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     

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     

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     

Nanocapsules containing binary phase change material obtained via miniemulsion polymerization with reactive emulsifier: Synthesis,characterization, and application in fabric finishing

The nanocapsules containing n‐butyl stearate (BS) and n‐octadecane (C18) as binary phase change material and polyacrylate as shell were synthesized via miniemulsion polymerization using reactive emulsifier. The phase transition (change) temperatures and phase change enthalpies of the phase change material can be adjusted by regulating the composition of BS and C18. Moreover, the influences of emulsification method and reactive emulsifier dosage were studied. SEM and TEM analysis showed the nanocapsules were a spherical shape with core‐shell structure and the average size was about 170 nm. DSC and FT‐IR analysis indicated the binary phase change material was encapsulated with polyacrylate shell, and the fusing and crystallizing temperatures and latent heats of nanocapsules were determined as 26.07 °C and 24.85 °C, 56.89 J g^?1 and 54.02 J g^?1 respectively, and the encapsulation efficiency was above 55.09%. In addition, the results of thermoregulating and durability property revealed that the finished cotton fabric had temperature‐regulated and durability properties. POLYM. ENG. SCI., 59:E42–E51, 2019. © 2018 Society of Plastics Engineers     

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     

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     

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 flame retardant phase change materials by microencapsulated paraffin and diethyl ethylphosphonate with poly(methacrylic acid‐co‐ethyl methacrylate) shell

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.     

Tailoring the irreversible thermal expansion of 1,3,5-triamino-2,4,6-trinitrobenzene crystals by bioinspired polydopamine coating

Bioinspired polydopamine (PDA) was selected for the fabrication of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based microcapsules to improve the thermal stability via a facile in situ polymerization of dopamine on the surface of explosive crystals in a weak alkaline aqueous solution. The effects of experimental conditions, including TATB core size, PDA shell content, elevated-temperature hold time, hold temperature, and test stress on the irreversible thermal expansion of TATB crystals, were comprehensively and comparatively studied. After coating, the strain change at each cooling and heating stage in a thermal cycling test from −54 to 74 °C visibly decreased, attributing to the fact that the highly crosslinked and dense PDA shell acted as a rigid pressure vessel to constrain the expansion of energetic crystals. The irreversible expansion strain at room temperature after a 23–113 °C cycle decreased with the increasing of PDA shell thickness. Compared with raw fine grains TATB (FTATB) crystals, FTATB enabled in 1.5 wt % PDA showed a dramatically drop in the irreversible expansion strain at room temperature by 27.7% (from 0.520 to 0.376%). The results demonstrated the excellent ability of PDA to alleviate irreversible thermal expansion of anisotropic energetic crystals. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48695.     

Preparation and characterization of paraffin microcapsules for energy-saving applications

A series of microencapsulated phase-change materials (PCMs) with styrene–divinyl benzene shells composed of an n-octadecane (OD or C₁₈)–n-hexadecane (HD or C₁₆) mixture as the core were synthesized by an emulsion polymerization method. The effects of the core/shell ratio (C/S) and surfactant concentration (C_surf) on the thermal properties and encapsulation ratios of the PCMs were investigated. The chemical structures and morphological properties of the microcapsules were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy analysis, respectively. The characteristic peaks of the paraffin mixtures and shell material located in the FTIR spectrum of the microencapsulated PCMs proved that the encapsulation of the PCM mixture was performed successfully. The thermal properties of the paraffin microcapsules were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis. DSC analysis demonstrated that the microcapsules containing the maximum amount of paraffin mixture (C/S = 2:1) and the minimum C_surf (45 mmol/L) had the highest latent heat value of 88 kJ/kg and a latent heat of temperature of 21.06°C. Moreover, the maximum encapsulation ratio of the paraffin mixture was found to be 56.77%. With respect to the analysis results, the encapsulated binary mixture, which consisted of OD–HD with a poly(styrene-co-divinyl benzene) shell, is a promising material for thermal energy storage applications operating at low temperatures, such as in the thermal control of indoor temperatures and air-conditioning applications in buildings for desirable thermal comfort and energy conservation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47874.     

