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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 6 (1968), S. 953-960 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of well-characterized polyamic acids from pyromellitic dianhydride and 4,4′-diaminodiphenyl ether of systematically varied molecular weight and known molecular weight distribution were chemically converted to polyimide films under regulated conditions. The films were essentially noncrystalline, of moderate orientation, and soluble in concentrated sulfuric acid. The mechanical properties of the films varied sigmoidally with the solution properties of the precursor. Molecular weights were derived for the onset of mechanical strength and limiting property values are given. The relations between film properties and molecular structural parameters suggest that cyclization probably occurs here with little contribution from crosslinking, degradation, or other side reactions which would appreciably alter molecular weight and molecular weight distribution.
    Additional Material: 3 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 653-662 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aromatic poly(amic acids) derived from pyromellitic dianhydride and 4,4′,-diaminodiphenyl ether were characterized by dilute solution techniques. Number-average molecular weights M̄n of 13 samples ranged from 13,000 to 55,000 (DP 31-131). Weight-average molecular weights M̄w of 21 samples ranged from 9,900 to 266,000. The ratio M̄w/M̄n was between 2.2 and 4.8. Heterogeneous polymerization yielded higher molecular weight polymer than homogeneous polymerization. The molecular weight could be varied systematically by control of stoichiometric imbalance. Use of very pure monomers and solvent gave polymers of relatively high number-average molecular weight (∼50, 000) and the most probable molecular weight distribution M̄w/M̄n = 2. Impure monomers and/or solvent resulted in lower number-average molecular weight (M̄n ≅ 20,000-30,000) and wider distributions (M̄w/M̄n = 3-5). The Mark-Houwink relation obtained was [η] = 1.85 × 10-4M̄w0.80 The exponent is characteristic of moderately extended solvated coils. The unperturbed chain dimensions (r02/M)1/2 were 0.848 A., and the steric factor σ was 1.24 which is close to the limiting value of unity for an equivalent chain with free internal rotations. The sedimentation constant-molecular weight relation was S0 = 2.70 × 10-2M̄w0.39. This exponent is consistent with the Mark-Houwink exponent.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 1435-1438 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 4 (1966), S. 491-500 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Equations previously developed for the light scattering of polar chain polymers subjected to orientation by an electrical field are extended to the case where the elementary dipoles have arbitrary direction with respect to the chain contour. As an illustration of the theory, measurements were made of the light scattering of nitrocellulose solutions as a function of the angle of observation, the field strength, the direction of the field, and the frequency of the field. The principal results obtained were: the molecules are deformed by the electrical field; orientation is due primarily to a permanent electric moment whose component per chain segment is of the order of 4 Debye; and the relaxation times for molecular orientation are of the order of magnitude predicted by the theory of Stockmayer and Baur.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 1995-2004 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solution characterization measurements indicate that cylization of the polyamic acid from 2,4-diaminoisopropylbenzene and pyromellitic dianhydride (PMDA) to the polyimide can be effected with small change in number-average degree of polymerization. An increase in weight-average molecular weight on conversion to polyimide is attributed to branching side reactions. Inherent viscosities of polyimides from 4,4′-diaminodiphenyl ether and PMDA decreased slowly with time in concentrated (97%) sulfuric acid, probably as a result of hydrolytic cleavage. The zero-time viscosity intercepts were related to both the precursor and the estimated polyimide molecular weight. The latter gave ηinh (c = 0.5% solids) = 2.76 × 10-3M̄0.53w for 60,000 〈 Mw 〈 300,000. The exponent is near the lower limit of 0.5 found in theta solvents. The characteristic ratio of the root-mean-square end-to-end distance of a chain to the square root of its molecular weight is 1.1 Å and the steric factor is 1.1; these results suggest that the unperturbed polyimide chain is almost as extended as an equivalent freely rotating chain, a general feature of long-bonded polymers with p-phenylene rings in the chain backbone.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 9 (1986), S. 67-67 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 11 (1988), S. 559-562 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: LAMMS (Laser Microprobe Mass Spectrometry) has been used to observe the presence and location of a herbicide on plant lea, es. Leaves from soybean plants, sprayed with imazaquin, a member of the imidazolinone class of herbicides, at varying application rates, were examined by LAMMS without any special preparation. A rapid analysis for imazaquin was obtained confirming the suitability of LAMMS as an organic microprobe analyser. A comparison with standard chemical ionization and electron impact mass spectra of imazaquin showed evidence for laser-induced fragmentation.
