Resolution of Crystalline Phases in Polymorphic Gel-spun Ultra-high Molecular Weight Polyethylene Fibers Using Restrained Differential Scanning Calorimetry and X-ray Diffraction PDF Download
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Author: Amos Wampler
Publisher: ProQuest
ISBN: 9780549756972
Category : Calorimetry
Languages : en
Pages :
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Book Description
Characterizing highly oriented ultra-high molecular weight polyethylene (UHMWPE) fibers can present a challenge at or near melt temperatures. The fibers tend to shrink, creating difficulties during testing, both from excessive noise and from the possible alteration of morphology. Perturbations arise during standard differential scanning calorimetry (DSC) and limit the use of an easily accessible laboratory technique. Restraining the fibers during testing, however, suppresses these perturbations and permits the clear determination of melting events as the fiber is subjected to increasing temperatures. This technique is compared to x-ray diffraction (XRD) as a second measure of crystallinity at ambient temperature, removing the concern of shrinking and reorientation during the test.
Author: Amos Wampler
Publisher: ProQuest
ISBN: 9780549756972
Category : Calorimetry
Languages : en
Pages :
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Book Description
Characterizing highly oriented ultra-high molecular weight polyethylene (UHMWPE) fibers can present a challenge at or near melt temperatures. The fibers tend to shrink, creating difficulties during testing, both from excessive noise and from the possible alteration of morphology. Perturbations arise during standard differential scanning calorimetry (DSC) and limit the use of an easily accessible laboratory technique. Restraining the fibers during testing, however, suppresses these perturbations and permits the clear determination of melting events as the fiber is subjected to increasing temperatures. This technique is compared to x-ray diffraction (XRD) as a second measure of crystallinity at ambient temperature, removing the concern of shrinking and reorientation during the test.
Author:
Publisher:
ISBN: 9780803124820
Category : Materials
Languages : en
Pages : 137
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Book Description
Author: Jie Gao
Publisher:
ISBN:
Category : Colloids
Languages : en
Pages : 82
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Book Description
Molecular organogels are thermo reversible quasi-solid materials, which are formed by low molecular weight organogelators (LMOGs) undergoing supramolecular aggregation via non-covalent interactions, forming a three-dimensional fibrillar network. Numerous applications of molecular organogels are been investigated as edible oils, drug release matrices and personal care products. The chemistry of the organic phase (i.e., solvent) influences every level of structure in organogels. Different solvents induce LMOG to assemble into "crystal like" fibers, which have more than one crystal form, lamellar arrangement and domain size. Differences in these solid states are known to affect the macroscopic properties of the gel, including critical gelator concentration (CGC), melting point, melting enthalpy and opacity.12-hydroxystearic acid (12HSA) was examined in several classes of organic solvents with different function groups. These gels, sols or precipitates were analyzed using a series of techniques including: powder x-ray diffraction (XRD), differential scanning calorimetry (DSC), fourier-transform infrared spectroscopy (FT-IR), pulsed nuclear magnetic resonance spectroscopy (pNMR) and microscopy. Specifically, certain solvents caused 12HSA to self-assemble into a triclinic parallel polymorphic form with subcell spacing of ~4.6, 3.9, and 3.8 Å and an interdigitated unit cell with a lamellar arrangement (38~44 Å). This polymorphic form corresponded to a less effective sphereultic supramolecular crystalline network, which immobilizes solvents at CGC greater than 1.5 wt %. The other group of solvents induce a hexagonal subcell spacing (i.e., unit sub cell spacing ~4.1 Å) and are arranged in a multi lamellar fashion with a unit cell greater than the bimolecular length of 12HSA (~54 Å). This polymorphic form corresponds to fibrillar aggregates with a CGC less than 1 wt %.
Author: Qipeng Guo
Publisher: John Wiley & Sons
ISBN: 1118452151
Category : Technology & Engineering
Languages : en
Pages : 472
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Book Description
With a focus on structure-property relationships, this book describes how polymer morphology affects properties and how scientists can modify them. The book covers structure development, theory, simulation, and processing; and discusses a broad range of techniques and methods. • Provides an up-to-date, comprehensive introduction to the principles and practices of polymer morphology • Illustrates major structure types, such as semicrystalline morphology, surface-induced polymer crystallization, phase separation, self-assembly, deformation, and surface topography • Covers a variety of polymers, such as homopolymers, block copolymers, polymer thin films, polymer blends, and polymer nanocomposites • Discusses a broad range of advanced and novel techniques and methods, like x-ray diffraction, thermal analysis, and electron microscopy and their applications in the morphology of polymer materials
Author: Wenbing Hu
Publisher: Springer Science & Business Media
ISBN: 3709106702
Category : Technology & Engineering
Languages : en
Pages : 248
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Book Description
A molecular view on the fundamental issues in polymer physics is provided with an aim at students in chemistry, chemical engineering, condensed matter physics and material science courses. An updated translation by the author, a renowned Chinese chemist, it has been proven to be an effective source of learning for many years. Up-to-date developments are reflected throughout the work in this concise presentation of the topic. The author aims at presenting the subject in an efficient manner, which makes this particularly suitable for teaching polymer physics in settings where time is limited, without having to sacrifice the extensive scope that this topic demands.
