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  • 1975-1979  (6)
  • Polymer and Materials Science  (6)
  • Development
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Material
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  • 1
    Electronic Resource
    Electronic Resource
    Amine-cured epoxy resins: Adhesion loss due to reaction with air (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 1095-1102 
    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 variability in adhesive bond strength and extent of cure of room-temperature, amine-cured epoxy resins has limited their applications. This paper reports the observation of microscopic crystal formation at the interface of the resin with air, resulting in a variably lower resin curing rate, extent of cure, and up to ten times lower adhesive bond strength. These crystals were identified as an amine bicarbonate salt, resulting from the reaction of the amine at the surface of the curing mixture with air. The bicarbonate formation seems to be general for the types of hardeners used in room-temperature curing. The amine-bicarbonate compound can be decomposed back to the amine by heating above 80°C. Otherwise, exposure of room-temperature systems to air before bonding is undesirable.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210423
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Characterization of selectively degraded poly(ethylene terephthalate) (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 765-774 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To investigate the morphology of unoriented poly(ethylene terephthalate) (PET) films and the selective character of the aminolysis of PET, 67% crystalline polymer samples were degraded with 40% aqueous methylamine at room temperature. The aminolyzed PET samples were subjected to gel permeation chromatography (GPC), viscometry, electron microscopy, and small-angle x-ray diffraction (SAXD). Weight loss and density crystallinity measurements were also made.After 24 hr of aminolysis, the amorphous regions and chain folds were completely removed. The long molecular chains in the semi-crystalline polymer were reduced to monodisperse rods having a molecular weight of 1,800. The corresponding lamellar thickness was calculated to be 101 Å, consistent with the x-ray diffraction and electron microscope (EM) measurements. The EM photographs of “stripped” crystals show the lamellar structure previously found for other selectively degraded polymeric materials. The weight of crystalline debris remaining was consistent with the initial crystallinity. After degradation the crystallinity as determined by density was 96%.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.180130409
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of drawing on the unit cell dimensions of crystallites in commercial PET fibers (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 373-376 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140216
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Selective chemical etching of poly(ethylene terephthalate) using primary amines (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 1935-1946 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several primary amines have been examined as selective degradative etchants for the investigation of poly(ethylene terephthalate) (PET) morphology. The objective is to remove less ordered regions, leaving crystals intact. The amines include 40% and 20% aqueous methylamine, 70%-40% aqueous ethylamine and pure and 40% aqueous n-propylamine. Weight-loss and x-ray diffraction data show that certain concentration of aqueous amine solution simultaneously degrade and crystallize PET. This observation indicates the hazard of using some of these amine reagents to characterize PET morphology since the crystalline structure found after etching is likely to be a result of solvent-induced crystallization during degradation. Data for 40% aqueous methylamine used at room temperature shows that crystallization does not occur during etching, and in light of earlier research indicates the favorable nature of this reagent as a selective degradative medium for PET. Application of this reagent disclosed that in oriented PET fibers chemical stress cracking occurs, causing the degradative reagent to lose its selectivity.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.180161104
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Chemical degradative stress cracking of poly(ethylene terephthalate) fibers (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 16 (1978), S. 2057-2077 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(ethylene terephthalate) (PET), after certain thermal and mechanical histories, exhibits stress cracking when exposed to 40% aqueous methylamine. This reagent has also been used for selective degradation of PET films. Stress cracking is shown to occur during degradation only when a specimen supports an internal or externally applied stress, above a critical level. The cracking density in a filament is shown by the present work to increase as the draw ratio is increased or when the fiber is highly annealed. This increased cracking is associated with an increase in the magnitude of the internal residual stress resulting from molecular orientation developed during these processes. Because of this, crack density and fiber birefringence were found to correlate well. In addition, the geometry of the stress-cracking pattern along a filament is affected by internal residual stress since the propagation of spiral and helical cracks results from the effect of a biaxial stress field remaining at the filament surface after processing.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.180161114
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal shrinkage of oriented semicrystalline poly(ethylene terephthalate) (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 575-590 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The shrinkage of commercial oriented poly(ethylene terephthalate) filaments was studied within the framework of the kinetic theory of rubberlike elasticity. Previous workers had found that the shrinkage and optical behavior of amorphous polymers could be satisfactorily explained in terms of this theory. Such an analysis is now applied to semicrystalline samples of moderate and high draw ratios (from 2× to 6×).It was found in this work that the thermal shrinkage force behavior as well as the optical anisotropy as a function of stretch can be explained in terms of the theory of rubberlike elasticity, if the following reasonable assumption is made: the average number of statistical segments per network chain in the noncrosslinked sample increases as a function of the draw ratio. A possible mechanism for such behavior is the relaxation of some of the chain entaglements due to the strain imposed externally on the fiber.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140401
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    Paper (German National Licenses)
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