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  • 11
    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: Gamma radiation-induced graft copolymerization of either acrylic acid or styrene onto untreated cotton, alkali-treated cotton, and carbamoylethylated cottons having 0.392% N, 0.524% N, 0.725% N, 1.379% and 1.546% N was investigated under different conditions. Moisture regain and dyeability of these substrates before and after copolymerization were also examined. It was found that the graft yield increases by increasing monomer concentration and radiation dose irrespective of the monomer or substrate used. Using water-ethanol mixtures as polymerization media are advantageous for grafting of styrene. With both monomers, however, the graft yield for the modified cottons are substantially higher than untreated and alkali-treated cottons, indicating that the presence of carbamoylethyl in the molecular structure of cotton cellulose affords additional sites for graft copolymerization. Copolymers obtained using acrylic acid show much higher moisture regain that the ungrafted substrates, particularly when the carboxylic groups of the graft were in the sodium form. The opposite holds true for copolymers brought about by grafting with styrene. The color strength of all substrates dyed with a direct or a reactive dye decreases significantly after copolymerization with poly(acrylic acid) prior to dyeing. On the other hand, this copolymerization improves the affinity of the substrates for the basic dye and brings about perceptible shade. Copolymerization of the substrates in question with poly(styrene) improves the color strength of these substrates when dyed with direct, disperse, and basic dyes but decreases the color strength upon dyeing with a reactive dye.
    Additional Material: 11 Ill.
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  • 12
    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 infrared and ultraviolet spectra of poly(vinyl alcohol)(PVA) treated with ferric chloride and zinc chloride were recorded. Careful examination of the infrared spectra revealed that these treatments cause significant changes in the crystallinity of PVA, particularly in the case of the treatment with ZnCl2. The results showed that exposure of untreated and FeCl3-treated PVA to 12 or 28 Mrds results in no observable changes in their ultraviolet and infrared spectral features, whereas exposure of ZnCl2-treated PVA at the same dosages, results in the appearance of an absorption band at 1595cm-1 corresponding to β-diketone groups. It was also found that γ-irradiation of ZnCl2-treated PVA produces a remarkable change in its crystallinity. Moreover, the effect of heat on the spectral features of the ZnCl2-treated PVA was discussed. It was found that the treatment of PVA with ZnCl2 helps in oxidative degradation of PVA.
    Additional Material: 11 Ill.
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  • 13
    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 ultraviolet and infrared spectra of films of PVA treated with Co(11), Ni(11), and Cu(11) and then doped with iodine were studied. The spectra of the films preheated in air at temperatures from 25 to 180°C for 2 h were investigated. The obtained data revealed that treatment of PVA with different concentrations of each of the mentioned metal salts causes profound spectral changes. The analysis of UV spectra showed that the intensity of the band at 280 nm decreases with increasing metal concentration. It was also found that doping with iodine results in an appearance of an additional peak at about 360 nm. Careful examination of the infrared spectra indicated that the crystallinity of the samples depends on the concentration of metals and is affected by temperature treatment.
    Additional Material: 6 Ill.
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  • 14
    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 gamma-induced changes in the structure of Poly(Acrylamide) (PAAm) treated with metal chlorides were investigated by following the corresponding variations in their ultra-violet spectra. Careful examination of UV spectra revealed that irradiation of the specimens results in the appearance of an absorption peak at 275 nm whose intensity depends on the applied dose and the nature of the metal ions. This band is ascribed to the formation of the carbonyl group. The results indicate that the dependence of the intensities of the band at 275 nm on the nature of the metal used provides strong evidence for the formation of metal polymer complexes. It was found that the pretreatment of PAAm with the appropriate concentration of ZnCl2, CoCl2, or NiCl2 reduces the effects of heating and the oxidation effects of γ-irradiation. These results show that these metal ions can be used as stabilizers against thermal degradation of PAAm in the temperature range up to 160°C. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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  • 15
    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: Preparation and some properties of the graft copolymers obtained by radiation-induced graft polymerization of methacrylic acid (MAA) and (acrylonitrile/MAA) comonomer onto polyethylene and polytetrafluoroethylene films, were investigated. The effect of reaction conditions, solvent, monomer, and inhibitor concentration, comonomer composition, and comonomer concentration, on the graft copolymerization process was studied. The grafting process was enhanced in the presence of comonomer (AN/MAA) as compared with individual grafting of MAA or acrylonitrile (AN). The optimum comonomer composition, at which the highest grafting yield was obtained, was found to be (80/20) wt % of (AN/MAA) comonomer. The graft copolymerization of (AN/MAA) comonomer was enhanced in presence of AN due to its higher polarity strength. The electrical and swelling properties of the graft copolymers were greatly affected by the contents of PAN and PMAA graft chains. Mechanical properties of the graft copolymers were significantly changed with the grafting yield.
