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  • Polymer and Materials Science  (9)
  • Keywords: fermentation; vegetable oils; tetracycline; Streptomyces aureofaciens  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Vegetable oils in fermentation: beneficial effects of low-level supplementation (1998)
    Springer
    Journal of industrial microbiology and biotechnology 21 (1998), S. 203-207 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: fermentation; vegetable oils; tetracycline; Streptomyces aureofaciens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To evaluate their potential to enhance fermentation performance, vegetable oils were investigated in a model tetracycline fermentation. With sucrose as the carbon source, the fermentation efficiency of Streptomyces aureofaciens (ATCC 10762) was enhanced by the inclusion in the medium of low levels of vegetable oil. Soybean and sunflower oils significantly improved the rate of sucrose consumption and tetracycline production suggesting that oil is an excellent adjuvant for improving fermentation productivity. For optimum benefit, the dosage level was critical. Little difference was observed between crude and refined oils. These data contribute to the assessment of industrially available fermentation feedstocks, and to the development of new feedstock products for specific fermentation applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900571
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  • 2
    Electronic Resource
    Electronic Resource
    Structural characterization of vulcanizates. Part V. Determination of degree of chemical crosslinking of natural rubber gum vulcanizate networks (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2215-2226 
    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 general treatment is given of the methods to be used in other parts of this series for calculating the degree of chemical crosslinking in natural rubber vulcanizates from stress-strain measurements in extension and from equilibrium volume swelling measurements. Corrections are required for the presence in the vulcanizate of appreciable quantities of particulate solids or soluble diluents and for the introduction of foreign atoms into the rubber network. For this purpose distinction is made between the rubber vulcanizate, the rubber matrix, the rubber network, and the rubber hydrocarbon component of the network. Expressions are derived, in terms of these concepts, for the Money-Rivlin parameter, C1, measured on vulcanizates which have undergone various treatments.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070111111
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  • 3
    Electronic Resource
    Electronic Resource
    Structural characterization of vulcanizates. Part VIII. The N-cyclohexylbenzothiazole-2-sulfenamide-accelerated sulfur vulcanization of natural rubber at 140-180°C. and of synthetic cis-1,4-polyisoprene at 140°C (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2271-2283 
    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: Vulcanization of natural rubber at 140°C. with a CBS-accelerated sulfur system of conventional type gives rise to a structurally complex network in which the number of sulfur atoms combined per chemical crosslink present increases from 12 to 21 with increasing reaction time. The complexity of the network increases with increasing temperature of vulcanization. Crosslinking of a purified synthetic cis-1,4-polyisoprene proceeds more slowly and yields a slightly more complex network. Despite this overall similarity the natural rubber vulcanizates exhibit considerably higher tensile strengths.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070111114
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  • 4
    Electronic Resource
    Electronic Resource
    Structural characterization of vulcanizates. Part VII. The N-cyclohexylbenzothiazole-2-sulfenamide-accelerated natural rubber-sulfur system (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2255-2269 
    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 crosslinking efficiency of sulfur in the vulcanization system comprising (in parts by weight) natural rubber (100), sulfur (1.5), N-cyclohexylbenzothiazole-2-sulfenamide (2.37), zinc oxide (5), and lauric acid (1-10) is relatively insensitive to the lauric acid concentration and to the temperature of vulcanization (between 100 and 140°C.). The networks formed contain initially 8-11 combined sulfur atoms per chemical crosslink present, but this number falls progressively to about 4 as the reaction proceeds. The results are consistent with the intermediate formation of a rubber-soluble complex of cyclohexylamine with zinc benzothiazolyl mercaptide. This complex is believed to be responsible also for the further slow crosslinking which the vulcanizates undergo on standing at room temperature.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070111113
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  • 5
    Electronic Resource
    Electronic Resource
    Structural characterization of vulcanizates. Part VI. The 2-mercaptobenzothiazole-accelerated natural rubber-sulfur system (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2227-2253 
