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Solvent Type (solvent + type)
Selected AbstractsEffect of Plasticizer Concentration and Solvent Types on Shelf-life of Eggs Coated with ChitosanJOURNAL OF FOOD SCIENCE, Issue 4 2006Su Hyun Kim ABSTRACT:, Effects of plasticizer concentrations (0, 0.5, 1.0, 1.5, and 2.0% glycerol) and solvent types (1% acetic and 1% lactic acid) on internal quality of eggs coated with 2% chitosan solution were evaluated during 5 wk of storage at 25 °C. In comparison of plasticizer concentrations, eggs coated with chitosan dissolved in acetic acid containing 2% glycerol showed significant reduction in weight loss compared with the noncoated eggs during 5 wk of storage. At 2% glycerol, the Haugh unit and yolk index values suggested that chitosan-coated eggs can be preserved for at least 3 wk longer than the control noncoated eggs during 5 wk of storage at 25 °C. Use of acetic acid rather than lactic acid as a chitosan solvent was more advantageous in view of shelf-life extension of eggs. [source] Synthesis of CdSe quantum dots with luminescence in the violet region of the solar spectrumLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 1 2010Nisha Shukla Abstract We have designed a simple, one-step synthesis of CdSe quantum dots with photoluminescence frequencies ranging from the red through to the violet region of the solar spectrum. The photoluminescence peaks have FWHM of 30 nm indicating absorption over a narrow range of wavelengths. The effect of solvent type and solvent boiling point on the physical and photoluminescence properties of the quantum dots has been studied. High boiling point, non-polar solvents shift the photoluminescence peak to longer wavelengths and low boiling point, polar solvents shift the photoluminescence peak to shorter wavelengths. Copyright © 2009 John Wiley & Sons, Ltd. [source] Biodegradable Polymeric Microcarriers with Controllable Porous Structure for Tissue EngineeringMACROMOLECULAR BIOSCIENCE, Issue 12 2009Xudong Shi Abstract Porous microspheres fabricated by biodegradable polymers show great potential as microcarriers for cell cultivation in tissue engineering. Herein biodegradable poly(DL -lactide) (PLA) was used to fabricate porous microspheres through a modified double emulsion solvent evaporation method. The influence of fabrication parameters, such as the stirring speed of the primary and secondary emulsion, the polymer concentration of the oil phase, and solvent type, as well as the post-hydrolysis treatment of the porous structure of the PLA microspheres are discussed. Good attachment and an active spread of MG-63 cells on the microspheres is observed, which indicates that the PLA microspheres with controllable porous structure are of great potential as cell delivery carriers for tissue engineering. [source] Morphological and Physical Properties of Triblock Copolymers of Methyl Methacrylate and 2-Ethylhexyl MethacrylateMACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2006Hormoz Eslami Abstract Summary: Triblock copolymers of methyl methacrylate (MMA) and 2-ethylhexyl methacrylate (EHMA) [that is, poly(MMA,EHMA,MMA)] were prepared by an emulsion atom-transfer radical polymerization. The relationships of their structural, morphological, and physical properties were investigated. The latex particles had core-shell morphologies and the block copolymers experienced phase separation. Small latex particles with a low number of cores could deform and wet silicon-wafer surfaces, but the deformation of large latex particles was restricted by the internal two-phase morphology of the particles. Latex casting produced continuous pinhole-free films, in which hard poly(MMA) (PMMA) cores of different latex particles merged and provided interparticle connections. The morphology of solution-cast films depended on block composition, solvent type, and film thickness. For all the prepared polymer samples, thick films cast in toluene had poly(EHMA) (PEHMA) materials at air surface, whereas those cast in tetrahydrofuran had a sponge-like PMMA surface structure. Thin toluene-cast films from P(MMA,EHMA,MMA) with the block degrees of polymerization () 200,930,200 showed spherical PMMA domains and those from 380,930,380 yielded a protruded worm-like PMMA structure. The copolymer materials were coated on a glass surface for peeling tests. The films gave good hot-melt adhesion properties when the of the PEHMA block was over 600. The peeling strength depended on the lengths of both PEHMA and PMMA blocks. The P(MMA,EHMA,MMA) sample with of 310,930,310 yielded the highest peeling strength of 7.4 kgf,·,inch,1. The developed material is demonstrated to be a good candidate for a solvent-free, hot-melt, pressure-sensitive adhesives for special-purpose applications such as medical tapes and labels. [source] Synthesis of Composite Polystyrene/Silica Nanoparticles via Precipitation and Emulsion Polymerization MethodsMACROMOLECULAR REACTION ENGINEERING, Issue 5 2010Katerina Kotti Abstract Polystyrene/silica composite nanoparticles