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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

The Simulation of Random Load Fatigue Damage by Block Load Programmes

Power, E. M. January 1975 (has links)
No description available.
122

Crystallochemical engineering of calcium sulphate

Farrall, Denise Jane January 2004 (has links)
The specific crystallographic form of inorganic crystalline materials not only determines the physical and chemical properties of the individual crystals but can also affect the bulk properties of a material. One such bulk material that is comprised of a crystal matrix is plasterboard. Inthis material, individual calcium sulphate dihydrate (CSD) crystals are interlocked to form a coherent structure. It has been shown that by adding certain chemical molecules to the standard formulation, that macro-scale properties can be altered. In this thesis, the option to modify the crystal interactions by tailoring the habit and morphology of this mineral was investigated. In the control system, the nucleation and growth of this mineral was observed to be a staged process. Firstly, monocrystals ofCSD expressing (010) > {120}>{111} faces were harvested. At a relatively high supersaturation, (100) contact twins were formed, and the twinning process effected the stabilisation of a new cohort of faces; {II O} which replaced the {120} forms. As the supersaturation fell over a time period (24 hours), the mode of twinning altered; contact twin variants were observed, and the incidence of penetration twinning facilitated by heterogeneous nucleation was significant. Three different types of additives were investigated to see what effect they might have on CSD crystallisation; these being; (i) low molecular weight carboxylic acids, (ii) low molecular weight phosphates and phosphonates and (iii) molecules that contain hydroxyl groups. Low molecular weight carboxylic acid, phosphate and phosphonate additives were found to affect the twinning process of CSD in a concentration dependent manner. At additive loadings the contact twinning seen in the control system was inhibited whereas higher additive concentrations inhibited penetration twinning; observations which suggest that the processes mediating the two types of twinning were subtly different. Additive-specific changes in the morphology of the crystals were also noted suggesting that molecular recognition is a key issue in the habit modification of this mineral. Of particular interest however was the continued dominance of the water stabilised (010) and {120} faces under all conditions which raises some interesting questions about the competing effects of hydrogen bonding and cation-mediated additive docking as processes directing additive interactions with crystal surfaces. In the case of the polyhydroxyl additives, contact twinning was also inhibited but penetration twinning persisted even when the additive was in excess (relative to the calcium concentration). As polyhydroxyls have low calcium stability constants, this suggests that the ability of these molecules to inhibit penetration twinning of CSD is related to their calcium binding affinity which will affect both super saturation and adsorption phenomena.
123

The nucleation and growth of crystals from solution - molecular self assembly, materials science and process technology

Davey, Roger J. January 2010 (has links)
No description available.
124

Application of fracture mechanics to the impact behaviour of polymers

Plati, Evangelina January 1975 (has links)
No description available.
125

The flow properties of foams

Starkey, Philip Earle January 1976 (has links)
No description available.
126

Thickness, temperature and environmental effects in the fracture of polymers

Parvin, Mohammad January 1975 (has links)
No description available.
127

The fabrication and properties of steel fibre reinforced cements

Salih, Mohammed Abdel Aziz January 1978 (has links)
No description available.
128

The bonding of resins to dental tissues

Cranfield, Peter John January 1978 (has links)
No description available.
129

The environmental stress cracking of polyethylenes : a fracture mechanics approach

Linkins, Nicholas Henshall January 1975 (has links)
No description available.
130

Environmental fatigue of polymers : a fracture mechanics approach

El-Hakeem, Hany Mohamed Abd January 1975 (has links)
No description available.

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