Stress relaxation experiments have been carried out on single filaments of nylon, viscose rayon and acetate rayon over the temperature range 0°C. to -80°C. Similar experiments were also performed on viscose rayon yarns immersed in water at 35°C. In these latter experiments, a marked change in the shape of the stress relaxation curve was noted as the strain was decreased. At strains of the order of 0.05% the relaxation curve had the shape characteristic of a single Newtonian Maxwell element, while the curve obtained at higher elongations could not be explained in terms of a single such element. It was concluded that the flow process involved was non-Newtonian in character. The low temperature results, as well as those obtained previously by Price (20) are discussed In terms of Eyring's hyperbolic tangent equation for describing stress relaxation. / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

Thesis (M.S.)--Ohio University, March, 1989. / Title from PDF t.p.

Th.--Sci. phys.--Clermont-Ferrand 2, 1977. N°: 238.

M.S.

Environmental concerns have brought about a push to replace non-biodegradable products that are made from non-renewable resources. Investigations regarding use of wood fibers and other biomass as a raw material for biodegradable foams and sponges are an example of such a replacement. Foams made at least partially of biomass can be created using cellulose from wood fibers once the cellulose is converted into a fluid form. Polyurethane foams can be made from polyols containing as much as 50% biomass by combined dissolution of wood and starch. Sponges can be made completely from cellulose regenerated from a viscose rayon solution, and the effect of using wood fibers as reinforcement material within the cellulose matrix of such sponges was studied. The effect of fiber content and fiber length on absorbance, swelling, density, air to cellulose ratios, bound water, and tensile was determined.

Thesis (M.S.)--Ohio University, March, 1988. / Title from PDF t.p.

Th. 3e cycle--Instrumentation et mes.--Bordeaux 1, 1983. N°: 1864.

Ce travail, mené dans le cadre d’une thèse CIFRE en collaboration avec le fabricant d’outil de coupe ValeniteSafety et le Laboratoire de Mécanique et Rhéologie EA 2640 de l’Université François Rabelais de Tours (Polytech’Tours), a été réalisé au sein du Centre d’Etude et de Recherche sur les Outils Coupants (CEROC). Il s’agit d’étudier le rayon d’arête noté ER et son influence sur l’intégrité de surface lors d’une opération de tournage à sec sur l’acier 27MnCr5. L’usinage par enlèvement de matière résulte du cisaillement de matière par l' arête de coupe, partie active d’une plaquette. C’est l'élément le plus sollicité pendant la coupe. Une plaquette est caractérisée par son substrat, son revêtement, la géométrie de la zone de coupe et sa micro géométrie d’arête qui influence intimement le cisaillement de la matière. Elle conditionne ainsi l’intégrité de surface usinée. Théoriquement une finition d’arête idéale au bon cisaillement de la matière doit être « vive ». En réalité, dans un grand nombre de cas les arêtes ont un mouchage (arrondie). L’objectif de cette étude est d’analyser le comportement des rayons d’arête. La maîtrise de la finition d’arête peut augmenter de façon significative la durée de vie de la plaquette et assurer la reproductibilité de la qualité de surface usinée. Après un rappel des principes généraux de la coupe, nous nous attachons à décrire la micro géométrie d’arête et son influence lors du procédé d’usinage à sec. Nous présentons ensuite la procédure suivie pour la détermination des conditions d’utilisations de l’outil. Puis nous décrivons les protocoles expérimentaux de préparation des pièces à usiner et des arêtes de coupe de la plaquette. Pour caractériser l’intégrité des surfaces usinées et le comportement des rayons d’arête nous employons plusieurs techniques telles que la Microscopie Electronique à Balayage, la Microscopie Interférentielle, la Micro indentation. Des paramètres tels que les efforts de coupe, les phénomènes d’usures développées pendant les tests de durée de vie, la topographie et la métallurgie de surface ont été analysés. Ces analyses permettent de quantifier le comportement des rayons d’arête et l’influence des tolérances de fabrication sur l’intégrité de surface de la pièce. / This work performed at the Research Cutting Tools Centre “CEROC” has been carried out in the framework of a collaboration with the cutting tool manufacturer ValeniteSafety and the Mechanical & Rheology Laboratory EA 2640 of the University François Rabelais of Tours (Polytech’Tours). It’s devoted to investigate the behaviour of the cutting edge radius denoted ER on the surface integrity of worked piece after dry turning of 27MnCr5 steel. Cutting process involving material removal occurs by a large plastic deformation in a zone of concentrated shear due to the cutting edge. Cutting edge radius is the essential working part of the insert during machining process. An insert is a combination of a substrate, a coating, the geometry of a cutting zone and the edge finish geometry. These parameters related to the shearing property of the worked piece are critical for the quality of the surface integrity. Sharp edge is considered as an ideal edge in theory. However, in many cases, the cutting edges are “honed” on purpose during the manufacturing process of the insert. The aim of this research work is to establish correlations between relevant parameters and examine how the surface integrity of machined steel and tool life can be affected by the cutting tool edge preparation. Control of the micro edge radius geometry can considerably increase the tool life and assure the reproducibility of the machined surface quality. After a summary of the metal cutting principles, we describe how the presence of a honed edge affects the performance of machining operation in different ways. We present the procedures followed to determine the cutting conditions adapted to our cutting tool and material during dry turning. The experimental procedure of machined samples and edge radius preparation methods used in this study are illustrated. Scanning Electronic Microscope, White Light Interferometry and Micro Indentation, were the employed techniques to understand the impact of honed insert edges in the surface integrity of the worked piece and to investigate tool life performances. Parameters such as: cutting efforts, wear types generated during life time tests, topographic and metallurgic surface were evaluated and allow to quantify the effect of the variation of the cutting edge radius “manufacturing spread” on the life time of the insert and the surface finish of the worked piece.

Crease-resistance is a very greatly desirable property in textile fibers. Of the natural fibers, wool exhibits this property to the greatest degree, followed by silk, cotton, and flax, which has a very low crease-resistance. The artificial cellulose fibers fall considerably below wool and silk in this respect. The improvement of the crease-resistance of rayon and other fibers has been sought in various after-treatment processes, in which substances are either deposited within the fiber, or react with it. There are numerous patents (22) for such methods of imparting crease-resistance. It would be highly desirable if the crease-resisting powers could be achieved "by a modification of the intrinsic properties of a fiber, that is, by producing a fiber which already is crease-resistant. The purpose of the work reported here was to attempt to produce a viscose rayon fiber with better crease-resisting properties, and to study the effect of a variation in the cellulose chain length distribution in the rayon upon this property. This work was done under a Fellowship of the Behr-Manning Corporation, Troy, New York. / Ph. D.