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• 1
Electronic Resource
Springer
Rheologica acta 1 (1958), S. 213-215
ISSN: 1435-1528
Source: Springer Online Journal Archives 1860-2000
Topics: Chemistry and Pharmacology , Physics
Description / Table of Contents: Zusammenfassung Für beide Fälle, spröden Bruch und stufenweiser Bruch, wurde nur sehr geringe Deformation oder Verlängerung beobachtet und Grenzbedingungen hinsichtlich Dehnungsgeschwindigkeit und Temperatur reproduzierbar erhalten. Die Bruchgrenzen geben die Bedingungen, bei denen der viskose Widerstand entsprechend den lokalen Spannungskonzentrationen, d. h. entsprechend den „grip“-Effekt die Kohäsion des Materials übersteigt, und die Entwickelung der Trennfläche wird verfolgt. Bei der Grenzbelastung für das Absinken der Spannung mag die Viskosität der Flüssigkeiten zu gering sein, um dem Schrumpfen durch Oberflächenspannung im Vergleich mit der Dehnungsgeschwindigkeit entgegen zu wirken. Obgleich die Theorie der Spinnbarkeit, hier vorgeschlagen, nur einen Versuch darstellt, kann behauptet werden, daß die Oberflächenspannung beim Spinnen viskoser Flüssigkeiten mit kleineren Molekülen eine wichtige Rolle spielt. Für höhermolekulare Substanzen wird neben der Viskosität auch die Gummielastizität ausschlaggebend.
Notes: Conclusion In both cases, brittle fracture and dropping breakdown, only very little deformation or elongation was observed in the experiments mentioned above, and limiting conditions were obtained reproducibly with respect to rate of extension and temperature. The brittle limits give the condition where the viscous resistance due to locally concentrated stress, i. e. the grip effect (5) exceeds cohesion of the materials, and development of the surface of separation is followed. At the dropping limits, the viscosities of the liquids may be too small to resist shrinking by surface tension with respect to the rate of extension. Although the theory of spinnability proposed here may be only tentative, it can be pointed out that surface tension plays some important role in spinning of viscous liquids of lower molecules. Concerning higher molecules, rubber-like elasticity as well as viscosity may become more important (6).
Type of Medium: Electronic Resource
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• 2
Electronic Resource
Hoboken, NJ : Wiley-Blackwell
Journal of Polymer Science 59 (1962), S. 321-328
ISSN: 0022-3832
Keywords: Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Physics
Notes: Spiral structures on lamellar single crystals of polyethylene have been ascribed to screw dislocation. Several photographs are shown which seems to verify the possibility of origination of the screw dislocations due to the collision of two growing single crystals. This mechanism accounts for the following facts often found in these spiral structures. (1) Spiral structures often grow from the intersection of two single crystals. (2) The distances from the center of spirals to the nearest edges of the two crystals are approximately equal to each other. (3) Centers of the spirals are often located on the diagonal of the bottom single crystal on which they grew. (4) Daughter crystals formed on a contour line farther from the center of the mother crystal are smaller.
Type of Medium: Electronic Resource
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• 3
Electronic Resource
Hoboken, NJ : Wiley-Blackwell
Journal of Polymer Science 37 (1959), S. 51-70
ISSN: 0022-3832
Keywords: Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Physics
Notes: The theory of bulk viscosity as developed for the liquid state was applied to amorphous high polymeric systems. The isothermal volume contraction, the dependence of shear viscosity, and the fictive temperature of quenched high polymeric substances are all related to the bulk viscosity and explained by this theory. Simple representations are given for compressibility, bulk modulus, shear modulus, thermal expansion coefficient, and heat capacity, all of which are necessary to discuss the bulk viscosity. The theory has been compared with the experimental results for natural rubber, polystyrene, polyisobutylene, and polyester.
Type of Medium: Electronic Resource
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• 4
Electronic Resource
Hoboken, NJ : Wiley-Blackwell
Journal of Polymer Science 61 (1962), S. S1
ISSN: 0022-3832
Keywords: Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Physics
Type of Medium: Electronic Resource
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• 5
Electronic Resource
New York : Wiley-Blackwell
Journal of Polymer Science Part A-2: Polymer Physics 4 (1966), S. 161-171
ISSN: 0449-2978
Keywords: Physics ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Physics
Notes: It has been shown that lamellar crystals of amylose V complexes with 71 helical configuration can be obtained by using complexing agents larger in cross section than n-butanol. The electron diffraction studies indicated a new unit cell for the unheated lamellar crystals which are composed of molecules with 71 helical configuration and hold water molecules on the exterior of the helix. Furthermore, from a throughly dried specimen at 100°C. in vacuo we obtained a pattern which showed only three Debye rings. Its spacings were explained by a two-dimensional hexagonal unit cell having a = b = 14.7 A. proposed by Zaslow. It was also found that when the crystals were dispersed in methanol at room temperature, their electron diffraction pattern was the same as that of the anhydrous amylose V complex of n-butanol.
