Addition Of Microcapsules Research Articles

Minimally processed yam beam roots fortified with probiotics and phenolic compound from green coffee microencapsulated

Yam beam (Pachyrhizus erosus L.) root, commonly known as jicama, is widely consumed by health-conscious individuals due to its low caloric content. However, its nutritional value is relatively low, despite containing some. To enhance these nutritional properties, jicama can be supplemented with probiotics and antioxidant compounds. In this study, the jicama pieces were coated with an edible layer containing microencapsulated Lactobacillus acidophilus, Bifidobacterium spp. and phenolic compounds derived from green coffee, which were microencapsulated using a double spray drying technique. The probiotics and phenolic compounds were dried using double spray drying with chitosan at 120 and 140 °C. The results showed that the inlet air temperature did not have a statistically significant effect (p ≥ 0.05) on the encapsulation efficiency of probiotics, chlorogenic acid and caffeine content, or antioxidant activity expressed as IC50 value (110 - 116 µg/mL). After 6 d of storage at 4 °C, the jicama supplemented with the microcapsules containing Lactobacillus acidophilus and Bifidobacterium spp. exhibited a reduction in microbial viability by 1 and 2 log CFU/g, respectively. However, the addition of microcapsules allowed a higher concentration of phenolic compounds than the control group. Minimally processed jicama containing microcapsules with probiotics and phenolic compounds could be a functional food, and the reported procedure could be applied for industrial purposes.

Effect of Two Types of Chitosan Thermochromic Microcapsules Prepared with Syringaldehyde and Sodium Tripolyphosphate Crosslinking Agents on the Surface Coating Performance of Basswood Board

In order to investigate the effect of thermochromic microcapsules on the surface coating performance of basswood board, two types of microcapsules prepared with syringaldehyde and sodium tripolyphosphate crosslinking agents were added to a UV primer and coated on the surface of basswood board. The color-change effect of the surface coating on basswood board with microcapsules added with syringaldehyde as the crosslinking agent was better than that with microcapsules added with sodium tripolyphosphate as the crosslinking agent, and the color difference varied more significantly with temperature. The effect of the two types of microcapsules on the glossiness of the surface coating on basswood board was relatively weak. The glossiness of the surface coating on basswood board with microcapsules containing syringaldehyde as the crosslinking agent showed an overall increasing trend with the increase in microcapsules, and the change trend was relatively gentle. The glossiness of the surface coating on basswood board with microcapsules containing sodium tripolyphosphate as the crosslinking agent increased first and then decreased as the amount of microcapsules added increased. The addition of microcapsules with syringaldehyde as the crosslinking agent had no significant effect on the reflectance in the visible light band of the surface coating on basswood board. Among the two groups of samples, the hardness increase in the surface coating on basswood board with syringaldehyde as the crosslinking agent was more significant. The adhesion level of the coating on the surface of the basswood board with the two microcapsules did not change. Neither of the microcapsules had a significant effect on the impact resistance of the surface on basswood board. In the comprehensive analysis, the surface coating on basswood board with microcapsules added with syringaldehyde as the crosslinking agent at a content of 4.0% had better comprehensive performance, better surface morphology, better color-change effect, and moderate mechanical properties. The color difference was found to be 21.0 at 25 °C, the reflectivity was found to be 57.06%, the hardness was found to be 3H, the adhesion was found to be five, and the impact resistance was found to be three.

Effect of Microcapsules of Chitosan-Coated Toddalia asiatica (L.) Lam Extracts on the Surface Coating Properties of Poplar Wood

Using chitosan as the shell material and Toddalia asiatica (L.) Lam extract as the core material, microcapsules of chitosan-coated Toddalia asiatica (L.) Lam extracts were prepared. The microcapsules were added to waterborne topcoats to investigate the effects of different content and MToddalia asiatica(L.) Lam extracts:Mchitosan (MT:MC) on the performance of waterborne coatings on poplar surfaces. Under different MT:MC of microcapsules, the content of microcapsules in the coating was negatively correlated with the glossiness, reflectivity, and adhesion of the coating. The addition of microcapsules reduced the liquid resistance of the coating to citric acid and improved the ethanol and cleaning agent resistance of the coating. The hardness, impact resistance, and roughness of the coatings increased gradually with the increase in microcapsule content. The content of microcapsules was positively correlated with the Escherichia coli and Staphylococcus aureus antibacterial performance of coatings, and the coatings had a slightly higher antibacterial rate against Staphylococcus aureus than Escherichia coli overall. The poplar surface coating with 5.0% microcapsules and MT:MC of 4.0:1 was excellent: the gloss was 5.30 GU, the light loss rate was 62.22%, the color difference ΔE was 22.93, the hardness was HB, the impact resistance was grade 3, the adhesion was grade 2, the roughness was 2.022 µm, the resistance to ethanol and cleaning agent was grade 2, and the resistances to Escherichia coli and Staphylococcus aureus were 74.21% and 82.01%, respectively. The results of the study provide a technical reference for the application of antibacterial waterborne coatings on wood surfaces.

