Strength Of Microcapsules Research Articles

Self-healing anti-corrosive coating using graphene/organic cross-linked shell isophorone diisocyanate microcapsules

To enhance the anticorrosive performance of coatings in harsh corrosive environments, a graphene/isophorone diisocyanate (IPDI) microcapsule is prepared by in-situ polymerization. The self-healing and anticorrosive performance of coatings based on these microcapsules are studied. The microcapsule with cross-linked shells prepared in this study solves the problems of excessive size and insufficient strength of traditional microcapsules. The addition of microcapsules improves the anticorrosive performance of coatings. The shape of the microcapsules is in the form of round balls, and the average particle size and thickness of the microcapsules are in the range of 17–23 μm and 0.5–3.4 μm, which are conducive to the preparation of the coatings. The average strength of microcapsules is 20.64 MPa and the wrap-around rate reaches 68%. The microcapsules have an initial evaporation temperature of 231.3 °C， the graphene organic cross-linking shell enhances the strength and improves the thermal stability of microcapsules. The electrochemical impedance spectroscopy (EIS) indicates that the |Z|f=0.01 Hz value of the coating with 10 wt% of microcapsule after 168 h of immersion is about 9.4 × 109 Ω cm2, nearly three orders of magnitude higher than that of the coating without microcapsule (6.9 × 106 Ω cm2). Monitoring the artificial scratches of coating using a scanning electron microscope (SEM) for 24 h reveals that the microcapsule repairs the cracks well. It is demonstrated that the incorporation of graphene/IPDI microcapsules improves the anti-corrosive performance of the coating.

Microcapsule Triggering Mechanics in Cementitious Materials: A Modelling and Machine Learning Approach.

Self-healing cementitious materials containing microcapsules filled with healing agents can autonomously seal cracks and restore structural integrity. However, optimising the microcapsule mechanical properties to survive concrete mixing whilst still rupturing at the cracked interface to release the healing agent remains challenging. This study develops an integrated numerical modelling and machine learning approach for tailoring acrylate-based microcapsules for triggering within cementitious matrices. Microfluidics is first utilised to produce microcapsules with systematically varied shell thickness, strength, and cement compatibility. The capsules are characterised and simulated using a continuum damage mechanics model that is able to simulate cracking. A parametric study investigates the key microcapsule and interfacial properties governing shell rupture versus matrix failure. The simulation results are used to train an artificial neural network to rapidly predict the triggering behaviour based on capsule properties. The machine learning model produces design curves relating the microcapsule strength, toughness, and interfacial bond to its propensity for fracture. By combining advanced simulations and data science, the framework connects tailored microcapsule properties to their intended performance in complex cementitious environments for more robust self-healing concrete systems.

Compatibility of high strength silica‐modified microcapsules modified with polydopamine in elastomer substrates

AbstractMicrocapsules with polydopamine composite shell layer were successfully synthesized by functionalizing silica‐modified microcapsules containing isophorone diisocyanate. The components and micromorphology of silica‐modified microcapsules at different reaction periods were studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The structure of different microcapsules was characterized by FTIR, 1H nuclear magnetic resonance and x‐ray photoelectron spectroscopy. The mechanical performances of different microcapsules were analyzed by nanoindentation technique. The compatibility and self‐healing efficiency of different microcapsules with the substrate were also investigated by the tensile tests. The results showed that the density of the silica‐modified microcapsule shell gradually increased and the mechanical performances were enhanced with the silica source. The hardness and elastic modulus of silica‐modified microcapsules in suitable core fraction (76.5 wt%) were 139.9 MPa and 2.2 GPa, which are 2.3 times and 4.8 times higher than those of untreated microcapsules, respectively. The functionalized modified microcapsules had excellent compatibility with the elastomeric substrate (PU‐PPG2000). At the same time, the self‐healing efficiency of the functionalized modified microcapsules in PU‐PPG2000 was 69.8%, which was 48.9% higher than that of the untreated microcapsules prepared under the same conditions. Silicon modification improved the density of microcapsules, enhancing their mechanical strength. At the same time, functionalization modification improved the interfacial bonding strength of microcapsules, further improving the compatibility with the polymer matrix.Highlights Microcapsules with different silicon sources are characterized. Microcapsules are functionalized with polydopamine. Individual microcapsules are tested for mechanical strength by nanoindentation. The compatibility of the functionalized microcapsules is excellent. The self‐healing efficiency of modified microcapsules is greater than 70%.

