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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 27 (1994), S. 6740-6745 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 112-116 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A technique has been developed to measure the linear mass density of fibers and ribbons, and adapted to the study of stress/strain coupled diffusion in polymeric materials. The technique overcomes the limitations of sensitivity and range, typical of traditional diffusion measurement techniques, and can be used for a wide range of fiber densities. It is also possible to monitor stress or strain within the fiber while measuring the change in mass, without requiring the fiber to be at equilibrium or interrupting the experiment. Estimates of material property changes, as exemplified by tensile modulus changes, can also be made during the course of the experiment. The mass per unit length, at any given time, of polymer fibers or ribbons under known stresses and strains can be determined by this technique. From this it is possible to estimate the gain or loss in weight in the sample due to permeants diffusion. Some preliminary result of constant strain and constant stress experiments on ribbons of polycarbonate, polyimide, and precured epoxy, and KevlarR monofilaments, are discussed and the scope and resolution of the apparatus are indicated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 20 (1985), S. 1645-1659 
    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 A model for the compressive buckling of an extended polymer chain is presented. The application of classical elastic instability analysis to an idealized polymer chain reveals that the bending rigidity and critical buckling loads for a chain are proportional to the force constants for valence bond angle bending and torsion. Highly oriented polymer fibres are treated as a collection of elastic chains that interact laterally. The critical stresses to buckle this collection of chains are calculated following a procedure developed to predict the compressive strengths of fibre-reinforced composites. This buckling stress is predicted to be equal to the shear modulus of the fibres and is the limiting value of compressive strength. Comparison of experimental and predicted values shows that the theory overestimates the compressive strength, but that there is a correlation of shear modulus with axial compressive strength. Consideration of flaws in both the theory and the material indicate that the compressive strength should be proportional to either the shear modulus or shear strength of the fibres.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 45 (2000), S. 405-410 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polyhydroxyamic acid (PHAA) with an inherent viscosity of 0.45 dL/g was prepared from 3, 3'-dihydroxybenzidine and pyromellitic dianhydride. The mechanical and thermal properties of PHAA films and powders before and after annealing were investigated on the basis of their potential use as fire-safe polymers. Cyclization of PHAA to the corresponding hydroxy-containing polyimide is an endothermic reaction. During annealing of PHAA, water was released at 180 °C and carbon dioxide at over 400 °C. The weight residue of PHAA at 900 °C was about 38 %. After annealing at 500 °C, this value increased to 75 %. After annealing at 450 °C, the ultimate stress and initial modulus of the PHAA precursor films increased from 133.8 MPa and 5.86 GPa to 306.2 MPa and 11.0 GPa, respectively.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 22 (1987), S. 419-428 
    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 A modified scarf joint specimen was developed for characterizing the adhesive behaviour of poly (p-phenylene benzobisthiazole) (PBT) film/epoxy composites. This method subjected samples to varying amounts of normal stress (tensile or compressive) and shear stress. This resulted in the determination of two adhesive strengths; one in the absence of shear stress and one in the absence of normal stress. As a result, the dependence of the adhesive strength on the degree of normal stress was determined. The adhesive behaviour of PBT/epoxy composites was investigated at cure temperatures of 55, 85, 115 and 215°C. Adhesive strengths of 3.5 and 8.2 MPa were measured in the absence of shear and normal stress, respectively, for samples cured at 55° C. A decrease in adhesive strength with increasing cure temperature was attributed to residual cure and thermal stresses. The fracture of these composites was predominantly adhesive, resulting in a clean delamination of the PBT film from the epoxy surface. A modified Tsai-Wu failure criterion is suggested for these composites.
    Type of Medium: Electronic Resource
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  • 8
    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 A previously derived theoretical compressive strength for fibres composed of uniaxially oriented and extended polymer chains was compared with the measured strengths of several high performance fibres. For failure initiated by elastic microbuckling of polymer chains or fibrils, the maximum fibre strength is predicted to be equal to the minimum longitudinal shear modulus of the fibre. An excellent linear correlation between measured strengths and torsion moduli was obtained for four liquid-crystalline polymer fibres and high modulus graphite fibres. The correlation shows that measured strengths are 30% of the corresponding torsion moduli for all these fibres. A high modulus, high strength polyethylene fibre exhibited a compressive strength-torsion modulus ratio that was lower than the value 0.3 obtained for the other fibres examined in this study.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 39 (1989), S. 93-102 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé On présente une technique basée sur la visco-élasticité sous impulsion qui, en combinaison avec l'élasticité linéaire incrémentielle, permet de surveiller les changements mécaniques et rhéologiques qui surviennent lors d'un processus de solidification. On applique en particulier cette technique à la cuisson d'une résine epoxy. Pour un tel système, diverses propriétés peuvent être mesurées en fonction du progrès de la polymérisation: durée et température de gélification, module de traction à l'équilbre, contraintes et bridages associés à la polymérisation, viscosité de l'allongement en conditions stationaires, temps moyen de relaxation, coefficient de dilatation thermique, température de transition à l'état vitreux et propriétés mécaniques en conditions dynamiques.
    Notes: Abstract The technique of Impulse Viscoelasticity, in combination with incremental linear elasticity, is presented for monitoring the mechanical and rheological changes which occur during the solidification process. The technique is specifically applied to the curing of an epoxy resin. For such a system, the properties which can be measured as a function of the cure history are gelation time and temperature, equilibrium tensile modulus, cure stress and shrinkage, steady state elongational viscosity, mean relaxation time, thermal expansion coefficient, glass transition temperature and dynamic mechanical properties.
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  • 10
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 3 (1982), S. 57-58 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new method of applying small (〈3 percent) and uniform compressive strains to organic fibers by shrinkage of a surrounding polymer matrix is reported. The results of this matrix-induced compression on the morphology and tensile properties of Kevlar fiber are examined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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