Effect Of Microcapsules Research Articles

Enhancement of oxidative stability of camelina oil via Alyssum homolocarpum seed gum/sodium alginate–based microcapsules loaded with Echinacea purpurea (L.) extract

Alyssum homolocarpum seed gum (AHSG) and sodium alginate (SA) were utilized as wall materials for the microencapsulation of Echinacea purpurea extract via spray drying. Furthermore, effect of microcapsules on the oxidative stability of camelina oil was assessed over a 30-day storage period. The results showed that with an increase in AHSG concentration, the particle size, polydispersity index, and zeta potential of emulsions decreased, while their viscosity, and stability increased. Microcapsules prepared with AHSG alone exhibited the highest encapsulation efficiency (90.70 %), loading efficiency (40.70 %), and water solubility (88.47 %), but the lowest moisture content (1.45 %), water activity (0.31), wettability (198 s), and hygroscopicity (13.50 g/100 g). Scanning electron microscopy analysis revealed a spherical and smooth surface for AHSG alone-based microcapsules. Fourier transform infrared spectroscopy analysis indicated that certain chemical interactions occurred between the E. purpurea extract and wall materials. By incorporating AHSG/SA-based microcapsules containing E. purpurea extract into camelina oil, the peroxide value (increasing from 1.79 to 5.12 meq∙O2/kg) and anisidine value (increasing from 1.63 to 7.09) were maintained during the 30-day storage period. In conclusion, the microcapsules prepared with AHSG alone showed significant potential for encapsulating E. purpurea extract and subsequently enhancing oxidative stability of camelina oil, comparable to TBHQ.

Recycling of waste edible oil derivatives as phase change materials for building energy conservation

A novel phase change microcapsule with waste edible oil derivatives core shelled by silica was prepared for building energy conservation. The substance composition, phase change parameters, and functional group of the derivatives were characterized. The phase change temperature, phase change enthalpy, and particle size of phase change microcapsules were determined. The effect of microcapsules on foamed concrete was evaluated, including mechanical and thermal properties. The results indicate that the waste edible oil derivatives with a phase change temperature of around 18 °C and a phase change enthalpy of about 140J/g are mainly composed of 73.8% methyl palmitate and 16.2% methyl oleate. The phase change temperature and enthalpy of the microcapsules with a 1:1 shell-to-core ratio are 20 °C and 73J/g, respectively. Additionally, the Dv (50) and Dv (90) of the microcapsules are 139 μm and 380 μm, respectively. Furthermore, the recommended dosage of microcapsules in foamed concrete should not exceed 6.0 wt% considering the mechanical properties of foamed concrete. During the heating process, the temperature of foamed concrete containing 6.0 wt% microcapsules is up to 4.3 °C lower than that of conventional concrete. On the other hand, the cooling rate of foamed concrete containing 6.0 wt% microcapsules is 51.5% lower than that of conventional concrete. This work realizes both building energy conservation and resource utilization of waste edible oil.

Effect of microcapsules’ mechanical stability on the encapsulated cells’ behavior

Stem cell microencapsulation offers immunoprotection, utilizing natural polymers such as sodium alginate (SA), chitosan, and derivatives such as trimethyl chitosan (TMC). Additive minerals improve microcapsule properties and cell differentiation. Layering increases mechanical strength and shields cells from the host’s immune system. This study explores the impact of incorporating nano-hydroxyapatite (nHA) and graphene oxide (GO) into the three-layer alginate–TMC–alginate microcapsules housing human adipose mesenchymal stem cells (haMSCs). The experimental design focused on optimizing the mechanical stability, with the ideal GO and nHA contents identified as 0.81% and 34% w/w, respectively. Rheological analysis revealed enhanced mechanical consistency, evidenced by higher storage modulus and lower loss factor in the optimized sample. Viability of the microencapsulated haMSCs, assessed through acridine orange/propidium iodide staining and MTT assays, affirmed the nontoxic nature of the microcapsules. Osteogenic potential was evaluated via alkaline phosphatase (ALP) activity measurement and immunocytochemistry staining. Microcapsules containing nHA and GO exhibited significantly elevated ALP activity, underscoring the pivotal role of these additives in enhancing mesenchymal stem cell differentiation. The highest osteocalcin deposition occurred in the optimized and SA/nHA 40% w/w groups in the differentiation medium. This comprehensive investigation highlights the potential of three-layer microcapsules with nHA and GO for bone tissue engineering applications.

