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  • 1
    Electronic Resource
    Electronic Resource
    Craze development in poly(methyl methacrylate) during stable fatigue crack propagation (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 833-842 
    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: In order to obtain a more complete understanding of failure mechanisms in glassy polymers subjected to fatigue loading conditions, craze zone dimensions (i.e., length and thickness at the crack tip) were measured simultaneously with fatigue crack propagation data in poly(methyl methacrylate) (PMMA) by optical interferometry. Since the craze shape was observed to assume a wedge-shaped configuration similar to the one described by the Dugdale plastic strip model, crazing stresses were inferred on the basis of this model. When varying the stress ratio (R = minimum load/maximum load) of the applied cyclic load in the range from 0.1 to 0.7, it was found that both craze length and craze thickness are essentially independent of the R-ratio and can be correlated in terms of the maximum stress intensity factor only. On the other hand, significant variations in craze dimensions with test frequency occurred over the range from 0.1 to 250 Hz. The results are discussed in terms of the viscoelastic nature of the material and a competition between the effects of strain rate and hysteretic heating.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241014
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of short glass fibers and particulate fillers on fatigue crack propagation in polyamides (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 982-987 
    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 fatigue crack propagation (FCP) behavior (at 10 Hz) of several commercial short-glass-fiber and mineral-reinforced nylon composites has been investigated. The FCP rates can be described in terms of the well-known Paris relationship. Significant improvement in FCP performance was found for the glass-fiber-reinforced materials in comparison to that of the pure matrix materials (nylon 66 and nylon 612). Also, the FCP resistance was found to increase with increasing fiber content and interfacial adhesion for nylon 66. Despite the fact that specimens were cut from injection-molded plaques, no or only slight effects of orientation were observed by testing specimens with cracks growing parallel and perpendicularly, respectively, to the major flow direction. Electron microscopy studies of fracture surfaces revealed a complex pattern of fiber orientation, varying over the plaque thickness and consisting of layers with fibers oriented mainly parallel, perpendicularly, or randomly to the major flow direction; nevertheless, the specimens behaved quasi-isotropically. Significant differences in fracture mechanism were observed, depending on the matrix, the interfacial bonding, and the crack speed. In contrast to the fiber-rein forced nylons, the mineral-reinforced material exhibited poorer FCP resistance than neat nylon 66, even though the former is superior in tensile and impact behavior.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221513
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  • 3
    Electronic Resource
    Electronic Resource
    Applicability and limitations of current lifetime prediction models for thermoplastics pipes under internal pressure (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 247 (1997), S. 131-145 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Engineering thermoplastics, in particular polyolefins such as special grades of poly(ethylene), are gaining importance in pipe applications such as gas and water supply systems. To ensure proper performance of such pipes over the required lifetime, polymer physics and mechanics concepts are needed to adequately account for the effects of time, temperature, and environmental conditions as well as the occurrence of pipe defects and imperfections on relevant polymer properties and pipe performance. This article provides a critical overview of the scientific background of current methodologies to describe the long-term behavior of thermoplastic pressure pipes. In particular, the merits and limitations of two different approaches-namely, the standard extrapolation method (SEM) described in ISO/TR 9080 and the linear elastic fracture mechanics (LEFM) approach-are compared. Special attention is given to effects associated with material ageing and degradation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052470109
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  • 4
    Electronic Resource
    Electronic Resource
    The use of collagen-based model peptides to investigate platelet-reactive sequences in collagen (1996)
    New York : Wiley-Blackwell
    Biopolymers 40 (1996), S. 383-397 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simple collagen-like peptides comprising a repeat Gly-Pro-Hyp sequence are highly platelet-reactive when presented to platelets in triple-helical and polymeric form. This activity is not mediated by the platelet collagen receptor integrin α2β1. This may imply the existence of an intrinsic platelet reactivity associated with the collagen triple helix as such or perhaps that the Gly-Pro-Hyp sequence in collagen serves as a specific cell-recognition site. In our view this basic α2β1-independent reactivity is modulated by the presence in collagen of sequences that may either enhance or diminish the interaction with platelets. Inhibition studies with short linear peptides have allowed the tentative identification of sequences in collagen such as XPGEP(Q)GPX and D(N)GE(Q)X that may promote the activation of platelets and so enhance collagen-platelet interaction. Sequences serving as integrin α2β1-binding sites may also promote platelet reactivity by permitting interaction with the collagen receptor. Using triple-helical peptides based on the sequence of the platelet-reactive collagen type III fragment α1(III)CB4, we have been able to locate an α2β1-binding site in collagen type III within a 30-mer sequence representing residues 508-537 of the α1(III) constituent α-chain. Despite their α2β1-independent platelet reactivity, signalling by the (Gly-Pro-Hyp)n-based peptides shows many features in common with signalling by collagen fibers, including activation of p72SYK and p125FAK the latter of which has until now been considered a specific consequence of ligand binding to α2β1. