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The University of Maine

Electronic Theses and Dissertations

Oxidation

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Kinetics And Mechanism Of Oxygen Delignification, Yun Ji May 2007

Kinetics And Mechanism Of Oxygen Delignification, Yun Ji

Electronic Theses and Dissertations

Considerable research has been conducted into the kinetics and selectivity of the oxygen delignification process to overcome limitation in its use. However most studies were performed in a batch reactor whereby the hydroxide and dissolved oxygen concentrations are changing during the reaction time in an effort to simulate tower performance in pulp mills. This makes it difficult to determine the reaction order of the different reactants in the rate expressions. Also the lignin content and cellulose degradation of the pulp are only established at the end of the experiment when the sample is removed from the batch reactor. To overcome …


High Temperature Compression Testing Of An Advanced Carbon-Carbon Composite In An Oxidizing Atmosphere, Joshua C. Walls Jan 2002

High Temperature Compression Testing Of An Advanced Carbon-Carbon Composite In An Oxidizing Atmosphere, Joshua C. Walls

Electronic Theses and Dissertations

Compression testing of an advanced, three-dimensional weave, carbon-carbon composite was performed from room temperature to 2192°F (1200°C) in an oxidizing environment. The material tested is primarily used for missile nose cones and rocket nozzles. A test system and test method was developed for performing high temperature compression testing and techniques were developed for machining the material to minimize fiber damage and maintain accurate tolerances. Test specimens were cut from a block of the test material in the three principal fiber orientations, and off-axis tests were cut at 45" orientations to each principal fiber direction. The specimens were tested by direct …