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  • Articles  (12,080)
  • Wiley-Blackwell  (12,080)
  • Nature Publishing Group (NPG)
  • Springer Science + Business Media
  • 1980-1984  (12,080)
  • Physics  (9,331)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (5,610)
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  • Articles  (12,080)
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  • 1
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly[2-(methylsulfinyl)ethyl acrylate] (1) was synthesized as well as derivatives 14C-labelled in side groups (6) or 14C-labelled in the main chain (11). Polymer 11 with the 14C-labelled main chain was fractionated by precipitation. The η-M-relation determined by measurements of unlabelled polymers in the ultracentrifuge for comparison was used to establish the viscosimetrically determined molecular weights of the labelled fractions. After intravenous application of aqueous solutions of the polymer in rats the excretion rate up to 72 h after treatment was ascertained to ca. 50%; the concentration in the blood serum was found to be strikingly high. A tendency to reinforced storage in organs of high phagocytose activity by growing molecular weight was observed. The tumor affinity was  -  if at all  -  low.
    Additional Material: 6 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 277-288 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The low-frequency viscoelastic behaviour of three stereoregular samples of poly(ethyl methacrylate) (PEMA) in the main transition region was investigated. The main effect of tacticity in the transition from the syndiotactic sample to the isotactic one consists in a shift of the main transition region (or of the glass transition temperatures, Tg) to lower temperatures by ≈ 70 K. The temperature dependence of the shift factor of all samples could not be adequately described by the single Williams-Landel-Ferry (WLF) equation within the whole range of temperatures; in the range T〉Tg+60K, isotactic PEMA exhibited the largest departures from the WLF equation. In all cases, departures from the WLF equation could be quantitatively described in terms of the temperature dependence of the Andreade coefficient β. The temperature dependence of the Andreade compliance, JA, was also most pronounced for the isotactic sample. Vertical correction of the complex modulus G*, with WLF horizontal shifts preserved, led to the lowest activation energy ΔH for the isotactic sample, which means the highest magnitude of secondary relaxation mechanism in this sample. The birefringence measurement showed that the molecular nature of the deformational birefringence is independent of the tacticity of the sample and does not vary in the range Tg+25K〈T〈Tg+100K. In all the characteristics mentioned here, parameters of a conventional sample obtained by radical polymerization approached those of the syndiotactic sample.
    Additional Material: 9 Ill.
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  • 3
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of some series of oligo(oxytetramethylene oxyterephthaloyl) [oligo(butylene terephthalate)s] with different but well-defined end groups is described. The separation of artificial mixtures of the oligomers by high pressure liquid chromatography was studied under various elution and column conditions, and thus, the purity of the individual oligomers was demonstrated. The equilibrium melting point Tm0 = 236 ± 4°C and the corresponding heat of melting ΔHm0 = 28,7 kJ·mol-1 of poly(butylene terephthalate) was determined from the analysis of the melting behaviour of the oligomers as depending on the degree of polymerization and the structure of the end groups.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 333-340 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several potentially thermostable polyamides were prepared. 2,2′-Diiodobiphenyl-4,4′-dicarboxylic acid and its diacid chloride 1 were synthesized. The latter was condensed with several amines, e.g., aniline, p-toluidine, p-chloroaniline, and 2-aminopyridine, to prepare model compounds of polyamides testing the reactivity of the diacid dichloride 1 towards various amines, and to compare their spectra with those of the polymers. The polyamides themselves were prepared by solution and melt condensation of diacid chloride 1 with the following diamines: p-phenylenediamine, m-phenylenediamine, 2,6-diaminotoluene, benzidine, bis(4-aminophenyl)-methane, 4,4′-diaminobiphenyl sulfone, and 3,3′-diaminobenzophenone. The solubility of the polyamides in different solvents and their inherent viscosities were also measured. The values of the inherent viscosity were in the range of 0,1-1,9. The UV, IR, and 1H NMR spectra of the prepared polyamides were recorded. The melting points of the polymers were found to be higher than 360°C and the thermogravimetric curves showed that the polymers are stable up to 400°C in air.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 373-382 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of pure ethylene polymerizations performed to maximum pressures of 2,5 kbar and temperatures up to 250°C is discussed. The rate data which are obtained via quantitative infrared and near infrared spectroscopy closely fit to an overall polymerization rate law of the order 2,5 ± 0,2 in the ethylene concentration. The overall activation energy is determined to be 136,3 ± 6 kJ/mol. For the initiation reaction an activation energy of 209,8 ± 12 kJ/mol is derived. This fairly large value establishes that in dense high purity ethylene a thermally initiated (spontaneous) reaction to high molecular weight material occurs.
