The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Recent advances in quantitative microscopy and low-angle electron diffraction methods have made it possible to probe the fundamental processes of craze fibril formation and craze fibril breakdown. Both the scale of fibrillation within the craze and the magnitude of the crazing stress may be successfully described by a variant of the Taylor meniscus instability process. Within this framework, the key...
This article is concerned with the influence of several significant molecular variables on deformation modes, such as crazing and shear yielding, and on properties and behavior of glassy polymers subject to monotonic or alternating loading. The principal molecular variables to be considered are molecular weight and the extent of chain entlanglement, intra- and intermolecular interactions arising from...
This review summarizes some recent results which demonstrate the susceptibility of glassy polymerdiluent mixtures to exhibit a cavitational mode of plasticity at high stresses and strains in a temperature range close to Tg. The initiation of this mechanism results in extensive stress-whitening of the material. Most of the experiments have been conducted on mixtures of polycarbonate with esters of...
Brittle failure of many thermoplastics is associated with craze formation and governed by craze breakdown. Optical interferometry is a powerful tool for the investigation of this type of plastic deformation in transparent polymers, especially for the measurement of sizes of single crack tip crazes. The results of interferometric measurements are used in connection with fracture mechanics models and...
Crazing is one of the most common fracture precursors in glassy polymers. The structure and properties of crazes are of major interest for polymer fracture. There now exist several powerful experimental techniques such as small angle X-ray scattering or electron microscopy to measure the properties of crazes in polymers, either in the case of isolated crazes or in that of crazes at a moving crack-tip...
This paper deals with the ability of polymers to easily undergo shear deformation and crazing simultaneously at the propagating crack tip. A unique plastic zone, the epsilon plastic zone, reflects this behavior. The epsilon plastic zone has only been observed under sub-critical fatigue crack propagation conditions, i.e., under discontinuous crack growth, where multiple load cycles must occur before...
Glassy polymers of flexible chain molecules with relatively high entanglement molecular weights craze before they undergo general yielding. In unmodified homopolymers such crazing is initiated almost exclusively from surface imperfections which require a relatively high stress to initiate crazes. Under these high stresses, craze matter fracture, initiated from particulate impurities, is rapid and...
Crazing in PP, PE, POM, PA 6, PA 66, PBT, and PEEK has been described in relation to their deformation and fracture behavior. It has been demonstrated that the nature of the damage zone ahead of a notch is governed by the type of stress field: plane stress and plane strain. Plane strain conditions favored by thick sections with notches cause a dilatational stress concentration at the tip of the local...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.