Improving the mechanical performance of phase change microcapsule/epoxy composites via alternately enhancing interface bonding and strength of microcapsules

Microcapsules containing phase change materials (MPCMs) can be integrated with polymeric matrices to develop intelligent thermoregulating composites for applications in temperature management and thermal energy storage. However, the mechanical properties of such composites can be severely compromised due to the weak interfacial adhesion and the poor microcapsule rupture strength. This paper aims to investigate the failure mode of microcapsule/epoxy composites and present corresponding implementable methods to improve their strength. The MPCMs/epoxy composite primarily fails due to poor microcapsule-matrix interface debonding resulting from the poor compatibility between MPCMs and epoxy resin. A silane coupling agent (EPTMS) was employed to modify the surface of MPCMs, forming E-MPCMs, and created a crosslinked interface network during the epoxy curing process. The tensile strength of composite containing 20 wt% E-MPCMs has been improved by 23.55 % while the failure mode switching to microcapsule rupture. Furthermore, the microcapsule shell enhanced by TiO2 nano-reinforcements achieves a 105.20 % improvement in microcapsule rupture strength. The incorporation of EPTMS modified TiO2-MF hybrid microcapsules (ET-MPCMs) resulted in a significant increase of 33.79 % in the tensile strength of ET-MPCMs/epoxy composite with the failure mode changing to microcapsule-matrix interface debonding again. The strategy of alternately enhancing subset properties derived from the competition failure mode of the composite opens new perspectives for the preparation of high-performance multifunctional composites.

Experimental and numerical research on healing performance of reinforced microcapsule-based self-healing polymers using nanoparticles

The effect of enhancing multicore microcapsules with various nanoparticles on the healing efficiency of microcapsule-based self-healing polymers was investigated in this study. The incorporated polymers with enhanced microcapsules by MWCNT, nanoclay, and nanosilica were fabricated. Three volume fractions (VFs) of microcapsules, including 5, 7.5, and 10% were added to the epoxy matrix. The maximum tensile stresses of the virgin, damaged by controlled low velocity impact test, and healed specimens were obtained to calculate the healing efficiencies of fabricated self-healing polymers. Also, a multi-scale FE modeling was promoted using RVEs generation and ABAQUS-Explicit solver attached with VUSDFLD subroutines to predict the healing efficiencies. The results indicated that by increasing the VF of microcapsules, the healing efficiencies of specimens were increased. Increasing the VF of the microcapsules could increase the probability of hitting induced cracks due to the LVI test with microcapsules. Thus, further spreading of healing agents into the propagated cracks would increase the healing efficiency of specimens containing higher VF of microcapsules. Also, increasing the strength of microcapsules reduced the healing efficiency of specimens. For instance, in the specimens containing 10% VF of enhanced microcapsules with MWCNT, the healing efficiency was 45.90%, while it was 50.41% for enhanced microcapsules with nanosilica. Increasing the mechanical properties of microcapsules could decrease the probability of rupturing damaged microcapsules, which reduced the healing efficiency of these specimens. Finally, the predicted healing efficiency of simulated RVEs had good accuracy, indicating the reliability of introduced multi-scale FEM.

Enhanced mechanical properties of epoxy composites embedded with MF/TiO2 hybrid shell microcapsules containing n-octadecane

Microencapsulated phase change materials (MPCMs) are often mixed with matrix materials to form phase change composites for energy storage. Typically, MPCMs are easily debonded from the matrix or ruptured, thereby weakening the mechanical properties of composites. This paper aims to simultaneously improve the rupture strength of microcapsules and the bonding strength between microcapsules and matrix to enhance the mechanical properties of composites. The titanium dioxide (TiO2) nanoparticles modified by a silane coupling agent (KH560) were doped into the melamine formaldehyde (MF) shell, forming n-octadecane@MF/TiO2 hybrid shell MPCMs (HS-MPCMs). The doping of modified TiO2 nanoparticles reduced supercooling and improved the thermal stability of microcapsules. Compared with MF microcapsules, the rupture strength of HS-MPCMs was increased by an average of 30.4%. The modified TiO2 nanoparticles also built covalent bonds between microcapsule shell and matrix, which led to better microcapsule/epoxy interface bonding. Thus, the HS-MPCMs/epoxy composites performed higher tensile strength than the unmodified composites. Specifically, the tensile strength of composites was improved by an average of 17.2% at the microcapsule content of 10 wt.% with the aid of the MF/TiO2 hybrid shell. The reinforced MPCMs/epoxy composites are expected to be used as anti-icing coatings in the aerospace field.