    Additional Material: 6 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 383-397 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: NMR chemical shifts of the methoxyl and α-methyl protons in the alternating methyl methacrylate-styrene copolymer are calculated by taking into account the contributions of the diamagnetic shielding and the magnetic anisotropy effect of the benzene rings in styrene units. The conformational probabilities of the copolymer chain are calculated according to Flory's matrix method. It is deduced from the calculation that NMR should occur at higher field for the methoxyl and at lower field for the α-methyl protons of the methyl methacrylate unit in meso configuration with an adjacent styrene unit (regarding the methoxycarbonyl and phenyl groups) than for the corresponding protons in the unit of racemic configuration. Further, the differences between the chemical shifts for these protons in meso and racemic dyads are nearly equivalent to the differences in chemical shifts between two adjacent peaks of the observed triplet spectra. This result indicates that the spectral assignment based on a theoretical calculation is quite consistent with the one made by a conventional simulation method: from the lower magnetic field, peaks of cosyndiotactic, coheterotactic, and coisotactic triads appear in this order for the methoxyl protons and in the opposite order for the α-methyl protons. Magnetic anisotropy effect contributes to these tacticity-dependent chemical shifts to a far greater extent than diamagnetic shielding. The variation of the chemical shifts due to measuring temperature, probability of isotactic addition, and interactions between groups more than five bonds apart is also discussed.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 823-838 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity of aqueous polyacrylamide solutions does not remain constant. During a period of many weeks it decreases by as much as 30%. Simultaneously a loss of flocculation activity occurs. This unusual behaviour  -  also called ageing or solution instability  -  is examined. Viscosity and light scattering investigations were made. The viscosity was also determined by addition of substances which influence hydrogen bonds. It could be demonstrated, that in high molecular weight polyacrylamide hydrogen bonds are effective. Light scattering measurements result in curved angular dependence of scattered light, which must be regarded as real and specific for the high molecular weight polyacrylamides in water. The Zimm plot for polyacrylamide in ethylene glycol was undistorted. The refractive index increment decreases with time during the investigations. From the Zimm plots it follows, that the radius of gyration decreases with time. The molecular weight however remains constant. Based on the experimental results a mechanism is assumed with a long-term conformational change of the macromolecules. The orientated segments  -  stabilized by hydrogen bonds  -  are slowly destroyed by occupation of “active sites” by water molecules. Chain degradation as well as disentanglement could be excluded. A molecular interpretation is given.
    Additional Material: 13 Ill.
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Among the methods to introduce functional groups in macromolecular compounds, the initiation of free radical polymerization by functional peroxyesters was investigated. m- and p-tert-butyldioxycarbonylbenzoic acids (3 and 8) were synthetized and their properties were studied. Differential scanning enthalpimetric study of the thermolysis kinetics of 3 and 8 led to the conclusion that these compounds are a little more stable than O,O-tert-butyl hydrogen monoperoxyphthalate (1). Thus, they could be applied under similar conditions. Solution and bulk polymerizations of styrene initiated by 3 or 8 were found to be efficient methods to obtain polystyrene substituted by carboxylic functions.
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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
    Notes: Modified polystyrenes were obtained by free radical polymerization of styrene using the macroinitiators α-tert-butyldioxyterephthaloyl(or phthaloyl)-ωtert-butyldioxyterephthaloyl(or phthaloyl)poly(oxyethylene) (3 and 4), which were synthetized. To examine the stability of such compounds, thermolysis kinetics of model compounds, OO-tert-butyl O-methyl monoperoxyphthalate (6) and terephthalate (7) were studied by differential scanning enthalpimetry. Suspension polymerization of styrene applying the industrial method, showed that the macroinitiator is able to initiate the process. A polystyrene containing up to 4% by weight oxyethylene units was obtained.
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  • 10
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1H NMR spectra of alternating copolymers of methyl acrylate with styrene, methyl acrylate with α-methylstyrene, and methyl methacrylate with α-methylstyrene show triplet splittings at the methoxyl protons regions, which apparently reflect the cotacticity of triad sequences having a (meth)acrylate unit in the center. The two intervals between two neighboring peaks of the triplet are nearly equivalent for each alternating copolymer, whereas the absolute value of the splitting width is significantly different from one alternating copolymer to another. A theoretical interpretation is given for this observation by calculating the chemical shifts of the methoxyl protons in combination with a conformational analysis of the copolymers. The chemical shift of the protons in meso or racemic type dyad sequence is assigned by averaging the shieldings over all the preferred conformations for the dyad and is accumulated to give the shifts in triad sequences: iso = meso + meso, hetero = meso + racemic, syndio = racemic + racemic. The cotacticity-dependent splittings thus calculated are quantitatively in accordance with the observed spectra and discussed in terms of conformational variation of the copolymers depending on the presence of α-methyl group(s) in neither, either, or both of the monomeric unit(s).
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