    Additional Material: 10 Ill.
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  • 16
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aqueous polymerization of methyl methacrylate (MMA) with sodium bisulfite as initiator was carried out in a nitrogen atmosphere with and without inorganic substances like copper metal, cupric and cuprous oxides, and cupric sulfide. It was also done in the presence of organocopper compounds like copper phthalocyanine and copper biphthalocyanine. The catalytic effect of these compounds was studied. Mildly heated cupric sulfide proved to have a small catalytic effect on the polymerization process that may be attributed to the retarding effect of the released elementary sulfur. The catalytic effect of the different copper compounds and the copper metal equivalent contained in them was studied. The polymerization process revealed that cuprous and cupric oxides possess the highest catalytic influence. An attempt was made to investigate the role of the different anions on the polymerization process. It was found that an increase on the concentration of the copper compounds leads to a corresponding increase in the catalytic effect. It was also observed that the behavior of insoluble copper catalysts is different from that of the soluble. The effect of these catalysts on the average molecular weight of the poly(methyl methacrylate) (PMMA) produced was also examined.
    Additional Material: 3 Ill.
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  • 17
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some properties of the membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene-perfluorovinyl ether) copolymer (PFA) films have been investigated. The dimensional change caused by grafting and swelling behavior, water uptake, electrical conductivity, and mechanical properties of the grafted films were found to increase as the grafting proceeds. The influence of the preparation conditions (such as preirradiation dose, monomer concentration, grafting temperature, and film thickness) on those properties was studied. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions, except at higher monomer concentration (〉40 wt %). The electric conductivity and mechanical properties for the membranes obtained at higher AAc concentrations were lower than those obtained at lower ones. Analysis by x-ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the central part with progressive diffusion of monomer to give finally homogeneous distribution of the electrolytes in the whole bulk of the polymer. The membranes show good electrochemical and mechanical properties which make them acceptable for practical use as cation-exchange membranes.
    Additional Material: 12 Ill.
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  • 18
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die mittleren relativen Molekülmassen von Poly(methlmethacrylaten), die durch mit Natriumbisulfit initiierte heterogene Polymerisation von Methylmethacrylat erhalten wurden, folgen den gleichen Gesetzmäßigkeiten wie bei der homogenen Polymerisation. Die in der Monomer- und Wasserphase sowie in der Grenzfläche gebildeten Polymere wurden hinsichtlich ihrer Polydispersität mittels Dünnschichtchromatographie untersucht.
    Notes: The average molecular weights of poly(methyl methacrylate)s obtained in heterogeneous polymerization of methyl methacrylate using sodium bisulfite as initiator were found to obey the same laws applied in homogeneous polymerization. The poly(methyl methacrylate)s formed in the monomer and water phases and the polymer formed at the interphase were investigated by thin layer chromatography with respect of their polydispersities.
    Additional Material: 1 Ill.
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  • 19
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diffusion-free radiation graft polymerization of styrene onto polyethylene has been studied. The grafting rate shows a dependence on monomer which is far different than what has been assumed. Further, the dependence on monomer changes with increasing dose rate as does the dependence of grafting rate on radiation dose rate. Three different regions of behavior are defined: (1) a region of low dose rate where the grafting rate is 1/2-order in dose rate and 3/2-order in monomer; (2) a region of intermediate dose rate where the grafting rate is intermediate between 1/2-and zero-order in dose rate and 5/2-order in monomer; and (3) a region of high dose rate, where the grafting rate is independent of dose rate and at least 5/2-order in monomer. Various possible mechanisms responsible for these effects are discussed, including the effects of viscosity on the initiation and termination reactions, the possibility of ionic graft polymerization, and energy transfer.
    Additional Material: 5 Ill.
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  • 20
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radiation-initiated graft polymerization of styrene onto polyethylene was studied to determine whether energy transfer to diluent was responsible for the previously observed high orders of dependence of the grafting rate on monomer concentration. n-Octane was used as the diluent instead of benzene. If energy transfer from excited polyethylene to benzene were present, it should not be with n-octane. The percent swelling of polyethylene by various n-octane-styrene mixtures was determined. The compositions of various n-octane-styrene mixtures absorbed inside polyethylene were determined by ultraviolet and refractive index measurements and found to be richer in styrene than the corresponding mixtures in which the polyethylene had been placed. The graft polymerization rates were determined at 0.000761, 0.0371, and 0.213 Mrad/hr and plotted against the inside styrene concentrations on a log-log scale to yield the kinetic orders of dependence of rate on monomer as 2,3, and 3, respectively. It was concluded that energy transfer to diluent was not responsible for the high-order dependence observed.
    Additional Material: 4 Ill.
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