Preparation and Performance of Dual-functional Magnetic Phase-change Microcapsules.

The fabrication of desired anti-magnetic materials for irradiation shielding remains a challenge to date. In this work, a new type of dual-functional magnetic shielding phase change microcapsules with paraffin as the core, melamine-formaldehyde (MF) resin as the shell and doped with magnetic particles in the shell were successfully prepared by in situ polymerization. The magnetic particles were dispersed in the shell layer by coating a hydrophilic emulsifier on the surface. These microcapsules were specifically applied to the field of magnetic shielding by the screen printing method. The effect of magnetic particles on the performance of phase-change microcapsules was examined by differential scanning calorimetry and thermogravimetric analyses. The magnetic type and magnetic strength of the microcapsules were studied by the vibrating sample magnetometer. Moreover, the effects of different magnetic particles (Fe3 O4 , CrO2 ) on the performance of phase change microcapsules and the magnetic strength of microcapsules were compared. The results showed that these two kinds of magnetic particles can greatly improve the phase change latent heat, thermal stability, and thermal conductivity of the microcapsules. Finally, the great magnetic shielding role of these microcapsules was demonstrated in both static and pulsed magnetic fields through the screen printing of magnetic shielding ink on wallpaper. Incorporating 0.5 g Fe3 O4 inside of microcapsules, specifically, the magnetic intensity was effectively reduced by ∼250 Oe within a short distance in the static field. We expect that these magnetic microcapsules hold great potential for the shielding of irradiations via the screen printing on various substrates.

Detailed experimental and theoretical investigation of the thermomechanical properties of epoxy composites containing paraffin microcapsules for thermal management

AbstractMicroencapsulated phase change materials (PCMs) are being increasingly employed as functional fillers in polymer matrices for thermal management. Therefore, the effect of PCM microcapsules on the rheological, microstructural, thermal and mechanical properties of the host polymer matrices must be understood. This work concerned the preparation of epoxy polymers filled with PCM microcapsules (MC) in various concentrations and their subsequent characterization. The MC phase increases the viscosity of epoxy before curing, thereby reducing castability and hindering elimination of air bubbles. The latter was reflected in an increase in porosity for highly filled compositions, as elucidated by density measurements and microscopic investigation. SEM micrographs showed that the adhesion between the capsule shell and the epoxy matrix was not optimal. The interfacial weakness and the intrinsic low stiffness and strength of MC caused a reduction in mechanical properties, as evidenced by the Nicolais‐Narkis and Pukanszky models. On the other hand, at zero or low deformation levels, the interface presents no gaps and is able to transfer load and heat, as demonstrated by the data of elastic modulus, modeled with the Halpin‐Tsai and Lewis‐Nielsen models, and those of thermal conductivity, in excellent agreement with the Pal model. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

Preparation and Characterization of Microcapsules Containing Soybean Oil and Their Application in Self-Healing Anticorrosive Coatings

ABSTRACTSynthetic self-healing materials are a new prototype in polymeric coatings. In the present investigation, soybean oil along with drier was encapsulated in urea–formaldehyde (UF) microcapsules, which were successfully prepared by in situ polymerization and their self-healing ability, the corrosion resistance, gloss, and adhesion strength of microcapsules were studied. The synthesized microcapsules were characterized by Fourier transform infrared spectrometer for identification of separated core and shell materials and their surface morphology was studied by scanning electron microscope. The particle size was checked under optical microscope and confirmed with particle size analyzer. Effectiveness of soybean oil-filled microcapsules was investigated for healing of cracks generated in anticorrosive coatings. Cracks in paint coatings were found to be healed when soybean oil was released from microcapsules under simulated mechanical action and the corrosion resistance of healed area was evaluated by immersion study.

