene as shell materials, respectively. IR spectrums of prepared shells indicated the formations of poly(urea‐formaldehyde) and polystyrene in the microencapsulating process. The morphologies of uncoated particles and microcapsules were observed by scanning electron microscopy (SEM) which proved that the α‐olefin drag reducing polymer particles were effectively coated. For the purpose of determining the stability of microcapsules in transportation and storage, the static pressure experiment was carried out and lasted for 6 months. In this process, microcapsules with polystyrene as shell material stuck together after 3 months; however, those with poly(urea‐formaldehyde) kept the state of particles. The thermal characteristics of uncoated particles (core), poly(urea‐formaldehyde) (shell), and microcapsules with that as shell material were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) which proved that thermal stable temperature of microcapsules containing α‐olefin drag reducing polymer with poly(urea‐formaldehyde) as shell material was below 225°C, and the mean heat absorbed by microcapsules in the temperature increasing process was 1.5–2.0 W/g higher than that by cores. The evaluation of drag reducing rate of microcapsules showed that the microencapsulating process had no influence on the drag reduction of α‐olefin drag reducing polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of double‐MF shell microPCMs used in building materials

A kind of double‐shell heat energy storage microcapsule was prepared used melamine formaldehyde (MF) resin as shell material, and the properties of the microcapsules were investigated. A phase change material, with melt point of 24°C and phase transition heat of 225.5J/g, was used as core. The microcapsules would be used in indoor walls to regulate the temperature and save energy. The surface morphological structure was examined by means of scanning electron microscopy. The strength of the shell was evaluated through observing the surface change after pressure by means of scanning electron microscopy. The average diameter of the microcapsules was 5 μm ～ 10 μm. Diameter of 1 μm ～ 5 μm could also be obtained by using different stirring speeds. The globular surface was smooth and compact. The thickness was 0.5 μm ～ 1 μm. Also, the melting point of the microcapsules was 24.7°C, nearly equal to the pure phase change material. The DSC results make clear that the polymer shell of the microcapsules does not influence the properties of the phase change material. It was also found that the avoiding penetration property of the double‐shell microcapsules was better than that of single shell, and the average diameter of 5 μm was better than 1 μm. With the increase of ratio of the core material, the compactability decreased, and the shell thickness decreased. The mass ratio of core and shell was 3 : 1 to ensure that the microcapsules had good heat storage function. The measuring test showed that the microcapsules did not rupture at a pressure of 1.96 × 10⁵ Pa. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1755–1762, 2005