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  • Articles: DFG German National Licenses  (38)
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  • Articles: DFG German National Licenses  (38)
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  • 21
    Electronic Resource
    Electronic Resource
    Study on radiation grafting of acrylic acid onto fluorine-containing polymers. II. Properties of membrane obtained by preirradiation grafting onto poly(tetrafluoroethylene) (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 3871-3883 
    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: Some properties of the membranes obtained by the preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene) (PTFE) film have been studied. The dimensional change by grafting and swelling, water uptake, electric conductivity, and mechanical properties of the grafted PTFE films were measured and were found to increase as the grafting proceeds. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions except higher monomer concentration (80 wt %). The electric conductivity and mechanical properties of the membranes at 80 wt % monomer concentration is lower than those at a lower monomer concentration. The results suggest that the membranes obtained at 80-wt % acrylic acid solution have a somewhat heterogeneous distribution of electrolyte groups as compared with those prepared at a monomer concentration less than 60 wt %. X-ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the center with progressive diffusion of monomer to give finally the homogeneous distribution of electrolyte groups. The membranes show good electrochemical and mechanical properties which make them acceptable for the practical uses as cation exchange membrane.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070261132
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  • 22
    Electronic Resource
    Electronic Resource
    The study on radiation grafting of acrylic acid onto fluorine-containing polymers. III. Kinetic study of preirradiation grafting onto poly(tetrafluoroethylene-hexafluoropropylene) (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 535-543 
    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: A kinetic study has been made on the preirradiation grafting of acrylic acid (AAc) onto poly(tetrafluoroethylene-hexafluoropropylene) (FEP) film. The effect of grafting conditions was investigated. The dependencies of the grafting rate on preirradiation dose and monomer concentration were found to be 0.58 and 1.25 order, respectively. The overall activation energy for the graft polymerization was 7.4 kcal/mol. The final degree of grafting increased with preirradiation dose and monomer concentration and slightly decreased as the grafting temperature was elevated. The relationship between the grafting rate and film thickness gave a negative first-order dependency, which is in agreement with that obtained for polytetrafluoroethylene - AAc grafting system. It was reasonably concluded that this grafting proceeds from the surface to the center of film with progressive monomer diffusion through the grafted layer which swells in the monomer solution.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270217
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  • 23
    Electronic Resource
    Electronic Resource
    Graft polymerization of acrylic acid onto polyethylene film by preirradiation method. I. Effects of preirradiation dose, monomer concentration, reaction temperature, and film thickness (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1033-1041 
    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: Low-and high-density polyethylenes were irradiated by electron beams with dose of 2-50 Mrad and then immersed in aqueous solution of acrylic acid (monomer concentration from 30 to 100 wt %) for 10 min-5 h at a temperature of 25-40°C. The degree of grafting increases with time and levels off. High density polyethylene shows lower grafting rate and higher final % grafting in compared with low-density polyethylene. Both grafting rate and final % grafting increase with total dose of preirradiation, but show some saturation at high doses. The highest grafting rate was observed at 60 wt % of monomer concentration where the grafted polyethylene swells to the largest extent in the monomer mixture. Apparent activation energies for the grafting are 19.6 and 27.3 kcal/mol for low- and high-density polyethylenes, respectively, reflecting the proces of monomer diffusion in the film. Grafting rate decreases with increasing film thickness. Graft polymerization starts on the surface of the film and proceeds to the inner part with monomer diffusion through the grafted layer.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270322
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  • 24
    Electronic Resource
    Electronic Resource
    Graft polymerization of acrylic acid onto polyethylene film by preirradiation method. II. Effects of oxygen at irradiation, storage time after irradiation, mohr's salt, and ethylene dichloride (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1043-1051 
    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: In the grafting of acrylic acid onto polyethylene by preirradiation method, the irradiation in air gave a higher rate of grafting than in N2, since the diffusion rate of monomer is larger for less crosslinked polyethylene. The rate of grafting decreased with increasing time of storaging polyethylene because of the decay of trapped radicals. The effects of storage conditions on the grafting activity was reasonably interpreted by assuming that grafting is predominantly controlled by both concentration of trapped radicals and monomer diffusibility in the polymer matrix. Mohr's salt was found to depress the homopolymerization of acrylic acid without marked change of grafting rate. The rate of grafting was increased by the addition of ethylene dichloride due to the increase in monomer diffusion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270323
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  • 25
    Electronic Resource
    Electronic Resource
    The study on radiation grafting of acrylic acid onto fluorine-containing polymers. IV. Properties of membrane obtained by preirradiation grafting onto poly(tetrafluoroethylene-hexafluoropropylene) (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 1465-1479 
    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: Some properties of the membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene-hexafluoropropylene) (FEP) film have been investigated. Swelling behavior, dimensional change by grafting, electric conductivity, and mechanical properties of the grafted films were found to depend largely on the degree of grafting and to increase as the grafting proceeds. These properties were also found to be independent of the preparation conditions such as irradiation dose, grafting temperature, film thickness, and monomer concentration lower than 60 wt %. The electric conductivity of the membranes prepared at lower monomer concentration (lower than 60 wt %) is higher than that prepared at 80 wt % acrylic acid concentration. X-ray microscopy of the grafted film revealed that the grafting proceeds from both surfaces of the film to the direction of center to give finally homogeneous grafting through the whole bulk of film. At lower monomer concentration the homogeneous grafting was achieved at a degree of grafting around 18%, while at 80 wt % acrylic acid it was achieved at a degree of grafting higher than 70%. The homogeneously grafted membranes show good electrochemical and mechanical properties which make them acceptable for practical uses as cation-exchange membranes.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280420