Protection mechanism of alginate microcapsules with different mechanical strength for Lactobacillus plantarum ST-III

Alginate microcapsule is widely used to encapsulate and protect lactic acid bacteria (LAB). This study aims to design microcapsules with different mechanical strength and clarify their protecting mechanism for Lactobacillus plantarum ST-III under simulated digestive conditions through physical and physiological analysis. By controlling viscosity and gelling ability of alginate solution, a series of microcapsules with the same particle size (ca. 400 μm) and varying mechanical strength (5.4–51.9 N) were prepared. Cell survivals in simulated gastric juice (SGJ) and bile salts (BS) were found to be positively correlated with the mechanical strength of microcapsules. Diffusion experiments using different probes showed that the permeability coefficients of the microcapsules decreased with increasing mechanical strength. Moreover, membrane integrity and membrane fluidity of encapsulated LAB in SGJ were reduced to a less extent and tended to maintain at normal physiological values, with increasing mechanical strength. In contrast, cell membrane integrity was much more reduced (<4.0%) and membrane fluidity was markedly augmented in BS, regardless of the mechanical strength of microcapsules, indicating seriously damaged cells with abnormal physiological properties. These physical and physiological indexes together manifested the protection mechanism of alginate microcapsules with different mechanical strength for LAB.

Determination of the Mechanical Strength of Microcapsules.

The promise of pancreatic islet transplantation is hindered by organ shortage, and the need for immunosuppression of transplant recipient in order to prevent rejection. Alginate microencapsulation can overcome these hurdles; however further optimization of this technique is required. Among the critical factors to be optimized is the durability of alginate microcapsules, which can be determined by their mechanical strength tests. Here we describe several simple and reliable methods to assist in assessing the mechanical strength of alginate beads.

Encapsulation of volatiles by homogenized partially-cross linked alginates

Cross-linked calcium alginate gels are too viscous to be efficaciously incorporated into spray dried formulations. Thus, viscosity reduction is essential to ensure the processability of calcium alginate gels to be sprayed. Viscosity reduction by high pressure homogenization can open new formulation possibilities. Presently, testing of microcapsule integrity is also limited because either single particle tests neglect collective particle behaviours in bulk or bulk testing methods are often associated with single compressions which may not fully characterize individual particle strengths. The aim of this study was sub-divided into three objectives. First objective was to evaluate the impact of high pressure homogenization on gel viscosity. Second objective was to explore the use of the homogenized gels with modified starch for microencapsulation by spray drying. The final objective was to develop a stamping system as microcapsule strength tester that can assess microcapsules in bulk and evaluate the impact of multiple compressions. Collectively, this study would lead towards developing a pressure-activated patch of microcapsules with encapsulated volatiles and the method to assess the patch efficacy. The alginate gels largely experienced an exponential decay in viscosity when homogenized. Furthermore, the homogenized gels were successfully incorporated in spray drying formulations for microencapsulation. The custom-designed microcapsule strength tester was successfully used and shown to possess the required sensitivity to discern batches of microcapsules containing volatiles to have different release profiles. Addition of homogenized gels strengthened the microcapsules only at high wall to core ratios with low mass-load alginate gels. High mass-load gels weaken the microcapsules, exhibiting a higher release at low stamping pressures and wrinkling on the microcapsules surface.

Microencapsulation of Lactobacillus acidophilus CGMCC1.2686: Correlation Between Bacteria Survivability and Physical Properties of Microcapsules

Correlation between lactic acid bacteria (LAB) survivability and physical properties of microcapsules is critical to revealing the protecting mechanism of microcapsules for LAB. In this paper, five formulae of microcapsules with increasing mechanical strength were chosen to encapsulate Lactobacillus acidophilus CGMCC1.2686 using the method of emulsification/internal gelation. Morphological and size characteristics showed that particle diameter of the five LAB microcapsules ranged from 263.4 to 404.6 μm, with a span factor from 0.87 to 1.12. The increased mechanical strength of the microcapsules was accompanied with increased viscoelasticity and structural compactness as observed by scanning electron microscopy. Most of the microspheres shrinked in simulated gastric juice (SGJ), whilst swelling in bile salts solution (BS). Regression analysis showed that cell viability in SGJ was positively correlated with the mechanical strength of microcapsules. However, increasing mechanical strength did not significantly improve cell survival in BS.