Engineering properties of microcapsules self-healing geopolymer cutoff wall backfill under dry-wet cycles

Vertical cutoff wall has been employed for decades to control groundwater flow and subsurface contaminant transport. Environmental stress fluctuations induced by alternating dry and wet conditions impair the permeability and durability of the cutoff wall, leading to the dispersion of contaminants. The objective of this study is to incorporate self-healing microcapsules into existing geopolymer cutoff wall backfill (GCWB) to form self-healing geopolymer cutoff wall backfill (SHGCWB) that hold promise for better durability and performance. The in-situ polymerization method was used to develop single-walled and double-walled microcapsules. The microcapsules use sodium silicate as the healing agent encapsulated in single-walled polyurethane (PU) and double-walled polyurethane/melamine-formaldehyde (PU/MF) microcapsules. The effect of microcapsules on the unconfined compressive strength (UCS) and hydraulic conductivity of SHGCWB were elaborated. The durability and hydraulic conductivity variation of SHGCWB in dry-wet cycle was thoroughly investigated by Scanning Electron Microscopy (SEM) test for understanding the self-healing mechanism. The overall performance demonstrated the significant potential of the use microcapsules as a self-healing approach for cutoff walls.

Feasibility of micro-organisms in soil bioremediation and dust control

Detrimental impacts of dust caused by mine tailings have yielded to several studies on the efficiency of different soil stabilizers. Bacterial stabilization has been recognized as a reality within recent decades, where bacteria could get adhesion to the grains and stabilize the soil particles. However, these bacteria are prone to be destroyed while exposed to the normal environmental conditions. In this study, the effects of microcapsules containing two types of bacterial freeze-dried spores (B.Subtilis Natto LMG 19457 and B.ESH) have been investigated on the mine tailing stability in terms of two parts. The first part of the study is dedicated to the fabrication of microcapsules within the two bacteria and identification of the characteristics of these microcapsules to set the time of microcapsules break and release in the soil. The urea-formaldehyde microcapsules containing tung oil were synthesized using microencapsulation method and at the following, the bacterial spores of B.Subtilis Natto LMG 19457 and B.ESH which had the high durability and the capability to grow in the silicon oil, were added to the microcapsules. The microcapsules effect on MT specimens and the viability of encapsulated spores were determined. The characteristics of the capsules were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermo-gravimetric thermal analysis (TGA). In the second part, wind tunnel tests were conducted to study the effects of microorganism stabilizers on mine tailings. The results indicated that the dust erosion reduced from 16% - using water as a stabilizer- to the 0.2% while using microcapsules containing B.Subtilis Natto LMG 19457 and 0.8% while using microcapsules containing ESH. The results showed the high efficiency of microcapsules containing bacteria in stabilizing the MTs. This phenomenon was proved by SEM imaging in which the voids were bounded significantly while using the bacteria.

Preparation and performance study of OPC-MF-PEG microcapsules based on strong antioxidant groups against spontaneous coal combustion

In order to solve the problem of spontaneous combustion of coal in the air-mining area, flame-retardant microcapsules were prepared by in-situ polymerization. OPC-MF-PEG flame-retardant microcapsules were prepared by selecting proanthocyanidin (OPC) as the core material of the microcapsules, polyethylene glycol-modified Melamine resin (hereinafter referred to as modified resin) as the shell. The microcapsules were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), stability analysis experiments, thermogravimetric analyzer (TG), and other experiments in terms of their surface morphology, dispersion, encapsulation, pyrolysis, and other properties. On this basis, the microcapsules were mechanically mixed with coal samples to prepare chemically inhibited coal samples. The effects of microcapsules with different core-to-wall ratios on the spontaneous combustion characteristics of coal were investigated by TG experiments. The results showed that the flame retardant effect was best when the core-to-wall ratio was 3:1. According to the analysis of the combustion experiment results, the CO concentration of the coal samples treated with microcapsules was reduced by 57.5% and 22.5% compared with that of the pure coal and OPC-treated coal samples.