Type of Medium: Electronic Resource
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• 6
Electronic Resource
Hoboken, NJ : Wiley-Blackwell
Journal of Polymer Science 39 (1959), S. 435-443
ISSN: 0022-3832
Keywords: Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Physics
Notes: The enormous increases of the viscosity, η, and the associated activation heat, Qη, in concentrated polymer solutions are attributed to the formation of intermolecular linkages between high polymer molecules and to the increase of glass transition temperature with increasing concentration of the solution. In this paper, the effects of the intermolecular linkages on the viscosity of moderately concentrated solutions were discussed. In this concentration range, η and Qη are represented by unique functions of reduced concentration, vR = BMv2, and the following equation was derived for Qη; \documentclass{article}\pagestyle{empty}\begin{document}$Q_\eta - Q_{\eta 0} = 2\Delta Ev_R /\left( {1 + v_R ^2 } \right)1/2$\end{document} Here M is the molecular weight of the polymer, v2 is the volume fraction of the polymer, ΔE is the energy to form an intermolecular linkage, B is a constant for the solution, and Qη0 is the activation heat of viscosity for the solvent. The dependency of η on vR shifts from a first power proportionality to a third power at vR = 1/2. The theory was compared with experiments for solutions of cellulose tributyrate in trichloropropane, polyvinyl alcohol in water, polyvinyl acetate in acetone, and polyisobutylene in xylene.
Type of Medium: Electronic Resource
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• 7
Electronic Resource
Hoboken, NJ : Wiley-Blackwell
Journal of Polymer Science 40 (1959), S. 255-262
ISSN: 0022-3832
Keywords: Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Physics
Notes: The enormous increases in the viscosity, η, and the associated activation heat, Qη, in concentrated polymer solutions are attributed to two different factors. One is the formation of intermolecular linkages between high polymer molecules, and the other is the increase of glass transition temperature, Tg, with increasing concentration of the solution. In this paper, the effect of the increase of Tg in solutions of extremely high concentration is discussed. The apparent activation heat of viscosity, Qη, in this concentration range is represented by the equation, Qη = 2ΔE + Qη0. The first term is the increase of Qη due to the intermolecular linkages, and ΔE is the energy to form a linkage. The second term is the activation energy for the vitrified solution where intermolecular linkages do not exist, and it is represented by the equations, (Qηs/Qη2)1/2 = 1 - Aw2 and A = 1 - (Qηs/Qη0)1/2, where A is a constant for the solution and Qη2 and Qηs are the activation heats of viscosity for the polymer and the solution, respectively. The value of A remains constant up to 100% for polystyrene in dibenzyl ether, polymethyl methacrylate in diethyl phthalate, and polyvinyl chloride in tricresyl phosphate. The constant A is always very close to unity for polymeric solutions. The general tendency of concentration dependence of Qη in the whole range of concentration is discussed.
Type of Medium: Electronic Resource
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• 8
Electronic Resource
Hoboken, NJ : Wiley-Blackwell
Journal of Polymer Science 42 (1960), S. 213-222
ISSN: 0022-3832
Keywords: Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Physics
Notes: The rate of spherulite growth has been measured for various polymers. Several authors have developed the theory for the rate with emphasis on its temperature dependence but without reference to its absolute value. In this paper, a theory of the absolute rate of growth is put forward on the basis of the perfect crystal growth mechanism of Volmer-Frenkel and the absolute reaction rate theory of Eyring. The linear rate of growth, G is given by \documentclass{article}\pagestyle{empty}\begin{document}$G=(4kT/d_1 d_3 \eta L)[1 - \exp \{ - \frac{{H_m T}}{{RT_m ^\circ T}}\}]\exp \{ - 1/18\frac{{H_m T_m ^\circ}}{{RTT}}\}$\end{document} For typical polymers, this equation is approximated by \documentclass{article}\pagestyle{empty}\begin{document}$G=(4kT/d_1 d_3 \eta L)\exp \{ - 1/18\frac{{H_m T_m ^\circ}}{{RTT}}\}$\end{document} where d1 is the diameter of the polymer molecular, d3 the length of the segment, ηL the local viscosity near the crystal surface, ΔHm the heat of fusion for a mole of segments, Tm° the equilibrium melting temperatures, and ΔT = Tm° - T. The glass temperature for the local viscosity is assumed to be lower by δTg than that for usual viscosity, and the equilibrium melting temperature Tm° is assumed to be 5° higher than the apparent melting point Tm. The values of G calculated by this theory show good agreement with observed values for polyethylene succinate and nylon 6.