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  • 1
    Electronic Resource
    Electronic Resource
    Radiation-induced emulsion polymerization of ethylene. III. Emulsion polymerization with ammonium perfluorooctanoate as the emulsifier (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 105-120 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radiation-induced emulsion polymerization of ethylene with ammonium perfluoro-octanoate as an emulsifier was studied in order to elucidate the effect of the number of polymer particles. Owing to the stable structure of the emulsifier from a radical attack, no C—F bond was detected in the polyethylene as expected. The polyethylene produced was mostly gel containing a small amount of low molecular weight polyethylene. This may be attributable to chain transfer to the polyethylene. The effects of dose rate and of concentration of the emulsifier were determined without considering the chain-transfer reaction to the emulsifier. By considering the escape of the radical which is produced by chain transfer to the monomer from the polymer particle to the aqueous phase at the steady state, the following equation is derived: \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{R_p }}{I} = \frac{{K_i K_p ^2 [{\rm N}_{\rm T} ]}}{{2K_0 \alpha R_p }} - \frac{{K_i K_p }}{{K_{0\alpha } }} $$\end{document} The experimental results could be explained by this equation, and the apparent rate constants were obtained.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120110
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  • 2
    Electronic Resource
    Electronic Resource
    Emulsifier-free emulsion polymerization of tetrafluoroethylene by radiation. I. Effects of reaction conditions on the polymerization rate and polymer molecular weight (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 2931-2944 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radiation-induced emulsifier-free emulsion polymerization of tetrafluoroethylene was carried out at an initial pressure of 2-25 kg/cm2, temperature of 30-110°C, and under a dose rate of 0.57 × 104-3.0 × 104 rad/hr. The rate of polymerization was shown to be proportional to 1.0 and 1.3 powers of the dose rate and initial pressure, respectively, and is maximal at about 70°C. The molecular weight of polytetrafluoroethylene (PTFE) lies in the range of 105-106, increases with reaction time in the early stage of polymerization, and is maximal at 70°C but is almost independent of the dose rate. An interesting discovery is that PTFE, a hydrophobic polymer, forms as a stable latex in the absence of emulsifier. When PTFE latex coagulates during polymerization under certain conditions, the polymerization rate decreases, probably because polymerization proceeds mainly on the polymer particle surface. The observed rate acceleration and successive increase in polymer molecular weight may be due to slow termination of propagating radicals in the rigid PTFE particles.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.170161118
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  • 3
    Electronic Resource
    Electronic Resource
    Emulsifier-free emulsion polymerization of tetrafluoroethylene by radiation. II. Effects of reaction conditions on polymer particle size and number (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 111-127 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The size, distribution, and number of PTFE particles formed by radiation-induced emulsifier-free polymerization were measured by electron microscope and automatic particle analyzer (centrifugation method). From the electron micrographs we found that the particles are formed within 5 min. The change in the number of polymer particles (np) with reaction time (t) depends on the relative concentration of growing polymer chains to stabilizing species produced by the radiolysis of water and monomer; that is, it was governed by TFE pressure/dose rate ratio and classified into three cases: case I, dnp/dt = 0 (e.g., at 3 × 104 rad/hr and 20 kg/cm2); case II, dnp/dt 〈 0 (e.g., at dose rate below 1.9 × 104 rad/hr and 20 kg/cm2); case III, dnp/dt 〉 0 (e.g., at 3 × 104 rad/hr and 2 kg/cm2). The polymer molecular weight above 106 is almost independent of the particle size. The polymerization loci are mainly on the surface of polymer particles dispersed in the aqueous phase in cases I and II except in the initial stage. In case III new particles are formed successively during polymerization. Therefore the polymerization loci are mainly in the aqueous phase. Especially in case I, we concluded that after the generation of particles the propagation proceeds mainly on the surface of polymer particles like the core shell model proposed by Granico and Williams.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.170170111
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  • 4
    Electronic Resource
    Electronic Resource
    Emulsifier-free emulsion polymerization of tetrafluoroethylene by radiation. III. Simultaneous formation of hydrofluoric acid (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 129-138 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simultaneous formation of hydrofluoric acid (HF) in the radiation-induced polymerization of tetrafluoroethylene (TFE) was investigated. HF concentration in PTFE latex was determined mainly by conductometric titration with 0.01 and 0.001N NaOH. The amount of HF formed is almost independent of agitation speed and the amount of n-hexadecane added and is maximal at ca. 70°C corresponding to the rate of polymerization.The rate of HF formation increases with the initial pressure of TFE monomer and dose rate and decreases with polymerization or TFE consumption. This fact suggests that HF is formed mainly by TFE reactions and not by the degradation of PTFE.The mechanism of HF formation in this reaction system in the absence of oxygen is shown in the following two schemes: scheme I is the reaction of TFE with primary radicals (OH·, H·, eaq-) from the radiolysis of water; scheme II is the reaction of water with the species from the radiolysis of TFE. On the assumption that HF is formed only according to scheme I, the G value of HF formation G(HF)calc can be calculated as 11.25. All observed G values G(HF)obs are larger than G(HF)calc. When the polymerization is carried out at 20 kg/cm2 under various dose rates, G(HF)obs increases with the dose rate. When the polymerization is carried out at 3.0 × 104 rad/hr under various pressures, G(HF)obs decreases with the decrease in pressure from 20 to 2 kg/cm2 and is fairly close to G(HG)calc at 2 kg/cm2. This indicates that HF formation is due mainly to scheme II at high pressure (in the presence of enough TFE) and to scheme I as the pressure is lowered.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.170170112
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  • 5
    Electronic Resource
    Electronic Resource