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Gruneisen parameter for polyamides (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1927-1935 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For the five aliphatic polyamides, poly(caprolactam), poly(ω-aminoundecanoic acid), poly(ω-aminododecanoic acid), poly(hexamethylene adipamide), and poly(hexamethylene sebacamide), experimental values were obtained of the thermodynamic properties: molar volume, volume thermal expansion coefficient, isothermal bulk modulus, and molar heat capacity. These properties were combined to form the dimensionless ratio known as the Gruneisen parameter. All of the experimental properties were analyzed in terms of molecular components using the method of additive properties. It was concluded that the hydrogen bonding found in polyamides produces a highly localized region of very low Gruneisen parameter.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840919
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation of ion-containing elastomers by emulsion copolymerization of dienes with olefinic sulfonic acid salts (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 1027-1037 
    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: Procedures were developed for the emulsion copolymerization of either butadiene or isoprene with several different water-soluble monomers containing sulfonic acid salt groups, primarily with sodium styrenesulfonate, for the preparation of ionomer elastomers. By the use of a nonionic surfactant and a two-component redox initiator, which was based on a water-soluble reducing agent and a hydrophobic peroxide, copolymers with sufficient amounts of the ionic monomer could be prepared. Unusual effects of conversion on rate, copolymer composition, and molecular weight were observed and attributed to special effects caused by the ionic monomers. The copolymers were soluble in mixed hydrocarbon-alcohol solvent systems.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260325
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of molecular weight on fatigue crack propagation in nylon 66 and polyacetal (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1707-1717 
    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 influence of molecular weight on fatigue and fracture behavior in nylon 66 (N66) and polyacetal (PA) is examined. Fatigue crack propagation (FCP) resistance and apparent fracture toughness (Kcf) in these two semicrystalline polymers increase with increasing molecular weight in a manner consistent with that reported for another semicrystalline polymer (HDPE) as well as for several amorphous polymers. The improved FCP resistance with increasing molecular weight is attributed to the development of a molecular entanglement network that more effectively resists cyclic-load-induced breakdown. A type of discontinous crack growth is identified in PA at 100Hz and in N66 (2.6% H2O) at 50 Hz and compared with that observed in amorphous polymers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270527
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  • 8
    Electronic Resource
    Electronic Resource
    Poly-3-Hydroxyalkanoates containing unsaturated repeating units produced by pseudomonas oleovorans (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1367-1374 
    Details
    ISSN: 0887-624X
    Keywords: poly-β-hydroxyalkanoates ; bacterial polyesters ; Pseudomonas oleovorans ; functional polyesters ; reserve polyesters ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly-3-hydroxyalkanoates (PHAs) containing repeating units with terminal alkene substituents at the 3-position were produced by Pseudomonas oleovorans grown with either 7-octeneoic acid [OA(=)] alone, or 10-undeceneoic acid [UND(=)] alone, or mixtures of UND(=) and either nonanoic acid (NA) or octanoic acid (OA). For the latter, the biomass and PHA yields decreased as the fraction of UND(=) increased in the mixed carbon substrates. Essentially all of the repeating units in the PHA obtained from cells grown with UND(=) alone contained terminal alkene groups, including 3-hydroxy-10-undeceneoate, 3-hydroxy-8-noneneoate, and 3-hydroxy-6-hepteneoate units, but less than half of the units in the PHA from OA(=) had alkene substituents. The PHAs obtained from cells grown with various mixtures of UND(=) and either OA or NA were random copolymers, and the fraction of units with alkene substituents in these polymers increased in proportion to the fraction of UND(=) in the mixed carbon substrates. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330819
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  • 9
    Electronic Resource
    Electronic Resource
    Sulfonation of a poly(phenylquinoxaline) film (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1197-1199 
    Details
    ISSN: 0887-624X
    Keywords: sulfonation ; proton exchange membrane ; poly(phenylquinoxaline) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamics of semibatch polymerization reactors: II. Pilot-plant study (1997)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 157-165 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A semibatch flow scheduling strategy proposed by Teymour and Ray (1989, 1996) is evaluated for a polymerization reaction conducted in a pilot-plant reactor. The reaction used is the free radical terpolymerization of styrene, α-methyl styrene, and acrylic acid monomers initiated by an organic peroxide initiator and carried out in the presence of a reactive glycol ether solvent. This strategy was tested in both single batch and sequential semibatch modes. The process was shown to produce polymer of constant molecular weight properties and composition as inferred from acid number and monomer conversion measurements. This process could be used for obtaining polymer products from a semibatch reactor that are of comparable quality to CSTR products. Results indicate success of this process at meeting this objective; however, practical considerations relating to agitation and temperature control need to be properly addressed to ensure this success.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690430118
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