Preparation and characterization of polyurethane microcapsules containing n‐octadecane with styrene‐maleic anhydride as a surfactant by interfacial polycondensation

A series of polyurethane microcapsules containing a phase change material (PCM) of n‐octadecane was successfully synthesized by an interfacial polymerization in aqueous styrene‐maleic anhydride (SMA) dispersion with diethylene triamine (DETA) as a chain extender reacting with toluene‐2,4‐diisocyanate (TDI). The average diameter of microPCMs is in the range of 5–10 μm under the stirring speed of 3000–4000 rpm. Optical and SEM morphologies of microPCMs had ensured that the shell was regularly fabricated with the influence of SMA. FTIR results confirmed that the shell material was polyurethane and the SMA chains associated on core material reacted with TDI forming a part of shell material. The shell thickness was decreasing in the range of 0.31–0.55 μm with the molar ratio of DETA/TDI from 0.84 to 1.35 and the weight of core material increasing from 40 to 80% (wt %). By controlling the weight ratio of PCM as 40, 50, 60, 70, and 80% in microPCMs, it was found using DSC that the T_m and T_c of microPCMs were in the range of 29.8–31.0^oC and 21.1–22.0°C and an obvious phase change had been achieved nearly the same temperature range of that of PCM. The results from release curves of microPCM samples prepared by 1.4, 1.7, and 2.0 g of SMA indicated the release properties were affected by the amount of the dispersant, which attributed to the emulsion effect and shell polymerization structure. The above results suggest that the shell structure of microPCMs can be controlled and the properties of microPCMs determined by shell will perform proper practical usage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4996–5006, 2006     

Preparation of poly(methyl methacrylate-co-ethylene glycol dimethacrylate-co-glycidyl methacrylate) walled thermochromic microcapsules and their application to cotton fabrics

This study focused on fabrication of the thermochromic microcapsules and their application to the cotton fabric. In this study, thermochromic systems composed of crystal violet lactone, bisphenol A, and 1-tetradecanol were prepared and microencapsulated by emulsion polymerization method in poly(methyl methacrylate-co-ethylene glycol dimethacrylate-co-glycidyl methacrylate) wall. The microcapsules were analyzed by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, differential scanning calorimetry, and thermogravimetric analysis. Their thermoregulating property was tested by T-history test. The results revealed that microcapsules with smooth surfaces, core–shell structured, and spherical shape were successfully produced. The latent heat storage capacity of the microcapsules decreased from 202 J g⁻¹ to 167 J g⁻¹ when their shell/core ratio changed from 0.5/1 to 2/1. Microcapsules were adequately had sufficient thermal resistance to the temperatures they will encounter during their application to textile products and their usage. According to the UV–visible spectroscopy analysis and color measurements, the microcapsules exhibited reversible color change from blue to colorless and vice versa. Besides, the microcapsule impregnated fabric was able to absorb latent heat energy of 21.79 J g⁻¹ at around 35 °C and had cooling effect. According to the colorimetric parameters, the fabric was at blue color at room temperature and became colorless when heated to the temperature above the melting point of thermochromic system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48815.     

Latent curing agent DDM-PMMA microcapsule for epoxy resin

A microcapsule-type latent curing agent is prepared by solvent evaporation method with diaminodiphenylmethane (DDM) as the core material and PMMA as the wall material. The chemical structure, surface morphology, core content, and curing characteristics of as-prepared microcapsule-type curing agent are characterized by FTIR, SEM, TGA, and DSC. The results show that the obtained microcapsules have smooth surface and the core content is about 20 wt %. The one-component adhesive consisting of DDM-PMMA microcapsule and epoxy resin can be cured within 30 min at 130 °C, and the room temperature latent period is more than 30 days. In addition, the internal reasons influencing the core content of microcapsules are analyzed by comparing and analyzing the structural compatibility of three kinds of wall material PMMA, PS, and polyetherimide with DDM. The results show that the core content is affected by the compatibility of wall material and core material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47757.     

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.     

Core–shell particles to toughen epoxy resins. I. Preparation and characterization of core–shell particles

A two-stage, multistep soapless emulsion polymerization was employed to prepare various sizes of reactive core–shell particles (CSPs) with butyl acrylate (BA) as the core and methyl methacrylate (MMA) copolymerizing with various concentrations of glycidyl methacrylate (GMA) as the shell. Ethylene glycol dimethacrylate (EGDMA) was used to crosslink either the core or shell. The number of epoxy groups in a particle of the prepared CSP measured by chemical titration was close to the calculated value based on the assumption that the added GMA participated in the entire polymerization unless it was higher than 29 mol %. Similar results were also found for their solid-state ^13C-NMR spectroscopy. The MMA/GMA copolymerized and EGDMA-crosslinked shell of the CSP had a maximum glass transition temperature (T_g) of 140°C, which was decreased with the content of GMA at a rate of −1°C/mol %. However, the shell without crosslinking had a maximum T_g of 127°C, which decreased at a rate of −0.83°C/mol %. The T_g of the interphasial region between the core and shell was 65°C, which was invariant with the design variables. The T_g of the BA core was −43°C, but it could be increased to −35°C by crosslinking with EGDMA. The T_g values of the core and shell were also invariant with the size of the CSP. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2069–2078, 1998     