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  • 26
    Electronic Resource
    Electronic Resource
    Gel permeation chromatography of polyoxymethylene (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1927-1942 
    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: Gel permeation chromatography of polyoxymethylene has been studied using N,N-dimethylformamide as the solvent. Polyoxymethylene samples used here are a copolymer of tetraoxane with 1,3-dioxolane and a commercial polyoxymethylene whose molecular weight distributions are moderately broad. Their intrinsic viscosities [η] range from 1.4 to 2.8 dl/g. Factors affecting chromatograms are discussed, and the operating conditions were determined by using the analytical scale GPC. On the basis of these operating conditions, the molecular weight fractionation of polyoxymethylene was carried out by using the preparative scale GPC. It was found that polyoxymethylene can be effectively fractionated to give seven to ten fractions each of them containing the fractionated polymer ranging in weight from 0.2 to 8 mg when 40 mg polymer sample was used for a run of the measurement. The fractionated polymers were also found to have a narrow molecular weight distribution within a single peak, and their Mw/Mn values decrease with increasing molecular weight.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180703
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  • 27
    Electronic Resource
    Electronic Resource
    Iodine-initiated, solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. I. Fundamental study on beaker-scale copolymerization (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 711-722 
    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: The iodine-initiated, solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal has been studied on a beaker scale. It was found that tetraoxane can be easily copolymerized with 1,3-dioxolane by a small amount of iodine as initiator and gives oxymethylene copolymer with excellent thermal stability in a high yield. The copolymerization was largely influenced by the concentrations of iodine, 1,3-dioxolane, and methylal, i.e., the polymerization rate increased with increase not only in iodine but also in 1,3-dioxolane, and the thermal stability and the molecular weight of the copolymer were mainly affected by 1,3-dioxolane and methylal concentration, respectively.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210312
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  • 28
    Electronic Resource
    Electronic Resource
    Iodine-initiated, solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. II. Properties of copolymer obtained by beaker-scale copolymerization (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 723-733 
    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: In order to elucidate the copolymerization mechanism, the properties of the copolymer obtained by the iodine-initiated copolymerization of the tetraoxane-1,3-dioxolane-methylal system have been studied using gas chromatography, microscopy, scanning electron microscopy, differential scanning calorimetry, and gel permeation chromatography. From the behavior of the thermal stability and gas chromatography of the reaction mixture, it was found that reactivity of 1,3-dioxolane with active center is larger than that of tetraoxane, i.e., more than 90% 1,3-dioxolane is consumed at an early stage of the polymerization. The results obtained by microscopy, DSC, and GPC of the copolymer suggested that the copolymerization proceeds from the surface to the center of the tetraoxane crystal as if it were a core model. It was also suggested that the heterogeniety in copolymer properties can be explained not only by heterogeneous dispersion of 1,3-dioxolane in tetraoxane crystal, but also by the difference of reactivity of 1,3-dioxolane with the active center.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210313
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  • 29
    Electronic Resource
    Electronic Resource
    Iodine-initiated, solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. V. Studies on molecular weight distribution of copolymer (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 3383-3394 
    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: The iodine-initiated, solid-state copolymerization of the tetraoxane-1,3-dioxolane-methylal system has been studied by measuring the molecular weight distribution of the copolymer. The molecular weight distribution of the copolymer is found to be strongly dependent on the addition method of the 1,3-dioxolane-methylal solution to tetraoxane. The copolymer obtained by the one-addition copolymerization has a molecular weight distribution curve that shows a very broad distribution, with a discernible shoulder; and the copolymer obtained by the continuous-addition copolymerization has a very sharp curve. Particle size of the copolymer also influences the molecular weight distribution. For the one-addition copolymerization, the larger the particle size of the copolymer, the broader the molecular weight distribution. For the continuous-addition copolymerization, however, the molecular weight distribution is nearly constant regardless of particle size. The dependence of the molecular weight distribution on the polymerization time and the concentrations of iodine, 1,3-dioxolane, and methylal is discussed in detail. These results suggest that this copolymerization system is characterized by a reaction that proceeds from the surface to the center of the tetraoxane crystals.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070231122
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  • 30
    Electronic Resource
    Electronic Resource
    Iodine-initiated, solid-state copolymerization of tetraoxane with 1,3-dioxolane in the presence of methylal. VII. Treatment of copolymer after polymerization (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 3411-3420 
    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: The various procedures for removing the residual reactants and impurities from the polymer particle obtained by the solid-state copolymerization of tetraoxane with 1,3-dioxolane have been examined. The removal of the residual reactants by washing with solvents, such as acetone or water, were very difficult, because the residual reactants are mainly located in the central part of the polymerized particle. By evacuation of the polymeric system just after polymerization, however, the residual reactants were found to be easily eliminated from the polymer particle. It was also found that the polymer degradation caused by the acid impurities formed during polymerization can be prevented satisfactorily by neutralization using gaseous ammonia. On the basis of these findings, the simple process for polyoxymethylene production has been achieved; i.e., it was found that the polymer particle including the residual reactants and impurities can be directly pelletized using a vent-type extruder, immediately after the copolymerization procedure and the ammonia gas treatment, to obtain the polyoxymethylene pellet with an excellent thermal stability and a well controlled molecular weight.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070231124
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