    Emulsifier-free emulsion polymerization of tetrafluoroethylene by radiation. V. Effect of reaction conditions on the stability of polytetrafluoroethylene latex (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 503-516 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stability of PTFE latex prepared in the absence of emulsifier by radiation-induced polymerization was investigated by electrophoresis and conductometric titration. The storage stability depends on total dose rather than dose rate, and the stable latex can be obtained in the region log D 〉 0.026 V1 - 0.6, where D is the total dose (104 rad) and V1 is a polymer concentration in latex (g/liter). The stability increases only during polymerization in the presence of enough TFE monomer. The ζ potential of the latex particles lies in the region from -25 to -50 mV in an as-polymerized state (near pH 3) and from -50 to -65 mV at pH 10. The number of carboxyl end groups and surface charge density were examined by conductometric titration with NaOH and calculation from the G values of radiolysis of water. All the surface charge densities measured by conductometric titration are larger than those calculated from the G values. These results suggest that some acids have been formed on the surface of the particles. The acids may be the carboxyl end groups of polymer chains or hydrofluoric acid (HF) adsorbed on the surface. PTFE particles prepared in this polymerization system are stabilized mainly due to the carboxyl end groups and adsorptions of OH- and HF on the particles.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.170170220
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation of emulsifier-free polyethylene latecies by radiation polymerization (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 13 (1975), S. 369-375 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.130130611
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  • 7
    Electronic Resource
    Electronic Resource
    Radiation-induced emulsion polymerization of ethylene. I. Effect of reaction conditions on the polymerization (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 83-92 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of reaction conditions on the rate of radiation-induced emulsion polymerization of ethylene was studied by use of a 500-ml autoclave. Among various kinds of emulsifiers, a series of potassium salts of fatty acids gave high rates of the polymerization. The polymerization was inhibited by the presence of oxygen, but the rate of polymerization followed by the induction period was not influenced by the initial presence of oxygen. Stirring rate and the monomer: water ratio did not affect the rate of polymerization. The rate of polymerization was maximum at about 80°C, and number-average molecular weight was influenced by the temperature in a similar manner as the rate of polymerization. This suggests that the change of mobility of propagating radical in the polymer particle changes the rate of termination reaction. The rate of polymerization was proportional to the 1.7 power of the reaction pressure.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120108
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  • 8
    Electronic Resource
    Electronic Resource
    Radiation-induced emulsion polymerization of ethylene. II. Effect of potassium myristate concentration and dose rate on the rate of polymerization in connection with polymer properties, kinetics, and mechanism (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 93-103 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radiation-induced emulsion polymerization of ethylene with potassium myristate as an emulsifier was studied in connection with the kinetics and the mechanism. The molecular weight of polymer was relatively low, of the order of 103, when a sufficient amount of emulsifier was used. However, polyethylene gel was produced in the absence of a sufficient amount of emulsifier. The rate of polymerization was proportional to the 0.5 power of dose rate and increased slightly with increasing emulsifier concentration. The rate of seeded polymerization followed a similar trend to that for conventional polymerization. Kinetic analysis of these results suggests that the escape of radicals produced by chain transfer of propagating radical with the emulsifier and the monomer from polymer particles into the aqueous phase plays an important part in the rate of polymerization. The melting temperature and the crystallinity of the polymer significantly decreased with increasing polymerization temperature in the range 40-60°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120109
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  • 9
    Electronic Resource
    Electronic Resource
    Radiation-induced emulsion polymerization of tetrafluoroethylene (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 2249-2259 
    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 radiation-induced emulsion polymerization of tetrafluoroethylene was carried out with the use of ammonium perfluorooctanoate as an emulsifier at an initial pressure of ca. 30-35 Kg/cm2. The polymerization rate was shown to be proportinal to about the 0.8 power of the dose rate in the range of 2 × 104 to 105 R/hr and to be almost independent of emulsifier concentration. The molecular weight of the polymer lies in the range of 104 to 105, increases with reaction time at the initial stage, and decreases with emulsifier concentration, but is independent of the dose rate from 2 × 104 to 6 × 104 R/hr. If the emulsifier is not used, a polymer with a molecular weight as high as 1.8 × 106 to 2 × 107 is obtained. Apparently, the emulsifier and its radiolysis products act as chain transfer agents. Postirradiation polymerization was found to take place with the formation of products with increased molecular weight.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180804
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of cationic flocculant by radiation-induced copolymerization of methyl chloride salt of N,N-dimethylaminoethyl methacrylate with acrylamide in aqueous solution (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 1713-1721 
    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 radiation-induced copolymerization of the methyl chloride salt of N,N-dimethylaminoethyl methacrylate (DMAEM·MC) with acrylamide (AAm) was used to prepare a cationic polymer flocculant. The polymerization rate increased with increasing dose rate, polymerization temperature, monomer concentration and mole fraction of AAm in the monomer mixture. The molecular weight of the copolymer was also found to increase with monomer concentration and mole fraction of AAm, but at high concentration and fraction of AAm, intermolecular crosslinking tends to occur during the polymerization to form water-insoluble copolymer. A water-soluble copolymer having various molecular weights and cationic strengths can be synthesized by selecting suitable reaction conditions; i.e., this radiation process can provide a much higher molecular weight copolymer with a wide range of cationic strength. The flocculation effect was evaluated using sludge from wastewater of sugar manufacture. It was found that the radiation-polymerized copolymer DMAEM·MC-AAm has an excellent flocculation effect.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240711
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