Papers by Keyword: Microcapsule

Abstract: In this study, it was aimed at preparing and characterizating of poly (methyl methacrylate) (PMMA) shell microcapsules containing tetradecanol as phase change materials (PCMs) for thermal energy storage. The tetradecanol microcapsules were characterized by using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The test result show that the contents of tetradecanol in microcapsules nearly 57.5% and the latent heats of melting and freezing were found to be 120.7 and 118.4 J/g. TGA analyses also indicated that the microPCMs degraded in two steps and have good thermal stability.

Abstract: A series of microcapsules were prepared by interfacial polymerization method using epoxy and urea formaldehyde resin as core material and shell material, individually. The effects of processing conditions on the properties of epoxy microcapsules were systematically investigated based on w(Core), average diameter and decomposition temperature of microcapsules through the method of orthographic factorial design and the most optimum processing conditions were included. The results indicated that core/shell mass ratio was the most important factor on w(Core), average diameter and decomposition temperature of microcapsules. The optimum processing conditions were concluded: 1:1 for the core/shell mass ratio, 300 rpm for agitation rate and 0.8% DBS as emulsifier. The microcapsules prepare in the optimum processing conditions were well encapsuled and presented thin shell and smooth surface. Moreover, the addition of 10% microcapsules can improve the mechanical properties of epoxy matrix greatly.

Abstract: s: For the problem that cracks exist when the advanced materials are attacked or shocked, and the cracks are hard to self-healing. The microcapsules are put forward to make great effects on healing the cracks to some extents. The manufacturing methods of microcapsules are reviewed, including Matrix Polymerization, In-situ Polymerization, In-situ Cross-linking, Solvent Evaporation Method. And the conclusion and problems are prospected finally.

Abstract: In this paper, paraffin/polyurea (PU) phase change microencapsules were prepared through an interfacial polymerization method using composite paraffin with solid/liquid mass ratio 3:7 as core materials, 2,4 toluene diisocyanate (TDI) and ethylenediamine (EDA) as monomers, NP-10 as an emulsifier. It was explored the effect of the monomer mass ratio m_EDA: m_TDI on the yield of hollow PU microcapsules, and the effect of core/shell ratio on the particle size and coating efficiency and storage-energy performance of paraffin/PU phase change microencapsules. The experimental results showed the PU yield is increasing with the increasing of EDA:TDI mass ratio until 0.5:1,then keeps the constant. Paraffin/PU phase change microencapsules prepared with the core-shell ratio of 2:1 have better performance: the melting point of 28.1°C, the enthalpy of 58.4KJ/Kg, encapsulation efficiency of 87.5%, the average particle size of 4.32μm, and the uniform particle size distribution.

Abstract: Anthocyanins microcapsules from Acanthopanax.sessiliflorus (Rupr. et Maxim.) Seem were prepared by Spray-Drying, using maltodextrin and gum arabic as wall materials. The stability and releasing property of anthocyanins microcapsules were studied. Using the retention rate as evaluation index, the effects of temperature, light, pH and metal ions on the stability of microcapsules and anthocyanins during 30 days storage were assessed, and samples were taken every five days. Results show that the microcapsules have greater storage stability against temperature, light, pH and metal ions. Using the release rate as evaluation index, the effect of releasing of microcapsules was evaluated, and samples were taken every 30min. Results show that the microcapsules have certain slow-release effect.

Abstract: Alginate-chitosan multilayer beads containing α-glucosidase inhibiting peptide (GIP) from Ruditapes philippinarum were prepared to develop stable, non-toxic microcapsules. The optimal conditions were alginate concentration (w/v) 1.0%, alginate/GIP ratio (w/w) 1:5, calcium chloride concentration (w/v) 5% and chitosan concentration (w/v) 2.0%, which were obtained through single factor tests and orthogonal experiments. Under the conditions, the encapsulation efficiency (EE%) was 67.21% and the drug-loading percentage was 33.67%.According to the release study, the release rate of GIP was lower than 30% after incubation in simulated gastric fluid (SGF) for 3h and the rate was higher than 70% after incubation in simulated intestinal fluid (SIF) for 5h. The inhibiting rate was 25.13% after treatment in SIF when the concentration of GIP was 10mg/mL. Accordingly,the microcapsules prepared in this paper are acid resistant and therefore can be given orally.