Encapsulation of β-carotene in gelatin-gum Arabic-sodium carboxymethylcellulose complex coacervates: Enhancing surimi gel properties and exploring 3D printing potential

This study investigates the utilization of functional additives (β-carotene microcapsules) and 3D printing technology for the production of innovative surimi products. The β-carotene microcapsules were prepared using different ratios of gelatin (Ge), gum Arabic (Ara), and carboxymethylcellulose sodium (CMC). Among these ratios, the ratio of 5:5:1 (Ge:Ara:CMC) resulted in more stable microcapsules spherical structures and better environmental stability. Subsequently, different concentrations (5–20 %) of the obtained β-carotene microcapsules were added to surimi samples. As the concentration increased, there was an improvement in the gel strength of the surimi. However, no significant changes were observed when the concentration was 15 % (p > 0.05). All samples exhibited shear thinning behavior. The addition of microcapsules improved the resilience and thixotropy of surimi, making it more suitable for 3D printing applications. The inclusion of β-carotene microcapsules in surimi products not only meets the nutritional needs of consumers, but also provides valuable insights for the development of functional surimi products.

MXene decorated hierarchical phase change microcapsules to strengthen the tribological properties of PPS/PTFE fabric composites

The reduction of the wear rate and friction coefficient of composites simultaneously has a great challenge. Herein, a unique phase change microcapsule is designed with n-docosane as the core, TiO2 coated with sodium alginate as the shell, as well as surface-decorated Ti3C2Tx nanosheets. In this microcapsule system, n-docosane absorbs part of the frictional heat via solid-liquid phase change and releases it continuously to achieve self-lubrication. The TiO2 shell possesses excellent load-bearing capacity and Ti3C2Tx is susceptible to interlayer slip, which reduces the friction and wear of fabric composites. The results indicate that an average wear rate and friction coefficient of fabric composites are decreased by 60.85 % and 11.83 % with the addition of microcapsules. A strong and continuous tribofilm is formed on the steel surface, and the tribofilm enhances the boundary lubrication of the steel counterpart. This paper is expected to provide a novel design thought for the application of core-shell structure in tribology.

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.

Microencapsulation of peanut skin polyphenols for shelf life improvement of sunflower seeds.

Derived from industrial processing waste, peanut skins contain polyphenols that delay oxidative food spoilage. However, these compounds are susceptible to light, heat, and oxygen exposure. Microencapsulation provides a solution by offering protection from these factors. The aim of this study was to evaluate the protective effect of peanut skin extract microcapsules on the chemical, microbiological, and sensory property and shelf life of sunflower seeds during storage. Five roasted sunflower seed samples were prepared: control (S-C); added with butylhydroxytoluene (S-BHT); coated with carboxymethyl cellulose (S-CMC); coated with CMC and the addition of peanut skin crude extract (S-CMC-CE); coated with CMC and the addition of microcapsules (S-CMC-M20). Sensory acceptability was determined using hedonic testing. Chemical (peroxide value, conjugated dienes, hexanal and nonanal content, and fatty acid profile), microbiological, and descriptive analyses were carried out on samples stored for 45 days at room temperature. Shelf life was calculated using a simple linear regression. All samples were microbiologically fit for human consumption and accepted by consumer panelists, scoring above five points on the nine-point hedonic scale. S-CMC-M20 exhibited the lowest peroxide value (6.59meqO2/kg) and hexanal content (0.4µg/g) at the end of the storage. Estimated shelf life showed that S-MC-M20 (76.3 days) extended its duration nearly ninefold compared to S-C (8.3 days) and doubled that of S-CMC-CE (37.5 days). This indicates a superior efficacy of microencapsulated extract compared to its unencapsulated form, presenting a promising natural strategy for improving the shelf life of analogous food items. PRACTICAL APPLICATION: Incorporating peanut skin extract microcapsules in coating sunflower seeds presents a promising strategy to extend the shelf life of lipid-rich foods, capitalizing on the antioxidant properties of polyphenols. This innovative approach not only enhances nutritional quality but also addresses sustainability concerns by repurposing agro-industrial byproducts, such as peanut skins. By meeting consumer demand for functional foods with added health benefits, this technique offers potential opportunities for the development of novel, value-added food products while contributing to circular economy principles and waste management efforts.

