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  • Chemistry  (33)
  • Inorganic Chemistry  (3)
  • birefringence  (2)
  • Computer Systems
  • 1985-1989  (28)
  • 1975-1979  (5)
  • 1925-1929  (2)
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Keywords
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Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Mechanical properties of oriented fibres of semicrystalline polymers based upon orientation function from optical properties (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 128-130 
    Details
    ISSN: 1435-1536
    Keywords: Orientation of polymer chains ; mechanical properties ; birefringence ; deformation scheme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The computation of the orientational averages is a great problem in the case of semicrystalline polymers. In a previous communication [1] it has been shown that sinθ=f(λ) sinθ′ describes the orientational changes satisfactorily for a certain class of polymers. In this paper some alternative deformation schemes are also discussed. It has been concluded that birefringence provides a useful guideline in the choice of a deformation scheme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414838
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  • 2
    Electronic Resource
    Electronic Resource
    Unified study of the different physical properties of amorphous polymers (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 501-508 
    Details
    ISSN: 1435-1536
    Keywords: Amorphous polymers ; mechanical properties ; birefringence ; thermal condcutivity ; thermal expansivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Uptil now it has not been possible to explain the different physical properties of amorphous polymers using a model based on a single conceptual scheme. In this paper, a phenomenological model is proposed which tries to explain the mechanical, optical and thermal properties (both thermal conductivity and expansivity) of amorphous polymers. The model has similarities with the composite model, proposed by the present authors, which has proved to be successful in interpreting the different physical properties of semicrystalline polymers. The present model considers the bulk form of the polymer as an aggregate of microscopic units possessing intrinsic physical properties. On drawing, the development of anisotropy in different physical properties is supposed to be due to the development of preferred orientation of these units. The development of the preferred orientation has been estimated directly from birefringence data. The agreement between the calculated and experimental values of the elastic modulus, thermal conductivity and thermal expansivity of PVC, PMMA and PS is found to be reasonable good.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420760
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and some properties of carbazole modified polyvinylchloride and the cation exchange resin therefrom (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 170 (1989), S. 115-125 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Substitution von Chlor in PVC durch 3,6-Diamino-N-methyl-carbazol entsteht ein Kondensat, das in allen Lösungsmitteln für PVC unlöslich ist. Dieses Kondensat ist thermisch stabiler als PVC. Auch die dielektrischen Eigenschaften unterscheiden sich deutlich von denen von PVC. Die Sulfonierung des PVC-Carbazol-Kondensats liefert ein Kationenaustauscherharz mit SO3H- und COOH-Gruppen.
    Notes: The chlorine displacement reaction between PVC and N-methylcarbazole-3,6-diamine affords a condensate which is insoluble in all possible solvents of PVC. The overall thermal stability of this condensate is appreciably higher than that of PVC. The dielectric behavior is also significantly different from that of unmodified PVC. Sulfonation of the PVC-carbazole condensate affords a cation-exchange resin with —SO3H and —COOH functional moieties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051700108
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  • 4
    Electronic Resource
    Electronic Resource
    Unified study of the mechanical and optical properties of polyoxymethylene applying the composite model for the temperature range from -60 to 120°C (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1017-1022 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A unified study of the optical and mechanical properties of polyoxymethylene (POM) is attempted in the framework of the composite model for a wide range of temperature (-60 to 120°C) which covers a region well below and above the γ-relaxation temperature. It was found that the existing two phase models for semicrystalline polymers are not adequate for interpreting the mechanical properties of POM over a wide temperature and drawing ratio range. The composite model takes into consideration the effects due to the change in crystallinity and orientation on drawing. The elastic moduli of the composite units are also calculated in terms of those of its constituents. The orientational changes on drawing were directly computed from the birefringence data. It was observed that the general agreement of the calculated and experimental values of the elastic moduli over the entire temperature and drawing ratio range is quite satisfactory.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870430
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  • 5
    Electronic Resource
    Electronic Resource
    Composite model calculation of the mechanical properties of polypropylene (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1023-1034 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theoretical interpretation of the anisotropic elastic properties of polypropylene is given. It was found that none of the existing models provide a unified description of the mechanical and optical properties of ultradrawn polypropylene. The composite model proposed by the authors, which takes into account the change in orientation and crystallinity on drawing, was applied to investigate the elastic moduli data of polypropylene for a wide range of temperature (-40 to 110°C) and over the entire drawing ratio range. The relationship between θ and θ′, the angles made by the C-axis of the composite unit with drawing direction, was found to be adequately described by the relation tan θ = φ(n) tan θ′. It was further observed that φ(n) in the above relation obtained from birefringence data predicts the correct orientational changes on drawing for the temperature range -40 to 24°C. This makes the evaluation of mechanical properties possible without introducing any arbitrary parameter. However, it is noticed that a particular analytical form of φ(n) with two parameters is quite successful in interpreting the mechanical properties data over the entire temperature range. The abrupt changes of the parameters at certain temperatures seem to be correlated with the β-relaxation and glass transition temperature.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870431
