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  • 1
    Electronic Resource
    Electronic Resource
    Transverse moisture sensitivity of aramid/epoxy composites (1983)
    Springer
    Journal of materials science 18 (1983), S. 652-656 
    Details
    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 Transverse tensile properties of Kevlar 49 aramid/Fiberite 934 epoxy composites have been measured as a function of moisture content. Moisture effects are substantial: losses of 14% in stiffness, 35% in strength and 27% in elongation were observed at 25
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00745562
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  • 2
    Electronic Resource
    Electronic Resource
    Some consequences of a fracture criterion for oriented polymers based on electron spin resonance spectroscopy (1983)
    Springer
    International journal of fracture 21 (1983), S. 107-114 
    Details
    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 La spectroscopie électronique à résonnance de spin (ESR), qui est à même d'annoncer des ruptures de liaisons covalentes au cours de la rupture d'un polymère, a fourni une base expérimentale permettant d'élaborer un modèle atomique de la rupture, qui prenne en compte la distribution des contraintes dans la structure interne du matériau. A l'aide d'un modèle de calcul mis au point par De Vries et Lloyd, on a obtenu des estimations des durées à rupture dans le cas de températures, de contraintes et de vitesses de sollicitation différentes. Les durées à rupture prévues sont en accord avec les observations de l'expérience, ce qui indique l'utilité pratique du modèle basé sur l'ESR. En outre, les paramètres d'activation effective qui découlent d'une mise en corrélation du modèle de rupture macroscopique de rupture de Zhurkov avec les prédictions de l'ESR fournissent un éélairage sur la manière dont la distribution des contraintes intervient dans la détermination de la cinétique du processus de rupture.
    Notes: Abstract Electron spin resonance (ESR) spectroscopy, which is able to monitor covalent bond rupture during polymer fracture, has provided an experimental basis on which to construct an atomistic fracture model which takes proper cognizance of the distribution of stress over the material's internal structure. Using a computer model developed by DeVries and Lloyd, estimations of times to fracture were obtained for several different temperatures, stresses, and stress rates. The predicted rupture times agreed satisfactorily with experimental observations, which indicates the practical utility of the ESR-based model. Further, the effective activation parameters which result when the Zhurkov macroscopic fracture model is correlated with the ESR predictions provide an insight as to the role of the internal stress distribution in determining the kinetics of the fracture process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00941867
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  • 3
    Electronic Resource
    Electronic Resource
    Assessment of olefin-based IUD tail strings (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 4 (1993), S. 289-301 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The „tail string“ that extends from a contraceptive intrauterine device (IUD) into the vagina is an illustrative case in materials engineering design. The strings must satisfy certain criteria for strength and other properties in order to fulfill the function of providing a means of insuring that the IUD has not been ejected, and eventually of helping remove the IUD. This must be done without contributing to an additional risk of unwanted medical side effects beyond those that may be inherent in any such device. Oriented monofilament olefins appear to satisfy these criteria, and have been used successfully in several IUD designs. This article describes a study of two such monofilaments taken from new IUDs, showing how the material's processing, structure, and properties lead to effective performance as tail strings. Several types of used IUDs were also studied, to insure that nothing occurred during use that would alter the conclusions drawn from the study of new strings. © 1993 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770040403
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  • 4
    Electronic Resource
    Electronic Resource
    Use of “penalty” finite elements in analysis of polymer melt processing (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 1029-1034 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 finite element method is an approximate numerical analysis approach of great applicability to a wide variety of field problems. This paper describes the formulation of a convenient method for treating fluid-flow problems relevant to analysis of polymer processing operations, and illustrates its use by means of some linear and nonlinear problems in melt extrusion.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760201508
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  • 5
    Electronic Resource
    Electronic Resource
    Penetration mechanics of textile structures: Influence of non-linear viscoelastic relaxation (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 1068-1072 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: A numerical simulation of ballistic impact and penetration on woven textile panels is described which can easily incorporate a wide variety of realistic constitutive and fracture models. The use of this model in assessing Viscoelastic relaxation effects is illustrated, and is further extended to include non-linear Viscoelastic effects. Since a variety of non-linear models is presently available and there is insufficient evidence to indicate the superiority of any single one in this instance, the Eyring non-linear model was chosen arbitrarily to indicate the ease with which these models may be implemented into the numerical treatment. The results obtained using the non-linear model are compared with comparable computer experiments using linear elastic and linear Viscoelastic models.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760181406