The Effect of Self-Healing Microcapsules in Corrosion Testing on Magnesium AZ31 Alloy and Fibre Metal Laminates

Fibre metal laminates (FMLs) are the most interesting composite materials of the past decade. They possess the properties of both polymer composites and metallic alloys. However, there is a problem with corrosion when the outer layers are made of aluminium or magnesium. The electrochemical changes that occur during the corrosion process and the mechanisms associated with the corrosion phenomenon are still being investigated. Recently, self-healing phenomena have emerged as a useful approach to prevent corrosion. However, there is limited research on the combination of FMLs and self-healing layers. Therefore, the main purpose of this article is to evaluate the self-healing ability of a magnesium/PEO layer based on microcapsules in a corrosion environment. It was observed that the corrosion mechanism in magnesium alloys is very complex. However, the use of a barrier layer with PEO treatment and microcapsules yielded positive anti-corrosion results. The FML samples were subjected to a 6-week corrosion test, and the addition of microcapsules to the layers showed positive results. In contrast, the samples without microcapsules exhibited intergranular corrosion. In the future, comprehensive tests using self-healing microcapsules in FMLs could greatly enhance their anti-corrosion properties and improve the integrity of the structure.

Dynamic splitting behavior of microcapsule-based self-healing cementitious composites under SHPB impact loading

This study presents an experimental study on the dynamic splitting tensile performance of microcapsule-based self-healing cementitious composites and fiber-reinforced microcapsule cementitious composites. The research aims to determine the effect of microcapsule dosages, fiber types, and strain rates on the dynamic splitting tensile behavior of materials. A total of 99 specimens were subjected to the split Hopkinson pressure bar (SHPB) impact loading within the strain rates of 0.85–17.12 s−1. A high-speed camera was employed to capture the crack propagation process, and scanning electron microscopy (SEM) was used to characterize the corresponding microstructure. The results indicated that the splitting tensile performance of materials exhibits significant strain rate sensitivity. The addition of microcapsules increases the dynamic splitting tensile strength of the material, and the highest energy absorption capacity can be achieved with a 5 % microcapsule dosage. The incorporation of polyvinyl alcohol (PVA) and polyethylene (PE) fibers effectively enhances dynamic splitting tensile strength and energy absorption capacity, achieving optimal performance with the incorporation of PVA-PE hybrid fibers. Furthermore, the investigation of the dynamic increase factor (DIF) of the material indicates that fibers heighten the strain rate sensitivity of the material.

Fabrication of microcapsules with graphene/organic hybrid shell based on Pickering emulsions for self‐healing anti‐corrosive coatings

AbstractDuring the utilization of organic coatings, microcracks may arise as a result of external environmental influences and inherent aging, significantly diminishing the coating's lifespan. In this study, we employed the Pickering emulsion template method combined with interfacial polymerization to fabricate graphene oxide/polyurethane/polyaniline (GO/PU/PANI) organic–inorganic hybrid shell microcapsules utilizing isophorone diisocyanate (IPDI) as the core material. The capsules exhibited an average particle diameter of 3.11 μm and an encapsulation rate of 78.19%. Subsequently, these prepared capsules were incorporated into a photocurable resin to obtain a self‐healing corrosion‐resistant coating. Scanning electron microscopy analysis demonstrated that even with just 5% addition of microcapsules, nearly complete repair could be achieved. The tensile strength and flexural strength of the self‐healing material containing 5% microcapsules were measured at 84.8 MPa and 193 MPa respectively. These values represented only a marginal decrease in tensile strength by 2.75% and flexural strength by 5.39%, compared to the substrate without capsule addition. Remarkably, after immersing the repaired coating in a NaCl solution with a concentration of 5 wt% for up to 250 hours, the alternating current impedance value remained stable at approximately 6.9 × 105 Ω·cm2. This outstanding corrosion resistance can be attributed to synergistic effects between PANI and IPDI within the coating system, thereby expanding its potential applications under harsh conditions.