were synthesized via precipitation and emulsion polymerization methods, in the presence of a basic co-monomer (e.g., 4-VP and 1-VID), and a colloidal aqueous silica solution. The effects of key process parameters, that is, solvent type, monomer/co-monomer volume ratio and total monomers concentration for precipitation polymerization, and reaction temperature, pH value, initial silica-sol concentration and initial monomer/co-monomer molar ratio for emulsifier-free emulsion polymerization on the particle morphology, silica content, and particle size distribution of the composite nanoparticles were experimentally investigated. Stable, spherical, and uniform in size composite nanoparticles were synthesized by both techniques. The average particle diameter varied from 108 to 182,nm for the emulsifier-free emulsion polymerization and from 400 to 800,nm for the precipitation polymerization, while the silica content was as high as 38.3,wt.-% for the former method and up to 15.5,wt.-% for the later. The synthesized composite polymer/silica particles were then electrolytically co-deposited with zinc on steel plates to improve the corrosion resistance of the metal's surface. [source] Effect of ,-irradiation on the physical properties and dyeability of poly(vinyl butyral) blends with polystyrene and poly(ethylene glycol)POLYMER COMPOSITES, Issue 6 2008Horia M. Nizam El-Din Cast films of polymer blends essentially based on poly(vinyl butyral) (PVB) and equal ratios of polystyrene (PS) and poly(ethylene glycol) (PEG) were prepared from benzene and butyl alcohol solutions of the individual polymers. The effect of ,-irradiation on the thermal decomposition and tensile mechanical properties was investigated. Moreover, the effect of ,-irradiation on the dye affinity of PVB/PS and PVB/PEG for basic and acid dyestuffs was studied. The thermogravimetric analysis (TGA) study showed that the unirradiated PVB polymer films prepared in benzene displayed higher thermal stability than the same polymer films prepared in butanol. However, in all cases the thermal stability was found to increase with increasing ,-irradiation dose. On the other hand, PVB/PS blend possesses higher thermal stability than PVB/PEG, as shown from the determination of the weight loss (%) at different heating temperatures, the temperatures of the maximum rate of reaction and the activation energy. While, pure PS films showed the stress-strain behavior of brittle polymers, PVB/PS films showed the behavior of tough polymers with yielding properties. The results of dyeing clearly showed that the solvent type, blend composition, and irradiation dose are determining factors for the dye affinity for basic or acid dyes. For example, unirradiated PVB films prepared from butanol displayed a higher affinity for the basic and acid dyes than the same polymer prepared from the same benzene. However, PVB prepared from butanol showed higher affinity to the dyes than PS prepared from the same solvent. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Study of the mechanism of microwave-assisted extraction of Mahonia bealei (Fort.) leaves and Chrysanthemum morifolium (Ramat.) petalsFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2004Shan Gao Abstract A study of microwave-assisted extraction (MAE) for berberine in Mahonia bealei (Fort.) was carried out with batch equipment, in order to investigate the mechanism of the extraction related to structural changes in the glands. The extracts were analysed by ultraviolet-visible spectrophotometry at 347 nm. The parameters investigated were solvent types, the intensity of microwave energy and the process ratio (g/ml) of materials to solvent volume. The microwave-assisted extraction of different moisture content of materials was developed and optimized by means of three-factor and three-level orthogonal designs. Electron and optical micrographs of M. bealei (Fort.) leaves and Chrysanthemum morifolium (Ramat.) petals showed that the mechanism of the extractions was related to structural changes in the plant cells. Copyright © 2004 John Wiley & Sons, Ltd. [source] Effect of Plasticizer Concentration and Solvent Types on Shelf-life of Eggs Coated with ChitosanJOURNAL OF FOOD SCIENCE, Issue 4 2006Su Hyun Kim ABSTRACT:, Effects of plasticizer concentrations (0, 0.5, 1.0, 1.5, and 2.0% glycerol) and solvent types (1% acetic and 1% lactic acid) on internal quality of eggs coated with 2% chitosan solution were evaluated during 5 wk of storage at 25 °C. In comparison of plasticizer concentrations, eggs coated with chitosan dissolved in acetic acid containing 2% glycerol showed significant reduction in weight loss compared with the noncoated eggs during 5 wk of storage. At 2% glycerol, the Haugh unit and yolk index values suggested that chitosan-coated eggs can be preserved for at least 3 wk longer than the control noncoated eggs during 5 wk of storage at 25 °C. Use of acetic acid rather than lactic acid as a chitosan solvent was more advantageous in view of shelf-life extension of eggs. [source] | |||||||||||||