Release of tissue inhibitor of metalloproteinase-2 from alginate microcapsule encapsulating genetically engineered cells

BackgroundIn this study, 293T cells were genetically engineered to secrete tissue inhibitor of metalloproteinase-2 (TIMP2) and encapsulated into alginate microcapsules to continuously release TIMP2 protein.MethodsThe anti-invasive potential of the microcapsules was studied in vitro using brain tumor cells. The TIMP2 gene was transfected to 293T cells, and genetically engineered 293TIMP2 cells were encapsulated into alginate microcapsules. Release of TIMP2 protein was detected with Western blot analysis and the anti-invasive potential against U87MG cells was tested using gelatin zymography and a Matrigel assay.ResultsCell viability within the alginate microcapsules was maintained at a cell density of 5 × 106. Because polycationic polymers are helpful for maintaining the mechanical strength of microcapsules with good cell viability, the alginate microcapsules were reinforced with chitosan (0.1% w/v). Expression of TIMP2 protein in cell lysates and secretion of TIMP2 into the conditioned medium was confirmed by Western blot analysis. Alginate microcapsules encapsulating 293TIMP2 cells released TIMP2 protein into the medium efficiently, where the TIMP2 protein participated in degradation of the matrix metalloproteinase-2 enzyme and inhibited invasion of U87MG cells.ConclusionAlginate microcapsules encapsulating 293TIMP2 cells are promising candidates for anti-invasive treatment of glioma.

Microencapsulation of a PCM through membrane emulsification and nanocompression-based determination of microcapsule strength

Microencapsulating a phase-change material (PCM) has become a prominent method of creating a stable environment in which the PCM can undergo its phase change without affecting the environment in which it is used. The method of encapsulation used in this study takes advantage of a new technology known as membrane emulsification and suspension polymerization. This study investigates the encapsulation of the paraffin wax RT21® in a poly(methyl methacrylate) shell, which could be used to increase the thermal mass of a building. The objectives of the study are: (1) to encapsulate RT21® through the use of membrane emulsification and (2) to test the mechanical properties of the microcapsules under nanocompression. Membrane emulsification was carried out using Shirasu porous glass hydrophilic membranes of pore sizes 10, 10.2, and 20 μm. Polymerization was conducted in a batch reactor with methyl methacrylate as the monomer in the temperature range 70–90 °C. The thermal properties (the latent heat of melting and melting temperature) of the microcapsules were tested using a differential scanning calorimeter. Particle size analysis was conducted to determine the average size distribution of the microcapsules produced. Membranes with pore sizes of 10, 10.2, and 20 μm produced microcapsules with average diameters of 22.40 ± 1.47, 25.38 ± 0.80, and 37.50 ± 1.69 μm, and average latent heats of 113.91 ± 12, 116.69 ± 1.40, and 109.89 ± 8.69 J/g, respectively. In order to determine the mechanical properties of these microcapsules, a modified nanoindentation compression technique was used to test the bursting force for individual microcapsules.

Investigation of alginate–ϵ‐poly‐L‐lysine microcapsules for cell microencapsulation

Cell microencapsulation is a promising approach for cell implantation, cell-based gene therapy, and large-scale cell culture. The well-studied α-AP (alginate-α-poly-L-lysine) microcapsules have been restricted to large-scale cell-culture and clinical applications because of high costs and cytotoxic effects in some cases. This study used ε-poly-L-lysine (ε-PLL), a high-biocompatible and low-cost food additives produced by fermentation, to prepare ε-AP (alginate-ε-PLL) microcapsules with various thickness membranes and swelling behaviors. ε-AP microcapsules were permeable to BSA, a standard protein of culture medium. ε-AP-microencapsulated Chinese hamster ovary (CHO) cells proliferated with culture time; no obvious difference with α-AP-microencapsulated CHO cells during the early 19 days. Whereas ε-AP-microencapsulated CHO cells kept higher viability (OD = 0.646 ± 0.012) on the 22nd day and microcapsule strength (integrity rate of 88%) on the 24th day than that of α-AP microcapsules (OD = 0.558 ± 0.025, integrity rate of 80%). ε-AP (alginate-ε-PLL) microcapsules exhibited more superior properties and could lower the costs to broaden the applications of microencapsulation technology.