Investigation of rheological properties of asphalt modified with low-temperature microencapsulated eutectic phase change materials

The effects of microencapsulated eutectic phase change materials (MEPCMs) on the viscosity-temperature relationship, viscoelasticity, creep recovery, and low-temperature properties of base asphalt and SBS asphalt were investigated using dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The results revealed that the incorporation of microcapsules led to a reduction in the complex modulus and viscosity of the asphalt. Notably, at a concentration of 13 wt%, microcapsules disrupted the linear viscoelastic behavior of the asphalt and compromised its phase uniformity. However, the addition of microcapsules improved the low-temperature rheological properties of the asphalt. Specifically, the S and m-values of the asphalt decreased and increased, respectively, with increasing microcapsule content. Moreover, SBS asphalt exhibited less susceptibility to the effects of microcapsules compared to base asphalt, owing to its superior performance across a wide range of temperatures. This characteristic renders SBS asphalt more compatible with MPCMs for practical applications.

A Functional Bread Fermented with Saccharomyces cerevisiae UFMG A-905 Prevents Allergic Asthma in Mice

BackgroundThe administration of probiotics has been shown to be beneficial in asthma. The administration of Saccharomyces cerevisiae UFMG A-905 prevented asthma development. Traditionally, probiotics are administered using dairy-based matrices, but other vehicles (e.g., fruit juices, biscuits, candies, and breads) can be used. ObjectivesThis study aimed to assess the effect of bread fermented with S. cerevisiae UFMG A-905 in asthma prevention. MethodsThree breads were produced: fermented with commercial yeast, fermented with S. cerevisiae UFMG A-905, and fermented with S. cerevisiae UFMG A-905 with the addition of alginate microcapsules containing live S. cerevisiae UFMG A-905. Characterization of the microbial composition of the breads was performed. Male Balb/c mice were sensitized and challenged with ovalbumin. Breads were administered 10 d before the first sensitization and during sensitization and challenge protocol. Yeast fecal count, in vivo airway hyperresponsiveness, and airway and lung inflammation were assessed. ResultsIn UFMG A-905 bread, there was an increase in yeast number and a decrease in total and lactic acid bacteria. Animals that received S. cerevisiae UFMG A-905 fermented bread with microcapsules had a significant increase in yeast recovery from feces. S. cerevisiae UFMG A-905–fermented breads partially reduced airway inflammation, decreasing eosinophils and IL5 and IL13 concentrations. When adding microcapsules, the bread also diminished airway hyperresponsiveness and increased IL17A concentrations. ConclusionsS. cerevisiae UFMG A-905 was able to generate long-fermentation breads. Microcapsules were a safe and viable way to inoculate the live yeast into food. The administration of breads fermented with S. cerevisiae UFMG A-905 prevented asthma-like characteristics, being more pronounced when the breads contained microcapsules with live yeast.

Self-healing properties of microencapsulated linseed oil-poly(urea formaldehyde) additives embedded polyester coating on Galvalume steel sheet

ABSTRACT Linseed oil and poly(urea-formaldehyde)-based microcapsules with an 82% weight ratio of core/shell and a mean outer diameter of about 100 μm were synthesised by in-situ polymerisation. These microcapsules were dispersed in polyester paint and then primer-coated Galvalume sheets were painted with microcapsule loaded (MC) and neat (no microcapsules) paints. These painted samples were scribed and examined using various characterisation techniques to evaluate their self-healing properties. SST and CCT showed that the electrolyte diffusion was suppressed in the MC sample, whereas the neat sample was noticeably blistered due to under-film corrosion. Scanning Kelvin Probe microscopy, SKP supported this finding wherein the Volta potential of the neat sample increased in the positive direction indicating cathodic delamination, whereas no significant change occurred in the MC sample. SEM-EDAX revealed the surface morphology and composition of the samples. Furthermore, EIS showed that microcapsule addition increased the pore resistance and decreased the coating capacitance of the polyester paint.