Abstract: Carboxylic waterborne polyurethane was synthesized with isophorone diisocyanate (IPDI), polyether glycol (PPG) and 2,2-bis (hydroxymethyl) propionic acid (DMPA) as major materials, and terminated with C=C by using β-hydroxyethyl ethacrylate (HEMA). And then 2, 2-azobis (isobutyronitrile) (AIBN) and cumene hydroperoxide (CHPO)/tetraethylenepentamine (TEPA), as a representative of different kinds of initiators, were employed to prepare SiO₂/polymer composites via double in situ miniemulsion polymerization, in which the prepared waterborne polyurethane was used as a reactive surfactant. The morphology of SiO₂/polymer, the microstructure and thermal properties were characterized and discussed. The results indicated that the morphologies of SiO₂/polymer composites initiated by AIBN with waterborne polyurethane as surfactant, which showed core-shell microcapsulated structure with SiO₂ microsphere fabricated inside the shells of polymer, were different from the products prepared by conventional surfactant. Morphological evolution of the particles with polymerization and their dependence on types of initiator played key roles in achieving the microencapsulated shapes.

Abstract: In this paper, Microencapsulated paraffin/polyurea (PU) phase change materials were prepared through an interfacial polymerization method using composite paraffin with solid/liquid mass ratio 3:7 as core materials, 2,4 toluene diisocyanate and ethylenediamine as monomers, NP-10 as an emulsifier. It was investigated the effects of emulsion speed, the amount of emulsifier and polymerization temperature on the particle size and coating efficiency and storage-energy performance of microencapsulated paraffin / PU phase change materials. The results showed when the emulsion speed is 2000r/min and the amount of emulsifier to core material is 6% and the polymerization temperature is 70°C, Microencapsulated paraffin / PU phase change materials have better performance: the melting point of 28.1°C, the enthalpy of 58.4KJ/Kg, coating efficiency of 87.5%, the average particle size of 3~4μm, and the uniform particle size distribution.

Abstract: With the adoption of surface modification method, microencapsulated phase change materials (MEPCM) with polyurea as wall materials, paraffin as core materials were successfully prepared. This paper made a research on the effect dosage of modifier might have on the content of microcapsule core materials. Findings indicated that the content of microcapsule core materials was relatively high as the dosage of modifier being core material 10 wt%. It was preliminarily proved that polyurea had been coated on the surface of paraffin particles by adopting Fourier Transform Infrared Spectrum (FTIR) to formulate the composition and structure of microcapsules. And the laser particle analysis declared that particle size distribution of microcapsules was narrow with average particle size of 389 μm. Thermo Gravimetric Analysis (TG) and Differential Scanning Calorimetry (DSC) were also employed to make a representation of the thermal properties of microcapsules, and it was shown that microcapsules were of wonderful phase change performance and thermal stability.

Abstract: In order to study the fabrication of T-shape combined micronozzle used for preparation of microcapsules, a gravity based apparatus for glass micronozzle was designed. A novel method for glass micro hole was proposed. The impact law of pull force, coil temperature, delay time, coil width on pull process, heating time, feed distance on forge process, and heating area on micro hole fabrication process were experimentally researched. Sealed by UV optical glue, a kind of T-shape combined glass micronozzle was prepared. Orderly core oil emulsion in sodium alginate solution and core oil, poly microsphere (PS) and glass microsphere microcapsules were prepared based on combined pulse dispensing with the T-shape micro-nozzle. Results showed that the T-shape combined glass micronozzle had the advantage of simple structure, low cost, good bio-chemical and optical character and the T-shape micronozzle could be used to produce multiphase liquid flowing and dispensing. It is promising to be applied wildly in other areas.