    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 crosslinking efficiency of sulfur in the vulcanization of natural rubber in the presence of 2-mercaptobenzothiazole, zinc oxide, and lauric acid has been determined as a function of cure time, cure temperature, and lauric acid concentration. With a low concentration of lauric acid structurally complex networks are formed, which contain 11-19 combined sulfur atoms per chemical crosslink present. The complexity increases with time of vulcanization. With a high lauric acid concentration much simpler networks are formed, which become progressively more simple as reaction proceeds (6 network-combined sulfur atoms per chemical crosslink, decreasing to 2.4 with time). Increasing the cure temperature from 100 to 140°C. reduces the efficiency of crosslinking in both cases. The changes in efficiency are attributed to the influences of the reaction variables (in particular, the concentration of rubber-soluble complexes of the zinc laurate with zinc benzothiazolyl mercaptide) on the structure and subsequent reactions of initially formed polysulfidic crosslinks.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070111112
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  • 6
    Electronic Resource
    Electronic Resource
    Hydrodynamic properties of polyelectrolytes. Part IV. Viscosity of polyelectrolytes (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 21 (1956), S. 495-503 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The different types of viscosity behavior which have been observed for polyelectrolytes are discussed and classified. Data are presented for sodium deoxyribonucleate and for sodium polyacrylate of different molecular sizes, and give information on the influence on the viscosity of the degree of polymerization and the flexibility of the molecule. The influence of the shear gradient is also considered. A qualitative interpretation is given based on the size of the polyions and their mutual interactions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120219913
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrodynamic properties of polyelectrolytes. Part II. Poly-4-vinylpyridine (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 21 (1956), S. 473-482 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrodynamic properties of fractionated samples of poly-4-vinylpyridine have been studied. The intrinsic viscosities and the Huggins' constant (k′) have been obtained. The effect of shear on the viscosity disappears at high dilution. The sedimentation constants (S0) have been measured, and the streaming birefringence has been investigated at various concentrations and shear gradients. The Peterlin theory for concentrated solutions is in good agreement with the results for the orientation angle, but is not so well in accord with the magnitude of the birefringence. The partial specific volume is low (0.685). Molecular weights have been calculated for the fractions, and it is concluded that the shape of the molecules in solution approximates to that of a stiff coil.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120219911
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  • 8
    Electronic Resource
    Electronic Resource
    Hydrodynamic properties of polyelectrolytes. Part I. Poly-4-vinyl-N-n-butylpyridinium bromide (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 21 (1956), S. 463-472 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity, streaming birefringence, and sedimentation of a sample of poly-4-vinyl-N-n-butylpyridinium bromide have been measured in aqueous and in sodium chloride solutions. The theory of Peterlin for concentrated solutions has been found to be in agreement with the results. Values of the molecular weight have been calculated by different methods and a value of 9 × 105 has been chosen.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120219910
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  • 9
    Electronic Resource
    Electronic Resource
    Hydrodynamic properties of polyelectrolytes. Part III. Sodium alginate (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 21 (1956), S. 483-493 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity and streaming birefringence of fractionated and unfractionated samples of sodium alginate have been measured at various concentrations, and rates of shear, and in the presence and absence of added salt. The viscosity data show the concave upward curve typical of polyelectrolytes at low concentrations, but pass through a minimum at higher concentrations. The influence of shear is least at this minimum. The initial slope of the orientation angle versus velocity gradient curves increases with concentration, but Δn/c is independent of concentration. The semiempirical theory of Peterlin for concentrated solutions is obeyed by the data for Δn, but not by that for the orientation angle. Molecular weights have been calculated from the hydrodynamic parameters. The viscosity behavior is interpreted in terms of the rigidity of the molecule.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120219912
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  • 10
    Electronic Resource
    Electronic Resource
    The nitrosation of nylon (1958)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 33 (1958), S. 447-455 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nitrosation of nylon 66, with the use of four different nitrosating agents, has been investigated. By the more vigorous nitrosating reactions, heterogeneous nitrosation of nylon yarn occurs rapidly and proceeds to completion in a few hours. In this reaction the amide hydrogen is substituted by a nitroso group to give the structure By heating the nitrosated polyamides, nitrogen is evolved, and polyesters are formed. The kinetics of this change have been fully investigated. Caustic alkali reacts rapidly with nitrosated nylon. Free radicals are produced on exposure of the nitrosated nylon to visible radiation. Partial nitrosation of nylon yarns has been carried out with the use of a running threadline system; the physical properties of the resulting yarns have been examined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1958.1203312641
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