Papers by Keyword: Microcapsule

Abstract: This study was performed to investigate comfort properties and antimicrobial activity of cotton and nylon knits treated with microcapsules containing sea buckthorn fruit oil reported as having antimicrobial efficacy depending on concentration of microcapsules and treatment types. Chitosan-arabic gum microcapsules containing sea buckthorn fruit oil were prepared and they were treated on cotton and nylon/PU knit respectively by an experimental design of 2 different treatment types (bath immersion method and screen printing method) Χ 5 different concentration levels of microcapsules (20, 30, 40, 50, and 60% on the weight of fabric). As comfort properties, stiffness, water-vapor permeability, and air permeability were measured objectively. Antimicrobial activity was evaluated by calculating the percentage reduction of the bacterium. As results, stiffness values of the treated knits were slightly higher than those of untreated ones, which was thought not to affect touch in wear. The values of water-vapor permeability and air permeability of both cotton and nylon after the treatment were not significantly decreased. These results means that microcapsules loaded on the knits might not worsen their wear comfort. As for antimicrobial activity, more than 90% of bacterial reduction rates against S. Aureus were shown in cotton jersey by screen printing even after repeated laundry while those was found in nylon/PU tricot by bath immersion. From these results, it was concluded that chitosan-arabic gum microcapsule containing sea buckthorn fruit oil could be utilized for textiles to provide antimicrobial activity.

Abstract: The microcapsules with inorganic/organic composites as capsule wall were prepared to optimize the performance of microcapsules. The MMT stabilized Pickering emulsion was used as template in the interfacial polymerization. TDI and EDA were polymerized at the oil-water interface to form MMT/PU composite as the capsule wall to encapsulate clove oil. Under the process condition of the dosage ratio of clove oil to TDI 5:1, the content of MMT 2%, and the reaction temperature 70 °C, the embedding rate of microcapsule could reach 92.31%. The average volume diameter of microcapsules was 49.4 μm. The microcapsules were regular and basically spherical shape, smooth surface and high elasticity. TGA showed that the thermal stability of essential oil was improved. The retention rates of clove oil in microcapsules after 40 days storage at 4 °C and 25 °C were more than 80%, indicating that clove oil microcapsules were relatively stable. The relative content of eugenol, the main component in clove oil decreased after storage, while the relative content of secondary components increased.

Abstract: Simvastatin is a cholesterol-lowering agent that inhibits the microsomal activity of 3-hydroxy-3-methylglutaril-CoA-reductase (HMG-CoA reductase), enzyme that contributes in biosynthesis cholesterol. Simvastatin has short half-life elimination about 2 hours and low solubility, this condition makes its bioavailability to be quite small. Simvastatin has adverse effect such as myopathy and rhabdomyolysis because of higher dose consumption of simvastatin. Controlled drug delivery system is needed to reduce the adverse effect. One of method that is used in drug delivery system is encapsulation using biodegradable polymer such as poly(L-lactic acid) and poly(ɛ-caprolactone). PLLA and PCL was blended with fix composition PLLA : PCL 60 : 40 (%w/w) by solvent evaporation technique using Tween 80 and Span 80 as emulsifier. Based on the optimization, the best encapsulation efficiency microcapsules were obtained at concentration of Tween 80 0.025% (v/v), Span 80 1% (v/v) with stirring speed at 900 rpm for 1 hour. The encapsulation efficiency was 83.67%. The best microcapsules were dissolved in dissolution media to get drug release profile. The percentage of drug release at pH 1.2 was 0.86% for 3 hours and in the phosphate buffer solution pH 7.4 for 12.22% for 52 hours.

Abstract: In this paper, several urea–formaldehyde/epoxy microcapsules with different particle sizes were synthesized by in-situ polymerization. The chemical structure and compressive rupture load of microcapsule were characterized. The effect of microcapsule dosage, particle size and preload pressure on compressive strength of cementitious materials was studied. The result shows: when the particle size of microcapsule is 2 mm~2.5 mm, the rupture load of microcapsule is highest, more than 3N; When the microcapsule dosage is less than 2.5%, the strength loss of the matrix is relatively small; With the increase of the particle size of the capsule, the strength of the matrix decrease greatly; When the dosage of microcapsule is 2.5%, the particle size is 1.5 mm and the preload pressure is 30%~45%f_max, the compressive strength of the self-healing specimen is 8% higher than that of the non-preloaded specimens, which shows a certain self-healing performance.