Preparation and characterization of starch/PBAT film containing hydroxypropyl-β-cyclodextrin/ethyl lauroyl arginate/cinnamon essential oil microcapsules and its application in the preservation of strawberry

Cinnamon essential oil (CEO) was emulsified by hydroxypropyl-β-cyclodextrin/ ethyl lauroyl arginate (HPCD/LAE) complex to make nanoemulsions, which were then incorporated into maltodextrin (MD) to prepare HPCD/LAE/CEO/MD microcapsules by spray drying. The starch/polybutylene adipate terephthalate (starch/PBAT, SP) based extrusion-blowing films containing above microcapsules were developed and used as packaging materials for strawberry preservation. The morphology, encapsulation efficiency, thermal and antibacterial properties of microcapsules with different formulations were investigated. The effects of microcapsules on the physicochemical and antimicrobial properties of SP films were evaluated. When the formula was 4 % HPCD/LAE-3% CEO-10% MD (HL-3C-MD), the microcapsule had the smallest particle size (3.3 μm), the highest encapsulation efficiency (84.51 %) of CEO and the best antibacterial effect. The mechanical and antimicrobial properties of the SP film were enhanced while the water vapor transmittance and oxygen permeability decreased with the incorporation of HL-3C-MD microcapsules. The films effectively reduced the weight loss rate (49.03 %), decay rate (40.59 %) and the total number of colonies (2.474 log CFU/g) and molds (2.936 log CFU/g), thus extending the shelf life of strawberries. This study revealed that the developed SP films containing HPCD/LAE/CEO microcapsules had potential applications in degradable bioactive food packaging materials.

Effects of microcapsules with turmeric and green propolis supplementation on inflammatory markers in hemodialysis patients

Effects of microcapsules with turmeric and green propolis supplementation on inflammatory markers in hemodialysis patients

A Novel Oral Drugs Delivery System for Borneol Based on HiCap®100 and Maltodextrin: Preparation, Characterization, and the Investigation as an Intestinal Absorption Enhancer.

The objective of this study was to create a new method for delivering oral borneol (BN) drug that would improve stability. This was accomplished through microencapsulation using HiCap®100 and maltodextrin (MD), resulting in HiCap®100/MD/BN microcapsules (MCs). The HiCap®100/MD/BN MCs were evaluated in terms of encapsulation efficiency (EE%), drug loading (DL%), morphological observations, particle size distribution, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermal analysis, drug degradation rate studies, and in vitro release behavior. The effect of MCs on intestinal permeability in a rat model was assessed using the model drug "florfenicol" (FF) in single-pass intestinal perfusion (SPIP) study. The relationship between MCs and P-glycoprotein (P-gp) was further investigated in comparison with verapamil (Ver). The irritation of MCs was assessed by histological analysis. The MCs in a spherical structure with micron-scale dimensions were obtained. The EE% and DL% were (86.71 ± 0.96)% and (6.03 ± 0.32)%, respectively. MCs played a significantly protective role in drug degradation rate studies. In vitro release studies indicated that the release behavior of MCs was significantly better than BN at the three-release media, and the cumulative release rate exceeded 90% in 15 min. The SPIP studies showed that MCs significantly enhanced the absorption of FF in rats. Compared with Ver, MCs were not promoted by a single inhibition of P-gp. Hematoxylin-eosin (HE)-stained images showed that MCs had no obvious irritation and toxic effects on the intestines of rats. Thus, the preparation of HiCap®100/MD/BN MCs improves the stability of BN, which has certain scientific value for the development and application of BN, and provides unique perspectives for future BN-related researches.

