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  • Digitale Medien  (6)
  • Physics  (6)
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  • Digitale Medien  (6)
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  • 1
    Digitale Medien
    Digitale Medien
    Microstructure of polybutadiene catalyzed by alkali metal tert-butoxides and n-butylsodium. II. (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 253-259 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A polybutadiene of high molecular weight was prepared in hydrocarbon solvent by using n-BuNa-tert-BuOM (M = Li, K) as a polymerization initiator. The microstructure of this polymer varied from 35 to 76% of 1,2 content, depending on the type of modifiers. The kinetics of polymerization was not studied, primarily due to the heterogeneous nature of the catalyst. However, other variables, such as the catalyst concentration and temperature, have been studied. The results and mechanistic implications are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1973.170110121
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  • 2
    Digitale Medien
    Digitale Medien
    Anionic polymerization. VI. Effect of polar modifiers on alkylsodium and alkylpotassium polymerization of butadiene (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1771-1777 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It was found that N,N,N′,N′-tetramethylethylene diamine and hexamethyl phosphorus triamide minimize chain transfer reactions in the polymerization of 1,3-butadiene in hydrocarbon solvent with alkylsodium or alkylpotassium initiators. The polymers obtained with alkylsodium initiators had a high molecular weight and high vinyl content at 90-95% conversion. The molecular weight of the polybutadiene made by alkylsodium and alkylpotassium initiators was dependent on the polymerization temperatures and modifier ratios, but the vinyl contents were independent of the modifier ratios. Vinyl contents of alkylpotassium-initiated polymers showed a slight dependency on polymerization temperature; the vinyl contents of alkylsodium-initiated polymers were independent of temperature. Addition of lithium tert-butoxide and potassium tert-amylate to these initiators in the presence of the modifiers affected the molecular weight but not the microstructure.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1979.170170618
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  • 3
    Digitale Medien
    Digitale Medien
    Polymerization of butadiene with lithium morpholinide initiators (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1847-1848 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1979.170170628
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  • 4
    Digitale Medien
    Digitale Medien
    Anionic polymerization. III. Polymerization of butadiene with alkali metal alkoxide-modified alkali metal system (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 573-581 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A high molecular weight polybutadiene was prepared in hexane solvent by using alkali metal (Li, Na, K) and metal tert-butoxide (Li, Na, K) as a polymerization initiator. The microstructure of polybutadiene varies, depending on the type of modifiers and polymerization and temperatures. The results and mechanistic implications of this study are discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1976.170140306
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  • 5
    Digitale Medien
    Digitale Medien
    Anionic polymerization. IV. Effect of crown ethers on alkylsodium initiator (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 14 (1976), S. 583-589 
    Details
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polymerization of butadiene and copolymerization of butadiene-styrene with alkylsodium catalyst modified by crown ethers in hydrocarbon solvent has been investigated. This catalyst system produced polybutadiene of high viscosity (2.0-5.0) and high vinyl content (80%) in high conversion (75-95%). These results are in contrast to those obtained with aliphatic ether-modified alkylsodium polymerization which typically gives products of low molecular weight and at low conversion. The copolymerization of butadiene-styrene with alkylsodium catalyst modified by crown ethers gave a copolymer which did not contain block styrene. Although the copolymer did not contain block styrene, there was an unusually high level of incorporation of styrene in the copolymer at low conversion. This behavior is quite different from either modified organolithium or unmodified organosodium initiators, in which the styrene is uniformly and randomly incorporated along the chain.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1976.170140307
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  • 6
    Digitale Medien
    Digitale Medien
    Effect of alkoxides on chain termination and chain transfer of sodium-catalyzed polybutadienePaper presented in part at the Symposium on Anionic Polymerization at the 1st Akron Summit Polymer Conference, Akron, Ohio, June 18-19, 1970.1 (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 2493-2502 
    Details
    ISSN: 0449-296X
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of butadiene with n-butylsodium or metal alkoxide-modified n-butylsodium was studied. A loss of “live ends” was observed when the polymerization of butadiene-1,3 with n-butylsodium was conducted in hexane solvent. This occurs, presumably, by elimination of NaH or Na metal in the allylic system. Similar results were obtained when the polymerization was carried out in the presence of sodium-tert-butoxide-modified n-butylsodium. However, the modification of n-butylsodium by lithium or potassium tert-butoxide in the butadiene-1,3 polymerization showed no loss of live ends for a period of two weeks. The results and an explanation are discussed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1971.150090906
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