Abstract: During the last few years, synthetic self-healing materials have become a new class of emerging smart materials with the ability to repair damage and restore lost or degraded properties or performance using resources inherently available to the system. Success in the design of self-healing materials is important to material safety, product reliability and prolonged lifetime. This article covers fundamental material-independent principles and different self-healing approaches for polymeric materials. Among these approaches, some depend on specific external stimulus to achieve their goal while others regain the physical properties of the pristine material without such external intervention. Both the mechanisms and performance of different methods are discussed and evaluated, along with their advantages and disadvantages. In the end, both the potential application areas and the main challenges are also discussed in this article for a better understanding of future development trend of self-healing polymeric materials.

Abstract: Microcapsules with silicone oil as core and poly (urea-formaldehyde) as shell were prepared by direct in-situ polymerization process. The influences of formaldehyde-urea molar ratios on microcapsules morphologies were investigated by scanning electron microscope (SEM). The microcapsules were characterized by fourier transform infrared spectrometer (FT-IR), particle size analyzer, simultaneous thermal analyzer. The results showed that well dispersive microcapsules were obtained with average particle size of 2.5 μm when formaldehyde-urea molar ratio was 1.8:1.0 and that the weight ratio of silicon dioxide to microcapsule was 15.4%, which produced from pyrolysis of core material silicone oil. The prepared microcapsules were expected to a kind of high-efficiency erosion inhibitor when used in propellant.

Abstract: An advanced microencapsulation for n-octadecane has been successfully developed via UV photoinduced polymerization in this study, which was characterized by some superior qualities (e.g. rapid microencapsulation, energy-saving and environment-friendly) compared to conventional microencapsulation process. The morphology, microstructure and properties of the microencapsulated n-octadecane with poly (aliphatic polyurethane acrylate) and poly (allyl methacrylate) as shell were respectively investigated by FE-SEM, TEM and DSC. The effects of UV irradiation time, shell material types and feed ration of shell-forming monomer to n-octadecane on the morphology and structure were investigated in detail. Furthermore, the photoinduced microencapsulation mechanism was interpreted clearly as well. Besides, the phase change properties were studied as well.

Abstract: In this study, the microcapsules containing binary alkane-alcohol organic eutectic of mixed n-tetradecane and 1-dodecanol (TD-DD) phase change materials as the core and poly (methyl methacrylate)(PMMA) as the shell were prepared by emulsion polymerization reaction. The microcapsules were characterized by using DSC, SEM, FT-IR and TG. The results of DSC test showed that melting and freezing temperatures of the microcapsules are-6.136 °C and 5.203 °C, and total latent heat value are-82.522 J/g and 77.632 J/g, respectively. The SEM and FT-IR analyses indicated that PMMA shell has successfully encapsulated TD-DD. The TD-DD and the microcapsules exhibited in spherical shape. Additionally, the TG test showed that the thermal stability of TD-DD was increased after encapsulation.

Abstract: The biocompatible microcapsule of carboxymethyl cellulose/chitosan is obtained through two steps: firstly, carboxymethyl cellulose (CMC) and chitosan (CS) layer-by-layer self-assemble onto melamine formaldehyde (MF) microspheres; secondly, MF template is removed. The electrostatic interaction between CMC and CS, solution ionic strength and growth of LbL membrane are investigated by IR spectra and UV-vis spectra. The morphology and size of hollow microcapsules is observed by SEM and TEM. The results show that the hollow microcapsules are spherical shape with a little distortion and the shell average thickness of one bilayer of CMC/chitosan polyelectrolyte complex was 25 nm. The result for drug delivery and release experiments, tetracycline is as the drug model, shows that tetracycline is encapsulated with a high drug loading efficiency and could be sustained release.

Abstract: Textile industry is one of the most significant worldwide water pollution sources. With the increased demand for textile products, the textile industry and its wastewater have been increasing proportionally. Microcapsule has remarkable advantages in engineering application for pollutants removal as encapsulation agent of nanoparticles (NPs) to drastically reduce the risk associated to nanotoxicity when it is in direct contact with surroundings. This work primarily focuses on the synthesis of magnetic nanoparticles augmented microcapsule in which role of temperature and initial pH was studied in relation to Fenton reaction of Methylene Blue dye. It is observed that high removal efficiency of the dye could be achieved with high temperature whereas highly acidic and alkaline condition could enhance degradation rate. The inherent catalytic and magnetic properties exhibited by Fe⁰/iron oxides NPs-PVDF microcapsules, compared to conventional activated carbon based absorbent, make them an attractive candidate to remove cationic dye from aqueous environment.