Effect of Microcapsules on Mechanical, Optical, Self-Healing and Electromagnetic Wave Absorption in Waterborne Wood Paint Coatings

A mixture of multiwalled carbon nanotubes (CNTs) and carbonyl iron powder (Iron(0) pentacarbonyl, CIP) was used as a core material, and a melamine-formaldehyde resin was used as a wall material to prepare CIP/CNTs microcapsules. A core-wall ratio, content of CNTs in the core material, stirring speed, and reaction time were carried out to explore the most significant factor affecting the coverage rate and yield of microcapsules. The most important factor affecting the preparation of CIP/CNTs microcapsules was the content of CNTs in the core material. The optimized CIP/CNTs microcapsules were mixed with shellac microcapsules, and the optimal ratio was explored by analyzing their optical, mechanical, and electromagnetic wave absorption properties in order to prepare coatings with superior performance. The lower the addition amount of CIP/CNTs microcapsules, the lower the effect on the color difference of the coating. The gloss and adhesion of waterborne wood paint coatings decreased with increasing CIP/CNTs microcapsule addition. The hardness, impact resistance and tensile properties of the coatings showed a tendency of increasing and then decreasing with the addition of CIP/CNTs microcapsules. The surface roughness of the coating basically tended to increase with the increase of CIP/CNTs microcapsule content. When the content of added CNTs in the core material was 3.0% and the content of microcapsules was 9.0%, the coating had the highest elongation at break of 12.4% and the highest repair rate of 34.3%, respectively. The mixed shellac microcapsules and CIP/CNTs microcapsules achieved a theoretical minimum reflection loss of −13.52 dB at 16.2 GHz, and the electromagnetic wave absorption band of less than −5 dB was 15.3 GHz–18.0 GHz. The results provide technical references for the preparation of self-healing composite electromagnetic wave absorption coatings on wood substrates.

Effect of microcapsules on the self-repairing ability of limestone calcined clay cement (LC3) mortar at different temperatures

The fundamental principle of sustainable civil engineering revolves around minimizing energy and resource consumption throughout the entire life cycle of a structure, including raw material production, construction, and maintenance. To achieve this, efficient utilization of raw materials is crucial. LC3, a novel low carbon cementitious material, offers sustainability advantages. In this paper, LC3 mortar was prepared by incorporating limestone, calcined clay and gypsum as supplementary cementitious materials, thereby replacing 50% of ordinary Portland cement (OPC). Additionally, microcapsules, comprising 4% of the total mass of cementitious materials, were introduced. This reduction in OPC content not only decreases energy consumption and CO2 emissions during cement preparation but also capitalizes on the self-repairing ability of microcapsules to mend microcracks that occur within the cement-based material during its service life. Consequently, the durability of cement-based materials is enhanced. To evaluate the effects of self-repairing on mechanical properties, permeability, and maximum amplitude at different temperatures, a comparison was made between OPC mortars and LC3 mortars. Furthermore, the self-repairing ability of surface cracks in microencapsulated mortar was assessed. The findings demonstrate that the mechanical and permeability properties of LC3 mortar (designated as CA2) exhibit no significant deviation from those of OPC mortar (designated as CA0). Moreover, under the same conditions, LC3 mortar containing microcapsules (designated as CA3) displays superior self-repairing ability compared to OPC mortar containing microcapsules (designated as CA1). Additionally, the self-repairing characteristics of microcapsules in LC3 mortar improve with increasing temperature. The self-repair process involving epoxy resin (repairing agent) and 2-ethyl-4-methylimidazole (curing agent) follows a quasi-second-order reaction kinetic model. Surface cracks with an initial width exceeding 0.4 mm in CA3 were entirely repaired within a 72-hour period.

The Application of Self-Healing Microcapsule Technology in the Field of Cement-Based Materials: A Review and Prospect.

