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  • 1
    Electronic Resource
    Electronic Resource
    A catalytic membrane reactor: its performance in comparison with other types of reactors (1990)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 29 (1990), S. 232-238 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00098a013
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  • 2
    Electronic Resource
    Electronic Resource
    Catalytic membrane for simultaneous chemical reaction and separation applied to a dehydrogenation reaction (1988)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 27 (1988), S. 1136-1142 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00079a008
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  • 3
    Electronic Resource
    Electronic Resource
    Pervaporation of ethanol-water mixtures through poly(vinyl alcohol-g-acrylic acid) membranes prepared by use of Fenton's reagent in grafting (1995)
    Springer
    Journal of polymer research 2 (1995), S. 47-53 
    Details
    ISSN: 1572-8935
    Keywords: Pervaporation ; Ionic crosslinking ; Poly(vinyl alcohol) ; Poly(acrylic acid) ; Redox initiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Ionic crosslinking of the ferric ions and the carboxylic groups in the poly(vinyl alcohol-g-acrylic acid) (poly(VA-g-AA)) membranes improves the size screening effect in the pervaporation of ethanol-water separation. In the grafting polymerization of acrylic acid monomer onto poly(vinyl alcohol) (PVA), ferric ions are remained in the polymer membranes as the Fenton's reagent(Fe2+-H2O2) is used to initiate the reaction. Completely reversed trends in terms of the degree of swelling, the pervaporation selectivity, and the flux of permeates are obtained depending on that the ferric ions are present or absent in the membranes. The degree of swelling decreases, the pervaporation selectivity increases, and the flux decreases as the grafting percentage increases for the membranes containing ferric ions. The degree of swelling and the flux of permeates increase but the pervaporation selectivity is reduced as the grafting percentage increases for the membranes which were washed with acid to remove ferric ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01493433
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  • 4
    Electronic Resource
    Electronic Resource
    Solute transport in poly(2-hydroxyethyl methacrylate) hydrogel membranes (1995)
    Springer
    Journal of polymer research 2 (1995), S. 71-82 
    Details
    ISSN: 1572-8935
    Keywords: Swelling ; Diffusion ; Permeation ; Controlled drug release ; Mass transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The swelling, permeation, and release characteristics for benzoic acid, caffeine, propranolol hydrochloride, and diclofenac sodium in crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels were examined. Increasing polymer crosslinking density resulted in decreases in the degree of swelling, drug loading, the diffusivity of solute in the hydrogels, and in the rate of drug release. Diclofenac sodium led to an abnormally large degree of swelling as the maximum value is given as 6.5, while the highest for the other three was 1.07. That the logarithmic drug diffusivity was proportional to the reciprocal of hydration indicates that the free volume theory accounts for the transport of solute in the gels. Increasing the concentration resulted in increases in the diffusivities, solubilities, and permeabilities of the solutes in the hydrogels. The drug release kinetics from most wet hydrogel samples can be well-fitted by a Fickian diffusion model. Near zero-order release is observed only for dry samples with caffeine of low loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01493206
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  • 5
    Electronic Resource
    Electronic Resource
    Sorption and permeation properties of water and ethanol vapors in poly[bis(trifluoroethoxy)phosphazene] (PTFEP) membranes (1999)
    Springer
    Journal of polymer research 6 (1999), S. 91-98 
    Details
    ISSN: 1572-8935
    Keywords: Membrane ; Polyphosphazene ; Permeability ; Solubility ; Diffusivity ; Solution-diffusion model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The permeability and solubility for water and ethanol in PTFEP membranes were determined experimentally, and the data were analyzed by the solution-diffusion model. The permeability for water and ethanol ranged from several hundreds to several thousands Barrers, and they increased exponentially with the vapor activity and increased with temperature. At the same temperature and vapor activity, the permeability ratio between water and ethanol ranged from 5.7 to 2.3, and it decreased as the vapor activity increased. The sorption isotherms for water and ethanol were fitted by the Henry’s law relationship. The solubility decreased as the temperature increased so that the heat of sorption for both water and ethanol was negative. The solubility for water was more than twice the solubility for ethanol. The solubility seems to be inversely proportional to the molecular size of the penetrants in such a system. The solubility ratio between water and ethanol is smaller than their molecular volume ratio possibly due to the slightly stronger nonpolar interaction and the higher degree of plasticization in the ethanol-polymer system. The diffusivity for water and ethanol ranged from 10−8 to 10−7 cm2/s, and the values for water were larger than those for ethanol at the same temperature and vapor activity. The diffusivity for water and ethanol also increased exponentially with the vapor activity. The diffusivities for water and ethanol increased with temperature and their activation energies of diffusion were very similar possibly due to the same energy characteristic of polymer main chain movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10965-006-0075-2
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  • 6
    Electronic Resource
    Electronic Resource
