Materials Literature
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Abstract Shrinkage force measurements on drawn polyethylene terephthalate fibres have been evaluated in terms of the elastic behaviour of a molecular network. It is shown that for low network deformations the classical theory of Kuhn and Grün describes the stress‐optical behaviour very well. For high deformations, the…
Abstract Cotton, linen, polynosic rayon, standard rayon, nylon 6, and poly(ethylene terephthalate) (PET) fibers were treated with low temperature plasmas of O 2 , N 2 , Ar, CF 4 , and CO. The relative free‐radical intensities obtained by ESR spectra increased in the following order: linen > cotton > polynosic ra…
Abstract A theory is developed for predicting the solvent self‐diffusion coefficient in a crosslinked, amorphous polymer. The theory is based on a modification of the free‐volume theory of transport for the presence of crosslinks in the polymer. The general predictions of the theory for the variations of the self‐diff…
Abstract Mark–Houwink constants for polyacrylamide and poly(acrylamide‐ co ‐sodium acrylate) in 0.2M Na 2 SO 4 were measured using eight fractionated samples of polyacrylamide and 26 hydrolyzed polyacrylamide samples. The dependence of K and a on the copolymer compositions was found for the range of acrylate content 6…
Abstract Classical morphological analysis has been performed on novel PET fibers of high modulus and low shrinkage (HMLS). As expected, amorphous orientation controls the degree of shrinkage and tenacity. The uniqueness of these materials is derived from a high “effective” crosslink density which results in a high ret…
Abstract XPS, SEM, SSIMS, FTIR‐ATR, water‐in‐air, and air‐in‐water contact angle measurements have been used to unambiguously characterize the locus of failure of PP/epoxy joints. In the case of untreated PP, the fracture has been found adhesive, whereas in oxygen plasmatreated PP, it is cohesive, within bulk PP, but…
A two-state, four-orbital, independent electron analysis of the first optical molecular hyperpolarizability, beta, leads to the prediction that |beta| maximizes at a combination of donor and acceptor strengths for a given conjugated bridge. Molecular design strategies that focus on the energetic manipulations of the b…
This book, together with its companion volume The Science of Crystallization: Macroscopic Phenomena and Defect Generation, make up a complete course that will teach an advanced student how to understand and analyse scientifically any of the phenomena that are observed during natural or technological crystallization fr…
The new world of textile technology now encompasses realms of products that were not even dreamed of ten years ago. Hightech textiles are prevalent as major components in such diverse products as artificial organs, structural bone replacements, rocket motors and nozzles, space shuttle shields, the Stealth bomber and m…
The fabric geometric model based on a stiffness averaging method is utilized to analytically characterize two-step braided composites. The fiber architecture of the braided preform is investigated by identifying the geometric and braiding parameters which include the linear density ratio between axial and braider yarn…
Abstract The effect of the annealing temperature on the structure of unoriented polyamide 6 was studied by swelling in methanol and small‐angle X‐ray scattering. The observed values of mean‐square fluctuations of scattering density can be explained by using a model with an inhomogeneously swelling amorphous phase. An…
Abstract CHClF2 has been found to be effective as a surface treatment agent of SiO2–Al2O3 and Al2O3, as well as chlorofluorocarbons (CFCs) such as CCl2F2 and CClF3, to enhance its catalytic activity and/or activity maintenance for the alkylation of benzene with propene. The CHClF2-treatment may be performed at tempera…
It is proposed in this work, to evaluate experimentally: thermal diffusivity, or, and thermal conductivity, k, of poorly conductive materials. The method selected is based on transient heat conduction in solid media and seeks to determine the conditions under which the power series solution characterizing the transien…
Abstract Conformation of viologen-linked porphyrins (p-PCnV, n=4–7), which are capable of intramolecular electron transfer, was studied by 1H NMR in order to gain insight into the relative geometry of the donor and acceptor during the electron transfer process. The orientation of the viologen with respect to the porph…
Three photographic studies are presented which capture the behaviour of material specimens as they are taken to and beyond their failure point by impact and other loading conditions. One is of a polymer sphere impacting onto a rigid flat surface and depending upon the impact velocity, the sphere can fail in different…
The thermodynamic interaction parameter, χφ, for a low-density polyethylene in p-xylene, ethylbenzene, and n-octane has been determined over a range of segment fraction, φ2, from 0.2 to 0.7 using the melting point depression method. Taking advantage of a unique feature of polyethylene, a new procedure has been propose…
In situ laser deposition was used to fabricate YBa 2 Cu 3 O 6.8 (YBCO) films on amorphous glasses. Yttrium stabilized zirconia (YSZ) and conducting indium-tin-oxide (ITO) were used as the buffer layers to improve the transport properties of YBCO films. There was negligible interdiffusion occurring at the interfaces. Y…
Chemical behavior of nitrogen species in intense radiation fields was studied. Simulation models and a N/H/O reaction scheme were developed and verified with a series of experiments. The following results and suggestions were obtained: 1. Ammonium formation rates in water pressurized with H2 and N2 gases at temperatur…
In order to protect them from environmental degradation, as well as to increase their reflection efficiency in some instances, metallic gratings are often coated with dielectric materials. This practice introduces the effects of waveguide modes in the reflection characteristics. Here, we study the alteration of the pl…
The intermediate phase of the aluminate sodalite Ca8[Al12O24](WO4)2, stable between 653 and 617 K, has been studied by X-ray single crystal, X-ray powder and neutron powder methods, and its structure determined. The phase is difficult to detect by diffraction methods, mainly because of its similarity with the cubic ph…