This review provides an overview of microcapsule self-healing technology and its application in the field of cement-based materials, as well as future prospects. The presence of cracks and damage in cement-based structures during service has a significant impact on their lifespan and safety performance. Microcapsule self-healing technology shows promise in achieving self-healing by encapsulating healing agents within microcapsules, which are released upon damage to the cement-based material. The review starts by explaining the fundamental principles of microcapsule self-healing technology and explores various methods for preparing and characterizing microcapsules. It also investigates the influence of incorporating microcapsules on the initial properties of cement-based materials. Additionally, the self-healing mechanisms and effectiveness of microcapsules are summarized. Finally, the review discusses the future development directions for microcapsule self-healing technology, outlining potential areas for further research and advancement.

Effects of polymeric microcapsules on self-healing composites reinforced with carbon fibers: a comparative study

Abstract Three different microcapsules, namely dicyclopentadiene (DCPD)-urea formaldehyde (UF) based single-walled microcapsules, DCPD-UF-Siloxane (DCPD-UF-Si) based double-walled microcapsules and DCPD-Carbon nanotubes-UF based dual-core microcapsules were synthesized, and their corresponding self-healing composites were prepared. This paper mainly focuses on the synthesis procedure of various microcapsules and a comparative study on the effect of microcapsules over the final composite properties. The core content of the microcapsules was measured and compared with theoretical calculations. DSC & TGA analyses have shown that the novel microcapsules (DCPD-UF-Si, DCPD-CNT-UF) and their composites have better thermal stability compared to DCPD-UF microcapsules. Epoxy-carbon fiber (2 wt.%) composite specimens with three different microcapsules were tested for surface morphology, mechanical, thermal and electrical properties. SEM analysis has shown that the microcapsules have a rough outer surface and smooth inner surface. The average diameter and shell thickness of the microcapsules were measured for all types of microcapsules. Addition of double-walled and dual-core microcapsules has reduced the glass transition temperature of the composites by 10 °C. Also, SHC with DCPD-UF-Si and DCPD-CNT-UF microcapsules have shown better thermal stability (300 °C) compared to DCPD-UF microcapsules (220 °C). The incorporation of CNT based microcapsules inside the composite has also improved the electrical conductivity by 2.2 times, without compromising on self-healing efficiency (78 %). Therefore, these novel microcapsules can be potential candidates for making multifunctional polymer composites for aerospace, windmills and automotive applications.

The effects of microcapsules with different protein matrixes on the viability of probiotics during spray drying, gastrointestinal digestion, thermal treatment, and storage

AbstractThe objective of this research was to encapsulate probiotic bacteria based on the protein matrix and investigate the influences on the survival of probiotic bacteria during spray drying, in vitro gastrointestinal digestion, heating, and storage. A probiotic isolate Bacillus coagulans BC01 was spray dried in whey protein isolate (WPI), soy protein isolate (SPI), camel whey protein isolate, or sodium caseinate. Probiotic microcapsules fabricated using WPI obtained the highest survival during spray drying, NaCl and paraxin challenges and storage, as less cell wall damage occurred during spray drying which could be observed by flow cytometer. However, the highest survivals during in vitro gastrointestinal digestion and thermal treatment were found in microcapsules with SPI matrix, which could be attributed to its relatively low solubility in water that prevented probiotics from being released prematurely, thus protecting probiotics from the damage of low pH environment and diminishing the direct contact of cells with external heat shock. In conclusion, the current study demonstrated that WPI‐based probiotic microcapsules with less cell wall damage during processing and SPI‐based probiotic microcapsules with relatively low solubility may provide better protection to adverse external environments.