Tribological performances of polytetrafluoroethylene/Kevlar fabric liner reinforced by oil-containing microcapsules

The wear depth of polytetrafluoroethylene (PTFE)/Kevlar fabric liner is directly related to the service life of self-lubricating spherical plain bearings. Herein, two kinds of oil-containing microcapsules were applied to improve the wear properties of PTFE/Kevlar fabric liner at various temperatures. The addition of microcapsules successfully reduced the wear and COF simultaneously, which was owing to the synergistic effect of hard shell and liquid lubricants core. The hard shell enhanced the mechanical strength of PTFE, while the released lubricants made up the shortcoming due to the incomplete PTFE lubricating film, and inhibited the abrasive wear of SiO2 debris. The present work suggested that the addition of oil-containing microcapsules was an effective method to enhance the tribological performances of PTFE/Kevlar fabric liner.

Preparation and characterization of phase change microcapsules for improving the applicable temperature and stability of high temperature resistant drilling fluids

High temperature environment has many negative effects on the drilling fluid system. In order to avoid or delay these negative effects, phase change materials (PLMs) microcapsule technology was introduced into the high temperature drilling fluid system in this study to further improve the applicability of the high temperature resistant drilling fluid under extremely high temperature formation environment. The microcapsules circulate with drilling fluid, and PLMs melt endothermically at high temperature in deep formation and solidify exothermically at shallow formation. A PLMs microcapsule with solar salt (NaNO3: KNO3 = 3:2) as core material and nano silica as shell material was prepared by sol-gel interfacial polymerization. The structure and properties of the microcapsules were characterized, the temperature-control performance of the microcapsule and its stability and compatibility with drilling fluid were evaluated. The results showed that the microcapsules were well encapsulated, and the single microcapsule particles were spherical, but there was a certain agglomeration phenomenon. The particle size distribution of microcapsules was concentrated in 4–16 µm, with a median particle size of 7.79 µm. The highest encapsulation rate was 60.6%, and the melting enthalpy was 68.48 J/g. The microcapsules had no obvious mass loss below 400 ℃ and had excellent thermal stability. It was proved that the microcapsules had good sealability, shear stability and cycling stability, with the enthalpy/mass retention rate all above 90%. The addition of microcapsules will not affect the basic properties of drilling fluid, and can reduce the peak temperature of high temperature drilling fluid. Different from existing researches, this paper uses a method that absorbs heat to slow down the heating rate of drilling fluid in the formation. This is a new idea, which is expected to be widely studied in the field of high temperature drilling fluids.

Effectiveness of Rhizospheric Bacteria Microcapsules Addition on The Growth of Cocoa Leaves (Theobroma cacao L.)

Cocoa (Theobroma cacao L.) is one of the main plantation commodities which plays an important role in the Indonesian economy, and 3rd ranked in the world for cocoa producers. One effort to increase cocoa productivity was the use of biological fertilizer. The aim of this research was to determine the effect of using rhizosphere bacterial microcapsules as biofertilizer on the vegetative growth of cocoa leaves. The research design used was a Completely Randomized Design, with two factors, the first was immersion the cocoa beans using a rhizosphere bacterial suspension consisting of A0=0 hours; A1= 8 hours; A2=16 hours and A3=32 hours and the second factor is the addition of microcapsules consisting of C0=0 gram( g ); C1=10gr, C2=20gr, C3=30gr. Combination The treatment was repeated twice so that 32 plants were obtained. For the parameter of observing the number of leaves, the best results were shown in the 8 hour immersion treatment with an average number of leaves of 12.63, followed by the treatment of giving 20 grams of capsules with an average number of leaves of 11.75. The lowest number of leaves was shown in the 16-hour and 32-hour immersion treatments at 10.75. Meanwhile, for the observation parameters of leaf area, the best results were shown in the 32 hour immersion treatment with an average leaf area of 73.49 cm 2 and the lowest results were shown in the non-immersion treatment with an average leaf area of 59.88 cm 2 . The results of the analysis of variance showed that all treatments had no significant effect

Effect of Composite Addition of Antibacterial/Photochromic/Self-Repairing Microcapsules on the Performance of Coatings for Medium-Density Fiberboard

