Unwinding of spherulites in polymers

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WebPolymer Spherulites. D.C. Bassett, in Encyclopedia of Materials: Science and Technology, 2002 4 Spherulitic Textures. Spherulites are not unique entities but have textures varying … WebAug 19, 2006 · Morphology of polyethylene spherulites has been investigated by the low-dose technique using transmission electron microscopy (TEM) in a scanning mode for …

The spherulitic structure of crystalline polymers. Part I ...

In polymer physics, spherulites (from Greek sphaira = ball and lithos = stone) are spherical semicrystalline regions inside non-branched linear polymers. Their formation is associated with crystallization of polymers from the melt and is controlled by several parameters such as the number of nucleation sites, structure of the polymer molecules, cooling rate, etc. Depending on those parameters, spherulite diameter may vary in a wide range from a few micrometers to milli… pheromone men\\u0027s fragrances \\u0026 aftershaves

APS -APS March Meeting 2024 - Event - Spherulites, Cylindirtes …

WebCrystallinity refers to the degree of structural order of a solid. In a crystal, the arrangement of atoms or molecules is consistent and repetitive. Many materials such as glass ceramics and some polymers can be prepared in such a way as to produce a mixture of crystalline and amorphous regions. Crystallisabilty • Crystallisabilty is the ... WebSep 2, 2016 · 1. Introduction. Using gallstone spherulite crystals as models for covering all spherulites of organic compounds or polymers, Burns [] illustrated relationships between stresses and cracks.Spherulites in general have spherical symmetry, but crystal properties are anisotropic in the radial and tangential directions. WebMar 21, 2024 · Morphology of semicrystalline polymers on the super-µm scale, spherulites, shish-kebabs, and cylindrites, strongly affects the mechanical and other material properties. Current imaging techniques give only a 2D picture of these objects, whose features in the 3rd dimension have been assumed rather than observed. pheromone mann

Banding in Spherulites of Polymers Having Uncompensated Main …

Transparent semi‐crystalline polymeric materials and their ...

WebFeb 21, 2008 · Spherulite ring-band patterns and growth regimes in neat poly(ɛ-caprolactone) (PCL) and its miscible blends were analyzed using polarized-light optical microscopy and differential scanning calorimetry (DSC). Spherulite growth in thin-film forms and transformation of spherulite patterns in different regimes were investigated by … WebJul 1, 2005 · This highly non-equilibrium process leads to an extraordinary variety of polycrystalline growth patterns that are broadly termed 'spherulites' because of their large-scale spherical shape. Despite the prevalence and practical importance of spherulite formation, only rather qualitative models of this phenomenon exist. The present work … pheromone manufacturerWebApr 29, 2015 · Polymer Journal - The melt memory of isotactic polystyrene spherulites from the melt is investigated using optical microscopy. When the melting–recrystallization … pheromone mean

"WebThe extinction patterns between crossed nicols shown by two types of arrays of uniaxial crystals have been investigated. The arrays were (a) a disk whose radii were twisted … " - Unwinding of spherulites in polymers

Unwinding of spherulites in polymers

Spherulites - an overview ScienceDirect Topics

WebAug 20, 2024 · Polymer Morphology in 3D. Common plastics like polyethylene, polypropylene and Nylon crystallize during melt-processing. Their thin lamellar crystals … WebMany structural materials (metal alloys, polymers, minerals, etc.) are formed by quenching liquids into crystalline solids. This highly nonequilibrium process often leads to polycrystalline growth patterns that are broadly termed "spherulites" because of their large-scale average spherical shape. De …

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WebThe extinction behavior of spherulites in many polymers and nonpolymers is shown to result from a characteristic twisting of crystal orientation acquired during growth. Extinction … WebDec 7, 1999 · The study of twisting crystalline orientation in banded polymer spherulites has recently been revitalized by availability of optically active macromolecules that crystallize …

WebSep 1, 1999 · The morphology of spherulites shows that they form because of a short-range force operative at the branch points of dominant lamellae causing them to diverge at non … WebAn investigation on polymer spherulites is being described in three parts. Part I (the present paper) describes the various effects observed under the polarizing microscope. These are …

WebAn investigation on polymer spherulites is being described in three parts. Part I (the present paper) describes the various effects observed under the polarizing microscope. These are interpreted in terms of the concepts of crystal optics; the problem of the position of the molecules and that of the microscopic fine structures will form Parts II and III. WebNov 13, 2015 · The addition of the whole wave plate (upper photomicrograph) confirms the tangential arrangement of the polymer chains. The banding occuring in these spherulites indicates slow cooling of the melt allowing the polymer chains to grow out in spirals. This information on thermal history is almost impossible to collect by any other technique.

Webfor a special polyethylene studied, that the spherulites deform affinely at least up to 60-% elongation. It was also indicated that the spherulite deformation model of the multiple con

WebMagnetically Aligned DNA Liquid Crystals 22 Transition region between cholesteric and high density liquid crystalline DNA. Orientation of the transition region with a 5 Tesla magnetic field increases the helical pitch of the unwinding cholesteric mesophase, which is spontaneously forming batonnets during the phase transition as is evident in the image … pheromone massage oilWebpolymer single crystals grown from dilute solution. Electron diffraction data suggest that relatively large regions of the spherulite correspond to single crystals. A growth … pheromone men\\u0027s fragrances aftershavesWebMay 1, 2016 · Spherulites appear in a wide range of material systems. They can be found in nearly all crystallizable organic polymers (see Geil [3] for an early collection of examples), as well as in polymeric selenium [4], [5].Spherulites are also formed by small organic … pheromone mind controlWebgated polymers or small molecules on crystalline 1,3,5-trichlo- robenzene (TCB) from the melt, [15] or directly from solution, [16] resulting in larger macroscopic spherulitic … pheromone men\u0027s fragrances aftershavesWebJul 15, 2024 · Affiliations 1 Graduate Institute of Biomedical Engineering, Chang Gung University, Taoyuan 33302, Taiwan, ROC.; 2 Graduate Institute of Biomedical Engineering, Chang Gung University, Taoyuan 33302, Taiwan, ROC; Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, Taoyuan 33305, Taiwan, ROC; Department of Materials … pheromone mistWebC.-H. Tu, et al. Macromolecules (2024) Book Chapter (Invited) Polymers under 2-D Confinement: Flow of Polymer Melts at the Nanoscale (Chapter 9) C.-H. Tu, et al. ACS Symposium Series (2024) In situ nanodielectric spectroscopy. Increasing adsorption during imbibition of polymer melts inside nanopores evidenced by two-stage time evolution of ... pheromone midnightWeblamellar crystals of polymers other than polyethylene also exhibited chain folding. More than that, chain fold-ing was an essential feature of the crystallization of polymers from the molten state. In the latter case, poly-mers were found to undergo spherulitic crystallization, but the spherulites were composed of radiating struc- pheromone molecule