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  • 1
    Publication Date: 1993-02-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 28 (1993), S. 753-759 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The adhesion of oriented, high-modulus polyethylene-structures to epoxy resins is greatly enhanced by pretreatment with oxidizing acids. For KMnO4/H2O/H2SO4 treatment a maximum increase in adhesion, as determined by pull-out tests, of 600% was found. Chromic and chlorosulphonic acid treatment improves the adhesion with 550% and 300% respectively. Moreover, this improvement was obtained without substantially affecting the mechanical properties. The modulus remained the same, whereas tensile strength decreased by less than 10% after this treatment. By monitoring the changes in surface topography (SEM) and surface composition (X-ray photoelectron spectroscopy) the improvement in adhesion could be related to the introduction of functional oxygen-containing groups, i.e. hydroxyl, carbonyl, carboxyl. Furthermore, at the highest level of adhesion obtained the failure mode changed from interface controlled to shear failure within the polyethylene structure.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 5 (1994), S. 615-617 
    ISSN: 1042-7147
    Keywords: Thermotropic ; Relaxations ; Coefficient of linear thermal expansion ; Tensile modulus ; Orientation ; 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
    Notes: A molecular laminate model is used to explain the properties of unoriented and oriented films of poly(p-phenylene-2,5-didodecyloxyterephthalate) cast from solution. In oriented films the two different crystal modifications, A and B, give rise to room temperature tensile moduli of 15 and 30 GPa respectively. The packing (in clusters) of the side chains in modification A, leading to a glass-like transition in the side-chain regions around -40°C, is largely responsible for this difference. Oriented films of modification A and B have coefficients of thermal expansion of +0.3×10-5 and -1× 10-5 K-1 respectively. It is concluded that the properties of this class of polymers can be adjusted in a systematic way.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 2079-2087 
    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 crosslinking of a series of thermotropic LC polyesters, consisting of a poly(p-phenylene terephthalate) backbone and flexible aliphatic side chains, by electron beam irradiation was studied as a function of the side-chain composition, side-chain length, and irradiation temperature. For a comparison of the effect of irradiation the G(S)/G(X) ratio, as determined from sol-gel or GPC measurements, was used. Crosslinking dominates if this value is smaller than 1, which is the case for four out of five polyesters studied. Only the polyester with hexyloxy side chains shows a slight tendency to degradation. Crosslinking is stimulated by longer side chains and the introduction of hetero atoms that are more easily ionizable, like oxygen. The introduction of an unsaturation has the largest effect and boosts the crosslinking process. Raising the irradiation temperature increases the tendency to crosslinking or degradation already present. For most of the polyesters studied, irradiation slightly improves the mechanical properties of cast films. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1759-1767 
    ISSN: 0887-6266
    Keywords: rigid rod polymer ; thermotropic ; aromatic polyester ; fiber ; modulus ; crystal structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fiber spinning and mechanical properties of four rigid polyesters with alkoxy substituents of different length and placement were evaluated. Properties of oriented fibers from the polymer with dodecyloxy substituents on the terephthalate moiety, PTA12HQ, were significantly affected by the crystal modification. At room temperature the following properties (tensile modulus E, tensile strength σb, and strain at break εb) could be obtained: E = 9.5 GPa, σb = 85 MPa and εb = 1.1% for phase Lf (the “frozen in layered mesophase”); E = 10.4 GPa, σb = 59 MPa and εb = 0.6% for modification A; E = 17.3 GPa, σb = 158 MPa and εb = 1.2% for modification B. Because of the higher amount of main chains per cross sectional area the polymer with hexyloxy side chains, PTA6HQ, showed better properties at a comparable degree of molecular orientation: E = 24 GPa, σb = 270 MPa, εb = 1.4%. Fibers obtained from the polyester with dodecyloxy substituents on the hydroquinone moiety, PTAHQ12, were too brittle to handle. The polyester with dodecyloxy substituents on both moieties, PTA12HQ12, was spun from the isotropic melt. Because of the obtained low degree of orientation, properties (E = 1 GPa, σb = 40 MPa, and εb = 6.3%) were governed by interactions between the chains (the main chains are not load-bearing). © 1993 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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