Study of the effect of membrane thickness on microcapsule strength, permeability, and cell proliferation

Cell microencapsulation is one of the promising strategies for in vitro production of proteins or in vivo delivery of therapeutic products. Membrane thickness controls microcapsule strength and permeability, which may in return affect cell growth and metabolism. In this study, the strength, permeability, and encapsulated Chinese hamster ovary cell proliferation and metabolism of four groups of microcapsules with different membrane thicknesses were investigated. It was found that increasing membrane thickness increases microcapsule strength, whereas decreases membrane permeability. During the first 6 days, cells within microcapsules with 10 μm thickness membrane proliferated fast and could reach a cell density of 1.9 × 10(7) cells/mL microcapsule with 92% cell density. A cell density of 5.5 × 10(7) cells/mL microcapsule with >85% cell density was achieved within microcapsules with 15 μm membrane thickness and these microcapsules kept over 88% integrity ratio after 11 days, which was much higher than that of microcapsules with 10 μm membrane thickness. Membrane with more than 20 μm thickness was not suited for encapsulated cell culture owing to low-protein diffusion rate. These results indicated that cells survived shortly within the thinnest membrane thickness. There was a specific membrane thickness more suitable for cell growth for a long-time culture. These findings will be useful for preparing microcapsules with the desired membrane thickness for microencapsulated cell culture dependent on various purposes.

Abstract 498: Anti-invasive potential of alginate microcapsule encapsulating TIMP 2-engineered cells against malignant glioma cells

Abstract Objectives. 293T was genetically modified to secrete tissue inhibitor of metalloproteinase-2 (TIMP-2) (abbreviated as 293TIMP2 cells) and 293TIMP2 cells were encapsulated into alginate microcapsules to produce TIMP-2 protien continuously. Since TIMP-2 is known to inhibit matrix metalloproteinase-2 (MMP-2) expression of tumor cells, it could be inhibit invasion of tumor cells through extracellular matrix. The anti-invasive potential of the microcapsules was studied in vitro against U87MG glioma cells. Experimental. The TIMP-2 gene was transfected to 293T cells and the genetically engineered 293TIMP2 cells were encapsulted into alginate microcapsules. The released TIMP-2 protein was examined with Western blot analysis and the anti-invasive potential against U86MG glioma cells was tested with gelatin zymography for matrix metalloproteinase-2 (MMP-2) and a Matrigel assay for invasion. Results. Cell viability within the alginate microcapsules was properly maintained at a cell density of 5×106 cell density. Since polycationic polymers are helpful to maintain mechanical strength of microcapsules with good cell viability, alginate microcapsules were reinforced with chitosan (0.1 % wt/vol). Expression of TIMP-2 protein in cell lysate and the secreted TIMP-2 into conditioned media were confirmed with Western blot analysis. Alginate microcapsules encapsulating 293TIMP2 cells properly released TIMP-2 protein into the medium and the released TIMP-2 protein was effective in inhibiting MMP-2 expression and invasion of U87MG glioma cells. Conclusion. These results indicated that alginate microcapsules encapsulating 293TIMP2 cells are superior candidates for anti-invasive therapy of glioma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 498. doi:1538-7445.AM2012-498

Preparation and properties of poly(urea–formaldehyde) microcapsules filled with epoxy resins

The poly(urea–formaldehyde) (PUF) microcapsules filled with epoxy resins have potential for self-healing or toughening polymeric composites. A series of PUF microcapsules containing epoxy resins were synthesized by selecting different process parameters including surfactant type, surfactant concentration, adjusting time for pH value and heating rate. The effects of process parameters on the size and surface morphology of microcapsules were discussed. The storage stability, solvent resistance and the mechanical strength of microcapsules were investigated. The morphology of microcapsules was observed using scanning electron microscopy (SEM) and optical microscopy (OM). The results indicate that the formation of microcapsules is affected by the surfactant type. The size of microcapsules can be controlled by the surfactant concentration. The surface morphology of microcapsules can be adjusted by the surfactant concentration, the adjusting time for pH and the heating rate. The microcapsules prepared by using surfactant sodium dodecylbenzene sulfonate (SDBS) show good storage stability, excellent solvent resistance and appropriate mechanical strength.

Preparation of PCM microcapsules by using oil absorbable polymer particles

We attempted to prepare microcapsules by absorbing n-pentadecane as the phase change material (PCM) and methyl methacrylate (MMA) as the shell material into oil absorbable polymer particles. We could prepare the microcapsules containing PCM with the polymethyl methacrylate (PMMA) shell. In the experiment, the volume of methyl methacrylate monomer and the soaking time for oil absorbable polymer particles to soak into MMA were changed stepwise. With the increase in the volume of MMA absorbed, the diameters and mechanical strength of microcapsules were increased. Furthermore, it was found that the amount of PCM leaking from the microcapsules was decreased with the volume of MMA absorbed.