Preparation of monosultap-polyurethane microcapsules in an inverse emulsion through interfacial polymerization

In this study, we prepared monosultap microcapsules in an inverse emulsion through interfacial polymerization for the first time. The microcapsules are spherical pellets with intact and smooth shell and have a narrow particle size distribution with an average size of about 2.35 μm. More importantly, our microcapsules have excellent thermal stability with a starting decomposition temperature of 233.1 °C, high encapsulation efficiency of 81.9% as well as long-term slow release of monosultap under different conditions. In addition, the shell of the microcapsules can degrade completely in the natural condition, avoiding the pollution to the environment. It can be believed that our microcapsules will show good service performance if employed in agricultural industry. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48594.     

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.     

Chemically stable polyphenylene ether microcapsules prepared using a facile method for the self‐healing of polymers

Chemically stable polyphenylene ether (PPO) microcapsules (MCs) filled with epoxy resins (PPO‐EP MCs) were prepared using low‐molecular‐weight PPO with vinyl end‐groups as shell wall and epoxy resins as core material using an oil‐in‐water emulsion solvent evaporation method. This method for synthesizing MCs with PPO shell walls is simple, convenient and novel, which can avoid the influence of processing parameters on the chemical stability of the epoxy resin core material. The resulting PPO‐EP MCs exhibit good chemical stability below 255 °C mainly owing to the absence of a polymerization catalyst of the epoxy resins. The initial thermal decomposition temperature of the MCs is about 275 °C. The MCs were embedded in a 4,4′‐bismaleimidodiphenylmethane/O,O′‐diallylbisphenol A (BMI/BA) thermosetting resin system. When processed at high temperature (up to 220 °C), the microencapsulated epoxy resins could be released from the fractured MCs to matrix crack surfaces and bond the crack surfaces. An amount of 8 wt% MCs restored 91 and 112% of the original fracture toughness of the BMI/BA matrix when heated at 220 °C/2 h and 80 °C/1 h + 220 °C/2 h, respectively. The MCs only slightly decreased the thermal property of the matrix. © 2016 Society of Chemical Industry     

Heat‐resistant sustained‐release fragrance microcapsules

In this study, fragrance microcapsules were prepared by a spray‐drying method, in which the osmanthus flower fragrance acted as the core material and gum arabic and maltodextrin acted as shell materials. Scanning electron microscopy images showed that the microcapsules were approximately spherical in shape with a concave surface. Fourier transform infrared spectroscopy was used to prove the formations of the microcapsules. The fragrance retention rate at high temperatures (80–120°C) after a short heating time (30 min) reached 85.20 ± 2.72% and the retention rate after a long heating time (a week) at 60°C reached 95.40 ± 2.88%. The retention rate after 100 days exceeded 90%, and the transdermal release experiments showed that on the surface of the skin, the fragrance in the microcapsules stayed longer than in the pure fragrance oil. These results indicate that the fragrance microcapsules had an excellent aroma‐reserving ability. The results of the release test proved that the transport mechanism of the fragrance microcapsules conformed to the Weibull equation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40053.     

Design of a novel multilayer low-temperature protection composite based on phase change microcapsules

It is necessary to develop a novel low-temperature protective material that ensures the flexibility and warmth of operation in a short time under the low-temperature environment (−30 to −80°C). Hence, a novel multilayer low-temperature protection composite (MPC) was prepared based on phase change microcapsules (microPCMs). MicroPCMs containing n-octadecane with melamine-urea-formaldehyde shell were successfully synthesized through in situ polymerization. Then the microPCMs were finished on the basic fabric's surface (biocomponent spunbond-spunlace nonwoven material) by foam coating and the silicone rubber was covered on the outermost surface. On the basis of scanning electron microscope (SEM) micrographs, microPCMs had a relatively spherical shape and a smooth surface, in which the average particle size was about 42.77 μm. The cross section morphology showed that the MPC was consisted of three layers structure including the base fabric, the microPCMs layer, and the silicone rubber layer. At −50 °C, the low-temperature resistance time of the MPC was 727 s and the power consumption for maintaining a certain temperature for 10 and 20 min of the MPC were 350.86 and 1392.66 J, respectively. Compared with the basic fabric, which has the same thickness as the MPC, the low-temperature resistance time of the MPC was prolonged about 5 min and the power consumption of the MPC for 10 min decreased by 55%, and for 20 minutes decreased by 33%, respectively. The MPC could guarantee the low-temperature protection effect in short time. It could be applied as the potential materials in the area of low-temperature protection. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47534.