Microencapsulated binary eutectic phase change materials with high energy storage capabilities for asphalt binders

Octanoic acid (OA) and tetradecane (TD) underwent mixing and the eutectic method to improve the energy storage capacities of phase change materials (PCMs) that were reduced by microencapsulation. A microencapsulated phase change material (MPCM) was synthesized by using nano-TiO2 and polyvinyl alcohol reinforced melamine formaldehyde resin as the wall and wrapping materials of OA–TD. The chemical composition, morphological structure, thermal properties, and thermal stability of the MPCM were analyzed. Additionally, the effects of microcapsules on asphalt properties and the ability to regulate asphalt temperature were investigated. The results showed that neither eutectic nor microencapsulated encapsulation produced new characteristic peaks. The MPCMs were transparent spheres with particle sizes of 1–50 μm and good formability. Compared with OA and TD, the enthalpy values of the exothermic phase transition process of OA–TD increased by 67.6% and 10.7%, respectively, and the phase transition temperature ranges increased by 53.5% and 26.7%, respectively. The exothermic enthalpy of the formed MPCM is 140.61 J/g, which provides latent heat and good thermal stability when mixed with asphalt. Temperature regulation tests demonstrated that MPCM effectively reduced the cooling rate and peak temperature of asphalt. The addition of MPCM to asphalt resulted in a decrease in penetration and ductility, but an increase in softening point. At high temperatures, MPCM enhanced the apparent viscosity, composite modulus, and rutting factor of asphalt, thereby improving its high-temperature deformation resistance.

Synthesis of microcapsules containing a formaldehyde scavenger for the sustainable control of hazardous chemical release from particleboard.

Formaldehyde scavenger microcapsules were introduced into particleboard to prepare an ecofriendly particleboard with a low pollution release in response to the problem of long-term unstable free formaldehyde release from particleboards. By analyzing key parameters of formaldehyde emission from particleboard, the effects of microcapsules on the diffusion, migration and inhibition of free formaldehyde in particleboard pore structures was discussed. The results showed that microencapsulated formaldehyde scavenger prepared by an emulsification cross-linking method with chitosan as the wall material and urea as the core material resulted in a good long-term controlled release effect on formaldehyde emission. Compared with that of the control panel, the formaldehyde emission of the particleboard with microcapsules decreased by 51.4 % and 25.8 % at 28 d and 180 d, respectively. The addition of formaldehyde scavenger microcapsules increased the particleboard macroscopic pore volume, which facilitated the conversion of adsorbed formaldehyde into free formaldehyde in the pore structure, thereby promoting its migration and diffusion in the particleboard pores. Moreover, the synergistic effect of the addition-condensation and nucleophilic cross-linking of the core and wall materials quickly captured the free formaldehyde in the panels and reduced the releasable concentration of formaldehyde in the material, thus achieving the long-term effective control of formaldehyde emission.

A Study on the Healing Performance of Mortar with Microcapsules Using Silicate-Based Inorganic Materials.

Advancements in material science have led to the development of various self-healing concrete technologies. Among these is the use of microcapsule-based self-healing materials. This study evaluated the effects of self-healing microcapsules on the quality and healing properties of mortar. A silicate-based inorganic material mixture was used as the healing material tested with ordinary Portland cement. Accordingly, the effects of microcapsules (MCs) on the rheological, mechanical, and healing properties of mortar were determined. The mixing of MCs reduced the plastic viscosity and yield stress of the cement composite material owing to the particle properties of the MCs. The reduction was in proportion to the mixing ratio. The evaluation results show that the unit water permeability decreased owing to the healing reaction immediately after crack initiation. The healing rate was more than 95% at 7 days of healing age when more than 3% of MCs was mixed. This study provides a reference for the optimal mixing rate of MCs to achieve an ideal concrete healing rate.

