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.
This paper describes a new route for the manufacture of single polymer composites by combining the processes of hot compaction and film stacking. Assemblies of oriented fibres and tapes, were produced with and without an interleaved film of the sample polymer type, over a range of processing temperatures. Of particular interest was to choose temperatures so that in some cases only the interleaved...
Observations of individual lamellae within spherulites of linear polyethylene, drawn under affine conditions between room temperature and ∼100 °C, show lamellae surviving to sample failure, thereby providing a strong memory of the initial morphology in the final product. Lamellae rotate and deform according to the angle their plane makes with the draw direction. Those parallel to the draw direction...
A number of polyurethanes are synthesized, based on the novel diisocyanate 4,4'-dibenzyl diisocyanate (DBDI), the traditional 4,4'- methylene bis(phenyl isocyanate) (MDI), or combinations of these. Two equivalent series are prepared, one with hydroxyterminated poly(ethylene adipate) and one with poly(tetrahydrofuran) macrodiol. Mechanical measurements and X-ray crystallinity data are shown for the...
The morphology of woven oriented polypropylene tapes and fibres has been studied both before and after processing by hot compaction. In this technique bundles of oriented tapes or fibres are subjected to suitable conditions of temperature and pressure so that just sufficient of each tape or fibre is selectively melted; on cooling, this material recrystallizes to bind the whole structure together....
The development of morphology in tapes and woven cloths of oriented melt-spun Tensylon polyethylene has been studied both before and after hot compaction over a range of temperatures below and above the optimum. For both the unidirectional fibres and the woven cloths, the optimum temperature was found to be where approximately 30% of the original structure was lost which, for Tensylon tapes, was ~2K...
Two series of semiflexible aromatic copolyesters have been prepared and studied. In the first series, the relative proportion of a biphenyl and a phenyl unit was varied through copolymerisation; in the second, the phenyl ring system was further substituted with an aliphatic side-chain, in order to promote additional disruption to any solid-state ordering. These copolymers have been characterised experimentally...
Specimens of the polyethylene Sclair 2907, full of large banded spherulites, have been drawn to high extensions, and parts of these annealed close to their melting points under constraint. Etching with permanganic reagents and examination under the scanning electron microscope revealed that in transverse sections of the unannealed specimens, the legacy of the banded spherulitic morphology is seen...
In-situ synchrotron wide angle X-ray diffraction (WAXD) was used to follow crystallization in a polydisperse isotactic polypropylene during and after a brief interval of shear under isothermal conditions. A specific flow history was selected from the range that induces a highly oriented skin core morphology (Kumaraswamy G, Issaian AM, Kornfield JA. Macromolecules 1999;32:7537.). At the chosen crystallization...
Morphological investigations on a range of polyethylenes, which differ with respect to their molecular weight characteristics and which possess quite distinctly different superstructures, non-spherulitic and banded spherulitic, have been performed to follow structural developments during drawing. Of particular significance is the detailed examination of transverse sections, in addition to the more...
A particular aromatic polyesteramide with flexible spacers has been shown to crystallize into a variety of spherulitic forms whose birefringence varies markedly with crystallization temperature. However, a temperature step crystallization technique allows the unambiguous recognition of the different forms in spite of the varying birefringence. Though their appearance under optical and electron microscopy...
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.