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetics of a sterically hindered amine-cured epoxy resin system (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 166-171 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Fourier transform infrared spectroscopy (FT-IR) and torsional braid analysis (TBA) were used to study the reaction of an epoxy resin system cured with a sterically hindered amine. Isothermal torsional braid analysis showed the apparent activation energy to be approximately 42 kJ/mol. The reaction kinetics were also considered from the unreacted freshly mixed condition and a partially reacted “B-staged” condition using infrared spectroscopy, The B-staged condition is unreactive and stable at room temperature due to the quenching of the primary amine reaction by the glassy structure and the steric hindrance of the secondary amine reaction. Apparent activation energies for these two conditions were found to be 49.4 kJ/mol and 49.0 kJ/mol respectively. The storage life at room temperature of the B-staged resin system is predicted to be at least three months based on extrapolation of the experimental kinetic data.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220306
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  • 7
    Electronic Resource
    Electronic Resource
    A thermodynamic prediction of tie chain length distribution in drawn semicrystalline polymers (1985)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 828-833 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 mechanism underlying fracture of many oriented semicrystalline polymers is hypothesized to be a thermally activated, stress-aided rate process in which the tie chains connecting crystalline units suffer thermomechanical dissociation. Some previous numerical models based on this concept have assumed a Gaussian distribution of tie chain contour lengths which are ruptured progressively by successively higher specimen strains, and have used electron spin resonance (ESR) spectroscopy to obtain the numerical parameters of the distribution. The distribution of tie chain lengths in the intererystalline region is calculated theoretically in this paper, based on minimization of free energy. Our results, although in basic agreement with earlier models, suggest a reinterpretation of some of the ESR findings with regard to molecular fracture processes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760251307
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  • 8
    Electronic Resource
    Electronic Resource
    Nonlinear response and thermomechanochemical degradation of a urethane elastomer (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 131-140 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: We have studied the failure of a urethane elastomer due to cyclic compressive loading, using loading frequencies and specimen sizes for which internal heat generation is an important factor. The eventual failures were generally manifest by internal cracks growing transverse to the loading direction. A variety of experimental analyses indicate that this failure is primarily thermal, in that the temperature rise due to viscous dissipation eventually leads to a melting of the hard segment domains which act to reinforce the material. No strong indication of thermal or thermomechanical bond scission was obtained, although a progressive reduction in the rubbery modulus was noted.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760270206
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  • 9
    Electronic Resource
    Electronic Resource
    Relationships in a bismaleimide resin system. Part I: Cure mechanisms (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 409-414 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: A series of bismaleimide resin systems has been examined in order to identify the molecular features responsible for the mechanical response of these materials. A range of network structures was produced both by formulation of resins with different ratios of N,N′-bismaleimido-4,4′-diphenylmethane (BMI) and methylene dianiline (MDA), and by the use of different thermal processing cycles. Spectrographic and chromatographic techniques were used to study the reactions that occurred during the cure. Two principal reactions were confirmed: a Michael addition reaction which provides linear chain growth, and an addition reaction which produces crosslinking through the double bonds of the maleimide group. In general, curing at a lower temperature or increasing the MDA content served to favor chain extension over crosslinking, which might be expected to increase molecular mobility in the resin.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760320604
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  • 10
    Electronic Resource
    Electronic Resource
    Relationships in a bismaleimide resin system. Part II: Thermomechanical properties (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 415-420 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: A range of bismaleimide resins of differing network structure was produced both by varying the ratios of N,N′-bismaleimido-4,4′-diphenylmethane (BMI) and methylene dianiline (MDA), and also by the use of different thermal processing cycles. Characterization of the resins by a variety of mechanical, physical, and micrographic techniques showed that properties such as modulus and yield strength varied directly with crosslink density and its associated free volume. Fracture toughness was found to increase as the crosslink density decreased, and microscopic investigation of the resin fracture surfaces identified characteristics which correlated with the resin fracture toughness.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760320605
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