Preliminary Studies of the Fractography of Fibers and Other Polymeric Materials in the Scanning Electron Microscope

McKee, Anthony; Beattie, C.L.

doi:10.1177/004051757004001108

Cited by 14 publications

(6 citation statements)

References 2 publications

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“…39 While examination of the overall morphology of supramolecular IPNs in the unstressed state provides some insight into the connection between IPN morphology and mechanics, it is expected that, upon imposing stress on an elastomer-toughened material with a phase-separated structure, various toughening mechanisms may occur to enhance energy dissipation. 21 We utilized fractography, which is a morphological study of the damage zone after failure in a mechanical test, 40 to enhance our understanding of the mechanisms of mechanical toughness enhancement in the supramolecular IPNs.…”

Section: Phase Morphologymentioning

confidence: 99%

Exploring the Role of Supramolecular Associations in Mechanical Toughening of Interpenetrating Polymer Networks

Monemian

Korley

2015

Macromolecules

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Model "supramolecular IPNs" were developed via the formation of a hydrogen-bonded, supramolecular network of 2-ureido-4-[1H]-pyrimidinone (UPy) telechelic poly(ethylene-co-1-butene) (SPEB) in the presence of photopolymerizable, hydroxyl-terminated polybutadiene (HTPB). The role of a supramolecular elastomeric phase in mechanical toughening of IPNs was explored through (1) dynamic dissociation and reassociation of the noncovalent, UPy supramolecular associations, and (2) interphase formation. While an ∼4× increase in tensile toughness of the HTPB matrix was observed through incorporation of 10 wt % ethylene−propylene rubber (EPR)as a conventional elastomeric toughening agentinto HTPB, it was shown that adding the same amount of supramolecular elastomer SPEB to HTPB led to ∼600× enhancement in tensile toughness. Strain rate-dependent mechanical response and fractography studies revealed that this dramatic toughness enhancement was due to dissociation/reassociation of the dynamic UPy linkages in the elastomeric phase that facilitated dilatational yielding of the IPN. This toughness enhancement was only observed in combination with the existence of strong interfacial coupling between the matrix and supramolecular phase as revealed by transmission electron microscopy and dynamic mechanical analysis. By exploiting noncovalent dynamics and interfacial control in interpenetrating networks, pathways are envisioned toward a new class of tough materials.

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Section: Phase Morphologymentioning

confidence: 99%

Exploring the Role of Supramolecular Associations in Mechanical Toughening of Interpenetrating Polymer Networks

Monemian

Korley

2015

Macromolecules

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“…Twenty of the fibres were prepared by Ooating them in a commercial antistatic agent (Bevaloid) and then drying. This method was used by McKee and Beattie (1970) in their study of loop and knot tensile failure. The other twenty fibres were coated with a thin layer (about 200 A) of gold-palladium in a sputter coater,…”

Section: Methodsmentioning

confidence: 99%

“…The compression of knots and loops of acrylic, polyamide, and polyester fibres (McKee and Beattie, 1970), the deformation of yam and fabric structures in abrasion and snagging (Varela et al, 1975), and the deformation of staple-fibre yams (Chenge/a/., 1975) were studied by means of compressive Gharehagfioji, Johnson, and Wanf; and tensile stages. Examination of fibres in knot and loop configurations revealed splitting along a saddle, which might lead to a complex network of fibrils.…”

Section: Introductionmentioning

confidence: 99%

Wool Fibre Microdamage Caused by Opening Processes. Part IV: In-situ SEM Studies on the Compressive Microdamage and Failure of Wool Fibres Looped around Opening Elements

Gharehaghaji

Johnson²,

Wang

1999

The Journal of The Textile Institute

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The compressive behaviour of wool fibre looped around an opening element was studied under quasi-dynamic conditions by using a compressive stage inside an SEM chamber. Reai-time images ofthe microdamage imposed upon the fibre were monitored and recorded during the compression. This study shows that test fibres experience large compressive deformations in tbe contact area. Study of the mechanism of fihre failure through in-situ fractography shows tbat tbe breakage starts from the outer surface of tbe bend and propagates into the compressed surface. The present study also reveals that creep can hide some cracks formed on the surface of the contacted fihre. The failure of wool fihre in contact with a sawtooth and with a pin element is compared and discussed. Tbe likely mechanism of compressive failure of contacted wool fibre is also explored.