    Positronium Chemistry in Polymeric Membrane Systems (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 607 (Nov. 2008), p. 1-8 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Positron and Positronium chemistry has been pursued and advanced by many scientists and engineers in both fundamental understanding of Positronium atom and its applications to chemical and polymeric systems during the last decade. This paper presents our recent results from collaborative investigations of positron annihilation in polymeric membranes. Future perspectives of applying Positronium chemistry to membrane science and technology and other related disciplines of nanotechnology, chemical engineering, materials science, energy research, molecules with positrons, biological and medical sciences appear to be promising
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.607.1.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Curing kinetics of the synthesis of poly(2-hydroxyethyl methacrylate) (PHEMA) with ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1873-1889 
    Details
    ISSN: 0887-624X
    Keywords: free-radical polymerization ; kinetics ; hydrogel ; thermoset ; crosslinking ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An experimental study was carried out to investigate the effect of ethylene glycol dimethacrylate (EGDMA, as a crosslinking agent) content on the curing kinetics of the polymerization of 2-hydroxyethyl methacrylate (HEMA), using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). EGDMA may cause a crosslinking-facilitated gel effect which reduces the termination rate of living free radicals and enhances the overall reaction rate, but it may also induce a diffusional resistance for the reactants so that some free monomers are trapped and pendant vinyl groups are prohibited from reaction by the crosslinked structure. At higher content of EGDMA, the later effect becomes predominant, and the reaction rate and the final conversion are limited. The exothermic peak of the curing reaction tends to carry a shoulder and then split into two peaks as the amount of EGDMA is increased, possibly due to a later reaction of the trapped monomers and pendant vinyls. The heat of reaction measured by DSC in the scanning mode is 61.2 kJ/mol C=C. The activation energy (E) of the curing reaction ranges from 56.5 to 78.3 kJ/mol C=C depending on the EGDMA content and the type of operation. The diffusion-limited reaction rate and the different thermal history experienced in the nonisothermal and isothermal curing can result in variations of the results in the activation energy measurement. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1873-1889, 1997
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Sorption/desorption properties of ethanol, toluene, and xylene in poly(dimethylsiloxane) membranes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 1797-1804 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sorption/desorption kinetics and sorption equilibria have been determined for ethanol, toluene, and xylene vapors in a poly(dimethylsiloxane) membrane containing about 32 wt % silica resin at 25°C. Dependence of diffusion coefficient on vapor activity and sorption isotherms have been compared to identify the transport mechanisms of those penetrants in the PDMS membrane. The analysis of Zimm-Lundberg clustering functions showed that all three penetrants had a tendency to form clusters and ethanol molecules might be immobilized by the residual silanol groups within the silica resin in the membrane. The diffusion coefficient of toluene was roughly constant and that of xylene slightly decreased as increasing the vapor activity due to the competing effects of penetrant clustering and solvent swelling of polymer. The diffusion coefficient of ethanol versus activity exhibited a maximum due to the effects of ethanol immobilization and cluster formation. The freevolume effect by solvent swelling to diffusion was obscured by either penetrant clustering or immobilization for the three penetrant-polymer systems. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070511014
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  • 9
    Electronic Resource
    Electronic Resource
    Immobilization of α-Amylase to Temperature-Responsive Polymers by Single or Multiple Point Attachments (1997)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 69 (1997), S. 421-428 
    Details
    ISSN: 0268-2575
    Keywords: N-isopropylacrylamide ; temperature-sensitive ; α-amylase ; LCST ; immobilized enzyme ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: --Temperature-responsive N-isopropylacrylamide (NIPAAm) polymer (PNIPAAm) with a free carboxyl functional end group and a copolymer (NIPNAS) of NIPAAm and N-acryloxysuccinimide (NAS) were synthesized and used for immobilization of α-amylase. The enzyme forms covalent bonds with the former polymer by single point attachment and with the latter polymer by multiple point attachment. Such a difference influences the enzyme activity and properties of the immobilized enzymes. The polymers are temperature-sensitive with lower critical solution temperatures (LCST) of 34·7 and 36·0°C for NIPNAS and PNIPAAm, respectively. The immobilized enzyme exhibited an LCST of 35·5°C for NIPNAS-amylase and 37·1°C for PNIPAAm-amylase. They precipitated and flocculated in aqueous solution above the LCST and redissolved when cooled below that temperature. The activity of the immobilized enzyme depended on the pH of the coupling buffer, with 8·0 being the optimum value. The specific activities of the immobilized enzymes were 87% and 108% compared with that of free enzyme with soluble starch as the substrate for NIPNAS-amylase and PNIPAAm-amylase, respectively. By characterizing the properties of the immobilized enzymes and comparing with those of free enzyme, no diffusion limitation of substrate was found for the immobilized enzymes and they are more thermal stable than the free enzyme. Within the two immobilized enzymes, NIPNAS-amylase showed better thermal stability and reusability. Repeated batch hydrolysis of soluble starch can be carried out efficiently with the immobilized enzymes by intermittent thermal precipitation and recycle of the enzyme. © 1997 SCI.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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