No description available.

No description available.

Thesis (Ph. D.)--University of Michigan, 1914. / Cover-title. "Reprinted from the Journal of the American leather chemists association December-November, 1915." Bibliography: p. 62. Also available in digital form on the Internet Archive Web site.

Thesis (Ph. D.)--University of Michigan, 1914. / Cover title. "Reprinted from the Journal of the American leather chemists association December-November, 1915." Bibliography: p. 62.

This thesis explores the effect of some parameters on the breaking strain, strength and the shape of the stress-strain curve of bovine leather as revealed by uniaxial tensile tests. The parameters explored are fatliquoring, moisture content, strain rate and cyclic stressing. A basic mechanical model of a simple two-dimensional weave is created and used to describe the effect of such a weave on the shape of the stress-strain curve. It is found that fatliquoring lubricates and opens up the fibre structure and thereby makes the weave more extensible. The increase in the extensibility depends on the direction in which samples are cut and therefore the manner in which the fibres are orientated. Patliquoring is observed to increase the degree to which fibres pull out at break. There are indications that the strength of fatliquored leather decreases with time of storage, while the extensibility increases. The effect of the strain rate on the breaking strain, the tensile strength and the shape of the stress-strain curve is not very clear. The stressing and releasing leather decreases the strength of leather when the fibres are orientated preferentially along the direction of the applied stresses, but has an insignificant effect in the transverse direction. It is concluded that the degree of lubrication in a weave and the orientation of the fibre bundles significantly influence the performance of leather in a test. Both moisture and fatliquoring lubricate the weave. In both the cases the degree of fibre adhesions in a weave is decreased. A well lubricated weave allows its constituent fibres to slide and align along the direction of the applied stresses, and this tends to occur before the fibres themselves areextended. Cyclic testing, at low strains, ruptures fibre adhesions and as a result induces permanent set and makes a hide softer. Most of the work done in breaking the fibre adhesion is done in the first cycle.

No description available.

No description available.

Leather production results in large volumes of waste water containing high levels of sodium sulphide, which has to be treated before disposal. The use of ozone to facilitate this oxidation was considered by first studying ozone-sodium sulphide reaction. The sodium sulphide solutions were found to be adequate models for the tannery effluent. The reaction order was found to be second order overall (first order in both sulphide and ozone). The true reaction order was found to be 0.33 for sulphide in the initial stages of the reaction. The use of ozone in conjunction with either UV radiation or a manganese catalyst was found to have no benefit to the rate of sulphide oxidation. The reaction products were thiosulphate, sulphite and sulphate. A mathematical model based on a first order consecutive reaction scheme was developed. The liquid phase mass transfer coefficient for physical absotption of ozone into water was estimated to be k'La=4.76 x 10-3 S-I, while the overall transfer coefficient during the ozone-sulphide reaction was estimated to be Kt.a=().0719 S-I. This gave an enhancement factor of 15.1 which indicates that ozone decomposition reactions may be negligable. It was estimated that a full scale ozone system would require the application of 120 kg of ozone per hour for 12 hours to treat 200 Itt waste water. An economic comparison of this proposed system indicates that operating costs for ozone would be approximately 6 times greater per m3 waste water than the costs for the current aeration treatment

No description available.

This thesis describes a successful attempt to automate a manual process in footwear industry. The process is called skiving of leather components and it is one of the early processes necessary for the assembly of shoe uppers. Skiving is the localised thinning of leather components, mainly at some of their edge regions. The purpose of skiving is to produce quality decorative edges or more importantly to enable attaching and joining components without forming thick, discomforting and weak joints. Although other processes in footwear manufacturing have been subject to partial or full automation, skiving has been performed for decades now with a standard mechanism that requires 3-dimensional manipulation of the components by a human operator. This research work was directed towards two main aims. One was to establish a novel method on the basis of which skiving may be performed without the need of human assistance. The developed method is called dynamic matrix skiving and it is capable of performing skiving on leather components by generating and actuating skive patterns as sets of finite elements of skived area to a given resolution. Following derivation and study of the method for skiving, the second phase was aimed at implementing a fully automatic skiving system. The main requirement from the system was to be an intelligent, component oriented, flow through, processing device. This required the capability to receive input components at any orientation and position along its transport mechanism, to recognise them as to their identity and relative position, and to perform skiving upon them without moving them or disturb their continuous flow throughout the entire operation. Individual chapters in this thesis describe the study and experimentation with regards to dynamic matrix skiving, and all logical steps taken to identify the necessary elements and implement their integration to produce the automated skiving system. The concluding part of this work includes presentation of the results obtained from the automated system, and it identifies the areas where further research and development is needed in order to improve the quality of its output.