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“…10 (1971) / No. 9 With a suitable arrangement of the primary beam, the sample, and the collector, the scanning electron microscope already gives striking three-dimensional pictures. The impression of depth can be increased further by taking proper stereoscopic Unfortunately, for various reasons the measurement of height, as in photogrammetry, is subject to large errors.…”

Section: Applications Of the Scanning Electron Microscopementioning

confidence: 99%

Imaging and Analysis of Surfaces with a Scanning Electron Microscope and Electron Spectrometer

Holm

1971

Angew. Chem. Int. Ed. Engl.

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The topography and the composition of a surface are in many cases of equal importance (catalysis, electroplating, pretreatment of foils and sheet metal, corrosion, passivation, adsorption, coating offibers, etc.) , and this explains the great interest in methods of investigation that reveal both. I f the demands on the resolving power, the analytical possibilities, and the thickness of the surface layer are not too exacting, combined devices like the scanning electron microscope and its analytical accessories can be used. When it is necessary to avoid the compromises involved in simultaneous imaging and analysis, the investigations must be carried out with separate equipment. As an example o f a method for the analysis of surfaces we consider briefly photo-and Auger electron spectroscopy (ESCA). Principle of the Scanning Electron MicroscopeIt has been an old dream of scientists to possess a device enabling them to image a surface with the highest possible spatial resolution, i.e. to study its topography, and in addition to obtain the most complete possible information on the composition of this surface. There is, at present, no such universal apparatus, although numerous attempts have been made using electrons, ions, and X-rays"'. The scanning electron microscope may be considered as a good approximation as regards the demands of microscopy. As a supplement to this we shall discuss a special surface analysis technique which utilizes photo-and Auger electron spectroscopy with X-ray excitation (ESCA). The two methods have, in comparison with others, the advantage that preparation is fairly easy, that they can be used universally, and that they are therefore suitable for routine industrial investigations.[ ' I Dr. R. Holm Farbenfabriken Bayer A. G. 1ng.-Abt. Angewandte Physik SO9 Leverkusen (Germany) [**I Since it is impossible to list the large number of publications dealing with the scanning electron microscope; the reader is referred to the following bibliographies: The scanning electron microscope works on the pantograph principle : The essential elements are two electron beams operated synchronously by a scan generator (Figs. 1 and 2). The primary beam is produced in an evacuated column by thermionic emission, and is focused to a dia- meter of about 1008, by electromagnetic lenses. This beam scans the object point by point and line by line. The other beam records the picture point by point and line by line on the phosphor screen of a cathode ray tube. The magnification is given by the ratio of the picture area to the scanned area of the object.When the primary beam impinges upon the object, a variety of interactions occurs between the electrons and the solid material (Fig. 3). Both secondary electrons and backscattered electrons are used for imaging the surface. The secondary electrons are generated by impact ionization or the Auger effect. They possess a significantly lower energy than the primary electrons and those that are backscattered elastically or with only small energy losses. The secondary elec...

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Preliminary Studies of the Fractography of Fibers and Other Polymeric Materials in the Scanning Electron Microscope

Cited by 14 publications

References 2 publications

Exploring the Role of Supramolecular Associations in Mechanical Toughening of Interpenetrating Polymer Networks

Exploring the Role of Supramolecular Associations in Mechanical Toughening of Interpenetrating Polymer Networks

Wool Fibre Microdamage Caused by Opening Processes. Part IV: In-situ SEM Studies on the Compressive Microdamage and Failure of Wool Fibres Looped around Opening Elements

Imaging and Analysis of Surfaces with a Scanning Electron Microscope and Electron Spectrometer

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