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  • 6
    Electronic Resource
    Electronic Resource
    A composite model for the thermal conductivity of semicrystalline polymers (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 217-226 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A phenomenological model is proposed which considers the polymer as an aggregate of units. The units are composed of two distinct phases  -  amorphous and crystalline. The thermal conductivity of a unit is calculated in terms of those of its constituents. In the undrawn state these units are distributed randomly, and the isotropic thermal conductivity of the bulk results. The development of strong anisotropy in thermal conductivity is explained in terms of the preferred orientation of these units. The structural features of this model are similar to those employed for the interpretation of the mechanical properties. The change in orientation of the units was deduced from the experimental data of birefringence. Finally, the results obtained from the composite model for several semicrystalline polymers are compared with the experimental data and other existing calculations. The model is found to give a fair overall description of the thermal conductivity in the cases of polypropylene, polyoxymethylene, low and high density polyethylene, and polychlorotrifluoroethylene.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880118
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  • 7
    Electronic Resource
    Electronic Resource
    Application of the composite model for the mechanical properties of high density polyethylene (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1009-1015 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The existing models of high density polyethylene (HDPE) fail to tackle effectively the development of mechanical anisotropy on drawing at different temperatures. This paper is concerned with the theoretical interpretation of the anisotropic elastic properties of HDPE by applying the composite model proposed by the authors. The model takes into account the change in orientation and crystallinity on drawing. As far as the orientational changes on drawing are concerned, it is seen that the pseudo affine deformation law tan θ = φ(n) · tan θ′ with φ(n) = n-3/2 is applicable at -60°C only. It is further found that the two parameter analytical form of φ(n) reproduces the correct orientational changes on drawing for the entire temperature range from -60 to 100°C. The agreement of the calculated values of E0 and E90 over the entire temperature range at all drawing ratios is quite satisfactory.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870429
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  • 8
    Electronic Resource
    Electronic Resource
    Composite model for the thermal expansivity of polymers (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 993-1000 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal expansivity of semicrystalline polymers is interpreted within the framework of the composite model which has already been found useful in describing mechanical and optical properties as well as the thermal conductivity of a large number of polymers. The model assumes the polymers to be an aggregate of units composed of crystalline and amorphous phases. The thermal expansivities of the unit are calculated in terms of those of the constituents. In the undrawn state the units are distributed randomly, and the isotropic thermal expansivity of the bulk results. The development of strong anisotropy in thermal expansivity on drawing is explained in terms of preferred orientation of the units. The orientational changes on drawing have been directly calculated from the birefringence versus draw ratio data. The results of these investigations indicate that the present model is quite successful in interpreting thermal expansivity data for poly(oxymethylene) and poly(propylene) over the entire draw ratio and temperature range.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890503
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  • 9
    Electronic Resource
    Electronic Resource
    Polymerization of vinyl ethers by 3d-transition metal oxides (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1209-1217 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Studies on the relative efficiencies of 3d-transition metal oxides as catalysts for the polymerization of vinyl ethers revealed that V2O5 is the most efficient catalyst. Some kinetic studies with the system isobutyl vinyl ether/V2O5/benzene were carried out at ambient temperature. It was found that the rate is second order in isobutyl vinyl ether (IBVE) concentration (0,25 to 2,0mol.1-1) and the inhibition of the polymerization by pyridine suggests a cationic mechanism. Rp increases by the use of benzaldehyde along with V2O5, whereas water (3.10-3mol.1-1) seems to have no effect on Rp. Over the temperature range of 15 to 60°C, Rp as well as [η] attain a maximum value at about 32°C. [η] is unaffected by varying the amounts of oxides, whereas it increases with increasing IBVE concentration. No stereoregularity in the product polymer was observed by using V2O5 alone or in combination with modifiers such as benzaldehyde or carbon disulfide. The kinetics are interpreted in terms of the Hinshelwood-Langmuire mechanism assuming a single point adsorption.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790509
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  • 10
    Electronic Resource
    Electronic Resource
    Modified affine law for the elastic and optical properties of low density polyethylene (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2649-2656 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A unified study of the anomalous mechanical properties and birefringence of low density polyethylene (LDPE) is attempted within the frame work of the rotating element model. The present paper investigates the validity of the affine transformation rule used in the Ward model and suggests a modified affine law which is based on the consideration that the units are only reoriented and, unlike the affine law, are not deformed due to the uniaxial stretching. The relationship between the angles made by the C-axis of the unit with the drawing direction in the undrawn state (θ) and the drawn state (θ), is deduced as sin θ = f(n) sin θ′. From the birefringence data of different polymers a two parameter relation of the form f (n) = exp [-(n - 1)α/β] is suggested. Using this new orientation function, the agreement of the predicted values of E0 and E90 for LDPE for the entire draw ratio range between temperatures of 60°C to -125°C, is quite satisfactory. An interesting feature is that the abrupt change in the values of the parameters α and β at two different temperatures may be associated with a phase transition of LDPE at an intermediate temperature.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021861225
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