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 57 (1962), S. 41-52 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been made of the light scattering of poly-L-benzyl glutamate solutions subjected to orientation by an electrical field. Measurements were taken of the effect as a function of the field strength, the angle of observation, the direction of the field, and the frequency of the field. The principal results obtained were the following. (a) The helical molecules are not deformed by the electrical field. (b) The molecular orientation is due primarily to a permanent electric moment whose axial component per monomer unit is of the order of 3 Debye. (c) As predicted by the theory of Burgers, the rotatory diffusion constant was found to vary inversely as the cube of the rod length.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Für eine Reihe von Polyäthylenterephthalatharzen wurde das Molekulargewicht durch Streulichtmessungen in Trifluoressigsäurelösung und die Viskositätszahl in Trifluoressigsäurelösung und in einem Gemisch von Tetrachloräthan und Phenol gemessen. Folgende Viskositäts-Molekulargewichts-Beziehungen wurden nachgewiesen: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\left[ \eta \right]{\rm TFA} = 4,33 \cdot 10^{ - 4} {\rm M}_{\rm W}^{0.{\rm 68}} \left( {{\rm TFA} = {\rm Trifluoressigs{\ddot a}ure}} \right);} \\ {\left[ \eta \right]_{{{{\rm TCE}} \mathord{\left/ {\vphantom {{{\rm TCE}} {{\rm phenol}}}} \right. \kern-\nulldelimiterspace} {{\rm phenol}}}} = 2,29 \cdot 10^{ - 4} {\rm M}_{\rm W}^{0.73} \left( {{\rm TCE} = {\rm Tetrachlor{\ddot a}than}} \right)} \\ \end{array} $$\end{document} Die ungestörten Dimensionen (〈r02〉/M)1/2 wurden nach der Methode von KURATA-STOCK-MAYER (0,985 a.u.) und STOCKMAYER-FIXMAN (0,966 a.u.) abgeleitet. Der sterische Faktor (1, 4) gleicht dem für andere Polymere, die p-Phenylgruppen in ihrer Hauptkette enthalten. Die gefundenen Ergebnisse werden mit früheren verglichen, die sich auf Endgruppenbestimmungen und auf Daten gründen, die durch osmotische und kryoskopische Messungen erhalten wurden.
    Notes: A series of polyethylene terephthalate resins were characterized for molecular weight by light scattering measurements in trifluoracetic acid (TFA) solution and for intrinsic viscosity in TFA and in a mixture of tetrachloroethane (TCE)/phenol. The following viscositymolecular weight relations were established: \documentclass{article}\pagestyle{empty}\begin{document}$$\left[ \eta \right]_{{\rm TFA}} = 4.33 \cdot 10^{ - 4} {\rm M}_{\rm W}^{{\rm 0}{\rm .68}},{\rm }\left[ \eta \right]_{{\rm TFA/phenol}} = 2.29 \cdot 10^{ - 4} {\rm M}_{\rm W}^{{\rm 0}{\rm .73}}$$\end{document} The unperturbed dimensions (〈r02〉/M)1/2 were derived by the method of KURATA-STOCK-MAYER (0.985 a. u.) and STOCKMAYER-FIXMAN (0.966 a.u.). The steric factor (1.4) is similar to that of other polymers with p-phenylene groups in their chain backbone. The results are compared to previous findings based on end group, osmometric, and cryoscopic data.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 1983-1996 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyanoacetylene can be polymerized into linear polymers at low temperatures by anionic initiators. The polymers are brown to black amorphous powders, soluble in polar organic solvents. Their molecular weights are of the order of several thousands and the presence of the acidic acetylenic hydrogen does not seem to be an inhibiting factor in polymerization. Some general features of the polymerization and the products obtained are discussed. It is possible to synthesize copolymers with acrylonitrile, which show spectral and solution properties intermediate between those of the two homopolymers. The difference in structure between the materials obtained after pyrolysis of polyacrylonitrile and polycyanoacetylene is discussed.
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