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  • Physics  (6)
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  • 1
    Digitale Medien
    Digitale Medien
    Radiation-induced grafting in the polyethylene-styrene system and differential thermal analysis of the grafted samples (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 3181-3192 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The graft polymerization of styrene onto high-density polyethylene films was carried out by γ-irradiation in the vapor phase. Two methods were used for grafting in these experiments: a preirradiation method and a simultaneous irradiation method. The effects of these grafting methods on the reaction mechanism of grafting and on the properties of the grafted samples were investigated. The amounts of styrene homopolymer in the grafted samples is under 2% in the case of the preirradiation method and above 10% in the case of the simultaneous irradiation method. The activation energies were calculated to be 18 kcal/mole for grafting in the preirradiation method and 15 kcal/mole for weight increase of polyethylene films in styrene vapor. The difference in the dimensional expansion between in the direction of stretching and the direction prependicular to it is smaller with preirradiation grafting than with grafting by the simultaneous irradiation method. Differential thermal analysis of the grafted films shows an endothermic peak due thermal decomposition which decreases gradually from 450°C to 415°C with increase in degree of grafting from 30 to 60%. The lowering of this peak temperature appears at a lower degree of grafting when the preirradiation method is used. On the basis of these results, it is concluded that the reaction rate of radiation-induced grafting in the vapor phase depends closely upon the processes of adsorption, dissolution, and diffusion of styrene monomer in polyethylene films; in the case of simultaneous irradiation method, the reaction proceeds comparatively uniformly in the amorphous region, while in the case of the preirradiation method, the reaction proceeds mainly at the boundary of the crystalline and amorphous regions.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1973.170111212
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  • 2
    Digitale Medien
    Digitale Medien
    Kinetic approach to radiation-induced grafting in the polyethylene-styrene system (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 2729-2739 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: To investigate the mechanism of radiation-induced grafting in this system, the increase of monomer concentration in the polyethylene film in styrene vapor was evaluated by measuring the weight increase and formulated to be V([M∞] - [M]). The decay of radical concentration was also measured by ESR and the rate constant of the decay was determined. The alkyl type radical was affected only a little by styrene, while the allyl type radical was much affected by styrene. A new computer investigation method was proposed to clarify the reaction mechanism. The data obtained were substituted into differential equations and used to calculate the pattern of increase of the degree of grafting for the preirradiation method with reaction in the vapor phase. Results of these calculations suggest that only allyl type radicals induce grafting reactions and that the grafting reaction seldom occurs in the region of grafted polystyrene.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1974.170121203
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  • 3
    Digitale Medien
    Digitale Medien
    Kinetic approach to radiation-induced grafting in the polyethylene-styrene system. IV. Comparison between high density polyethylene and low density polyethylene (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 1689-1696 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The investigation method reported in earlier articles was applied to preirradiation methods of the reaction of low-density polyethylene (LDPE) in liquid and vapor and compared with high-density polyethylene (HDPE). Monomer concentrations during reactions and monomer feed rates were determined gravimetrically. Increasing patterns of the degree of grafting were obtained and compared. Monomer concentration during the reactions was lower in LDPE than HDPE and radical decay was more rapid in LDPE. A model calculation was applied to this experiment and a schematic explanation was attempted. The differences between the reaction mechanisms of HDPE and LDPE are explained.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1981.170190709
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  • 4
    Digitale Medien
    Digitale Medien
    Kinetic approach to radiation-induced grafting in the polyethylene-styrene system. II (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 2887-2894 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The investigation method reported in the previous paper was applied to four reaction methods: preirradiation method with reaction in liquid monomer, preirradiation method with reaction in monomer vapor, simultaneous irradiation method in liquid, and simultaneous irradiation method in vapor. The increasing patterns and values of the degree of grafting experimentally obtained roughly agreed with those calculated by using the same rate constants. At high monomer concentration, the rate of grafting was small; at low monomer concentration, the rate of grafting was large. Strictly speaking, the data by simultaneous irradiation method were somewhat larger than those by calculation. Two additional factors, as homopolymerization and the grafting from the radicals formed on the grafted polystyrene, were considered and discussed. The rate constants obtained were also discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1976.170141205
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  • 5
    Digitale Medien
    Digitale Medien
    Kinetic approach to radiation-induced grafting in the polyethylene-styrene system. III (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 1539-1548 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The method of investigation reported in previous papers was applied to preirradiation methods of reaction in vapor and in liquid. The absorption dose was varied from 2 to 0.1 Mrad. The monomer concentrations during reactions were determined gravimetrically. The patterns of increase of the degree of grafting did not change as the dose was varied in the liquid but changed considerably with dose in the vapor. The monomer concentration during the reaction did not vary with dose in the liquid but did so in the vapor. A model calculation was applied and improved to make the monomer concentration agree with that in the experiment. An attempt was made to describe the mechanism involved. There were some differences between the calculated values and the experimentally obtained ones, but the outline of the reaction mechanism was explained satisfactorily.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1978.170160708
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  • 6
    Digitale Medien
    Digitale Medien
    Kinetic approach to radiation-induced grafting in the polyethylene-styrene system. V. The behavior of initiator radicals (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 15-23 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: With high-density polyethylene (HDPE) and low-density polyethylene (LDPE) films the grafting reactions were performed by the preirradiation method. By holding the total absorption dose constant irradiation time was varied. The initial rate of grafting decreased with irradiation time. The relative concentration of alkyl radical in the polyethylene film also decreased with irradiation time, but the relative concentration of allyl increased. The differences in the ESR spectrum before and after the introduction of styrene indicate that the allyl-type radical reacted with styrene. To elucidate these results the allyl radical in the amorphous region was considered.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.170200102
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