Author: Cristina Prisacariu
Publisher: Springer Science & Business Media
ISBN: 3709105145
Category : Technology & Engineering
Languages : en
Pages : 255
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Book Description
A comprehensive account of the physical / mechanical behaviour of polyurethanes (PU ́s) elastomers, films and blends of variable crystallinity. Aspects covered include the elasticity and inelasticity of amorphous to crystalline PUs, in relation to their sensitivity to chemical and physical structure. A study is made of how aspects of the constitutive responses of PUs vary with composition: the polyaddition procedure, the hard segment, soft segment and chain extender (diols and diamines) are varied systematically in a large number of systems of model and novel crosslinked andthermoplastic PUs. Results will be related to: microstructural changes, on the basis of evidence from x-ray scattering (SAXS and WAXS), and also dynamic mechanical analyses (DMA), differential scanning calorimetry (DSC) and IR dichroism. Inelastic effects will be investigated also by including quantitative correlations between the magnitude of the Mullins effect and the fractional energy dissipation by hysteresis under cyclic straining, giving common relations approached by all the materials studied. A major structural feature explored is the relationship between the nature of the hard segment (crystallising or not) and that of the soft segments. Crystallinity has been sometimes observed in the commercial PUs hard phase but this is usually limited to only a few percent for most hard segment structures when solidified from the melt. One particular diisocyanate, 4,4’-dibenzyl diisocyanate (DBDI) that, in the presence of suitable chain extenders ( diols or diamines), gives rise to significant degrees of crystallinity [i-iii] and this is included in the present work. Understanding the reaction pathways involved, in resolving the subtle morphological evolution at the nanometre level, and capturing mathematically the complex, large-deformation nonlinear viscoelastic mechanical behaviour are assumed to bring new important insights in the world basic research in polyurethanes and towards applied industrial research in this area.
Author: Elena Borisenko
Publisher: BoD – Books on Demand
ISBN: 9533076089
Category : Science
Languages : en
Pages : 346
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Book Description
Crystal growth is an important process, which forms the basis for a wide variety of natural phenomena and engineering developments. This book provides a unique opportunity for a reader to gain knowledge about various aspects of crystal growth from advanced inorganic materials to inorganic/organic composites, it unravels some problems of molecular crystallizations and shows advances in growth of pharmaceutical crystals, it tells about biomineralization of mollusks and cryoprotection of living cells, it gives a chance to learn about statistics of chiral asymmetry in crystal structure.
Author: Aravind Dasari
Publisher: Springer
ISBN: 1447168097
Category : Technology & Engineering
Languages : en
Pages : 305
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Book Description
This highlights ongoing research efforts on different aspects of polymer nanocomposites and explores their potentials to exhibit multi-functional properties. In this context, it addresses both fundamental and advanced concepts, while delineating the parameters and mechanisms responsible for these potentials. Aspects considered include embrittlement/toughness; wear/scratch behaviour; thermal stability and flame retardancy; barrier, electrical and thermal conductivity; and optical and magnetic properties. Further, the book was written as a coherent unit rather than a collection of chapters on different topics. As such, the results, analyses and discussions presented herein provide a guide for the development of a new class of multi-functional nanocomposites. Offering an invaluable resource for materials researchers and postgraduate students in the polymer composites field, they will also greatly benefit materials
Author: Rolf Hilfiker
Publisher: John Wiley & Sons
ISBN: 3527607722
Category : Science
Languages : en
Pages : 433
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Book Description
Edited by one of the leading experts in the field, this handbook emphasizes why solid-state issues are important, which approaches should be taken to avoid problems and exploit the opportunities offered by solid state properties in the pharmaceutical and agricultural industries. With its practical approach, this is at once a guideline for development chemists just entering the field as well as a high-quality source of reference material for specialists in the pharmaceutical and chemical industry, structural chemists, physicochemists, crystallographers, inorganic chemists, and patent departments.
Author: Ian W. Hamley
Publisher: John Wiley & Sons
ISBN: 1118681428
Category : Technology & Engineering
Languages : en
Pages : 304
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Book Description
This book provides an introduction to this exciting and relativelynew subject with chapters covering natural and synthetic polymers,colloids, surfactants and liquid crystals highlighting the many andvaried applications of these materials. Written by an expert in thefield, this book will be an essential reference for people workingin both industry and academia and will aid in understanding of thisincreasingly popular topic. Contains a new chapter on biological soft matter Newly edited and updated chapters including updated coverageof recent aspects of polymer science. Contain problems at the end of each chapter to facilitateunderstanding