In order to expand the research on a combination of functional microcapsules and water-based coatings, antibacterial microcapsules using 3.0% sodium dodecyl benzene sulfonate as an emulsifier, self-repairing microcapsules, and photochromic microcapsules were added to water-based coatings separately or in combination and coated on medium-density fiberboard to analyze the various properties of the coating. From the perspective of the antibacterial effect, the photochromic microcapsules have little negative impact on antibacterial properties and can be used in combination with antibacterial microcapsules. When the photochromic microcapsules and antibacterial microcapsules were combined, their antibacterial rates against Staphylococcus aureus and Escherichia coli were 51.9% and 55.6%, respectively. The self-repairing microcapsules in combination with antibacterial microcapsules lead to a significant decrease in the antibacterial rate and are not suitable for use in combination with antibacterial microcapsules. From the perspective of the photochromic effect, the addition of self-repairing microcapsules can accelerate the photochromic speed of the coating, improving the photochromic effect. The addition of antibacterial microcapsules made the photochromic rate slower. Both the antibacterial microcapsules and photochromic microcapsules have weakened the self-repairing ability of self-repairing microcapsules. The width change rate in coating scratches has decreased from 21.9% to 14.7% and 17.6%, respectively. However, compared with the coating without microcapsules, the self-repairing ability still improved. The results have broad prospects in the application of antibacterial microcapsules, self-repairing microcapsules, and photochromic microcapsules for coatings on medium-density fiberboards.

Microencapsulated epoxidized palm oil: A self-healing coating solution

Coatings are susceptible to cracking due to chemical exposure and mechanical forces. To enhance their durability and self-healing properties, microcapsules are utilized. In this study, poly(urea formaldehyde) microcapsules containing epoxidized palm oil as the core material were synthesized and investigated for their self-healing properties in diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The epoxidation reaction of palm oil was carried out by varying reaction times and the molar ratio of hydrogen peroxide to formic acid to achieve an effective oxygen carrier with a high oxirane oxygen content. The formation of epoxide groups was confirmed using Fourier transform infrared spectroscopy (FT-IR) and Fourier transform Nuclear Magnetic Resonance Spectroscopy (NMR). The core-shell structure of the microcapsules was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Pencil hardness and adhesion tests were conducted on the epoxy coatings containing different amounts of microcapsules to evaluate the impact of microcapsules on hardness and adhesion properties. The epoxy coatings with microcapsules demonstrated significant self-healing ability and provided effective anti-corrosive protection. Higher microcapsule contents resulted in improved self-healing performance. Furthermore, the addition of microcapsules at 5 to 15 wt % did not compromise the hardness and adhesion properties of the epoxy coating.

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.

Intelligent de-icing epoxy coating surface using bionics secreting oil microcapsules

Ice on the surface of outdoor equipment or aircraft under low temperatures often brings serious consequences. Functional coating materials with intelligent de-icing performance have become one of the research hotspots in materials science. Inspired by the bionic de-icing structure of penguin feather secretion oil, the aim of this work was to design and prepare an environmental-friendly intelligent de-icing epoxy coating surface with bionic microcapsule. The core material of the microcapsules is the hydrophobic oily liquid of glyceryl tri(2-ethylhexanoate) (C27H50O6), which can be secreted from and the hexamethoxymethyl melamine resin (HMMM)/polyvinyl alcohol (PVA) shells. Morphology analysis confirmed that the microcapsules were successfully fabricated with core-shell structure and global shape. The microcapsules dispersed homogeneously in epoxy coating with an appropriate ratio of around 3.0–4.0 wt%. No interface debonding appeared between epoxy and microcapsules. Microcapsules had excellent thermal stability and resisted violent repetitive temperature changes without rupture. Chemical analysis of the shell confirmed the existence of gel PVA in pores of the cross-linked HMMM framework structure. Because the core materials penetrated shells through pores, it caused the increase in surface hydrophobicity of coatings. The release capability of the core material was enhanced by increasing the PVA content in shells and higher content of microcapsules in coatings. However, the excessive addition of microcapsules reduced the wear resistance of the epoxy coating. According to the ice shearing force test results, only 1.0 wt% addition of PVA/HMMM microcapsules significantly improved the de-icing performance of epoxy coating even under temperatures of − 20 °C. The reason was that the released oily molecules could dramatically reduce the adhesion between ice and epoxy.