Hybrid polymeric therapeutic microcarriers for thermoplasmonic-triggered release of resveratrol

Diabetic retinopathy (DR) is a severe ocular complication that causes retinal damage, being one of the leading causes of blindness globally, thus the development of new strategies to prevent and treat DR as well as other degenerative diseases is highly desired. This work is focused on the design and fabrication of an ingenious model of polymeric microcapsules (MC) for controlled drug delivery in human retina cells able to carry therapeutic resveratrol (RSV) molecules in tandem with active anisotropic gold bipyramidal nanoparticles (AuBPs) as efficient photothermal agents. Specifically, MC were developed via a Layer-by-Layer deposition technique, by successively adding oppositely charged polyelectrolytes on a RSV-conjugated calcium carbonate (CaCO3) core. For the monitorization and localization of the as-formed spherical fluorescent MC inside human retina pigmented epithelial (RPE) D407 cells, fluorescein isothiocyanate, a Food and Drug Administration approved fluorophore, was attached between the polyelectrolytes layers. High-performance liquid chromatography analysis revealed a loading efficiency of over 90% of RSV on the CaCO3 core and demonstrates its release upon NIR irradiation as a consequence of the thermoplasmonic effect of MC. The cytotoxicity of the RSV-carrying MC inside human retina cells was assessed by WST-1 assay. Finally, cellular internalization and localization of the MC inside living RPE cells were monitored via Conventional Fluorescence and Re-Scanning Confocal Fluorescence Microscopy. This research seeks to take use of the novel MC and implement them as potential intraocular RSV delivery vehicles for the therapy of DR.

Performance of microcapsule-based self-healing concrete under multiaxial compression with large axial strain: Mechanical properties failure mode, and pore structure

• Triaxial behavior of microcapsule-based concrete was investigated. • The effect of microcapsules on triaxial strength declined with confinement pressure. • Microcapsules improved the plastic capacity and post-peak bulk modulus of concrete. • Concrete behavior under large axial strain was controlled by granular skeletons. To promote the application of microcapsule-based self-healing concrete in engineering structures, it is important to study the mechanical behaviour under complex stress conditions. Accordingly, this study aims to investigate the mechanical behaviour of microcapsule-based self-healing concrete under the triaxial compression state with large axial strain. The self-healing concrete was prepared by mixing different dosages of UF/Epoxy microcapsules, and the influence of confinement pressure, large axial strain, and microcapsule dosage on the mechanical behaviour of concrete was investigated through uniaxial compression, conventional triaxial compression, and mercury intrusion porosimetry (MIP) test. The results show that incorporating microcapsules reduced the cohesive strength and internal friction angle of the concrete. In contrast, the influence of microcapsule dosage on triaxial strength was rapidly weakened with increasing confinement pressure. Both the incorporation of microcapsules and the application of confinement pressure can improve the plastic deformation capacity and reduce the brittleness of the specimens. In addition, microcapsules may increase the bulk modulus of the specimens in the hardening stage. It should be noted that under the action of triaxial loading with large axial strain, the ultimate strengths of specimens with different microcapsule dosages are similar, and concrete behaviour is mainly controlled by the granular skeleton.

Effects of Adding Methods of Fluorane Microcapsules and Shellac Resin Microcapsules on the Preparation and Properties of Bifunctional Waterborne Coatings for Basswood.

In this paper, urea-formaldehyde resin microcapsules with shellac resin as core material were prepared by in-situ polymerization. Morphologies of shellac resin microcapsules were characterized by optical microscope (OM) and scanning electron microscope (SEM). Both microcapsules were spherical in shape. The encapsulation property of shellac resin was proved by Fourier transform infrared (FTIR). Shellac resin microcapsules and fluorane microcapsules were added to waterborne primer or topcoat at the same time to prepare waterborne coatings with thermochromic and self-healing dual functions. The effects of microcapsules on optical properties, mechanical properties, self-healing properties, anti-aging performance, and thermoreversible discolouration mechanism of coating films were studied. These results showed that the topcoat with 10.0% fluorane microcapsules and 5.0% shellac resin microcapsules had a better comprehensive performance. At this time, the colour of coating transformed yellow into colourless at 32 °C, and it had a good colour recovery. Shellac resin microcapsules endowed the coating with self-healing performance, and the self-healing rate was 35.9%. The research results provide a reference for the progression of multifunctional wood coatings.