Cellulose fiber was used to reinforce higher melting temperature engineering thermoplastics, such as nylon 6 and nylon 66. The continuous extrusion - direct compression molding processing and extrusion-injection molding were chosen to make cellulose fiber/nylon 6 or 66 composites. Tensile, flexural and Izod impact tests were used to demonstrate the mechanical properties of the composites. The continuous extrusion-compression molding processing can decrease the thermal degradation of cellulose fiber, but fiber doesn't disperse well with this procedure. Injection molding gave samples with better fiber dispersion and less void content, and thus gave better mechanical properties than compression molding. Low temperature compounding was used to extrude cellulose fiber/nylon composites. Plasticizer and a ceramic powder were used to decrease the processing temperature. Low temperature extrusion gave better mechanical properties than high temperature extrusion. The tensile modulus of nylon 6 composite with 30 % fiber can reach 5GPa; with a tensile strength of 68MPa; a flexural modulus of 4GPa, and a flexural strength of 100MPa. The tensile modulus of nylon 66 composites with 30 %fiber can reach 5GPa;with a flexural modulus of 5GPa; a tensile strength of 70MPa; and a flexural strength of 147MPa. The effect of thermal degradation on fiber properties was estimated. The Halpin-Tsai model and the Cox model were used to estimate the composite modulus. The Kelly-Tyson model was used to estimate the composite strength. The result indicates that the change of fiber properties determines the final properties of composites. Fiber length has a minor affect on both modulus and strength as long as the fiber length is above the critical length.

This work is mainly focused upon the preparation, processing and evaluation of mechanical and material properties of epoxy/single walled carbon nanotube (SWCNT) nanocomposite thin films. B-staged epoxy/SWCNT nanocomposite thin films at 50% of cure have been prepared for improving conductivity and mechanical performance of laminated composites. The SWCNTs were functionalized by oxidation and subsequent grafting using polyamidoamine generation 0 dendrimers (PAMAM-G0). The epoxy nanocomposites containing SWCNTs were successfully cast into thin films by manipulating degree of cure and viscosity of epoxy. The first section of this study focuses on the covalent oxidation and functionalization of single-walled carbon nanotubes (SWCNTs), which is necessary in order to obtain the full benefit of the SWCNTs inherent properties for reinforcement. In the second section of this work the preparation of B-staged epoxy/SWCNT nanocomposite thin films is discussed and what the purposes of thin films are. Additionally, the morphology as well as mechanical properties is evaluated by numerous means to obtain a clear picture as to the mechanisms of the epoxy/SWCNT nanocomposites. Furthermore, the effects of using sulfanilamide as a more attractive surface modifier for improved dispersion and adhesion and the effects of nylon particles for improved toughening on epoxy/SWCNT nanocomposites are discussed which displays improvements in numerous areas. Finally, based on these findings and previous studies, the B-staged epoxy/SWCNT nanocomposite thin films can be seamlessly integrated into laminated composite systems upon heating, and can serve as interleaves for improving conductivity and mechanical strengths of laminated fiber composite systems.

Plants containing condensed tannins (CT) represent an alternative feed resource for ruminants. However, limited information regarding nutrient disappearance from these plants is available. Two experiments were conducted to evaluate phosphorus (P) and other nutrient disappearance from plants containing CT. In the first experiment, nutrient disappearance from three native Texas species (Acacia angustissima var. hirta, Desmodium paniculatum, Smilax bona-nox, and Medicago sativa as control) were evaluated using the mobile nylon bag technique. For the second experiment, ruminal degradation parameters, ruminal and post-ruminal disappearance of P and other nutrients from a browse containing CT (Quercus virginiana) were compared to species without CT (Cynodon dactylon cv. Tifton 85, and Medicago sativa). Results from the first experiment indicate that the proportion of nutrient that disappeared during rumen, pepsin/HCl, or intestinal incubation differed among plant species and nutrient evaluated (P<0.05) and did not appear to be directly related to relative CT concentrations. Dry matter (DM), inorganic matter (IM), and organic matter (OM) disappearance were greater (P

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Thesis (MTech (Electrical Engineering))--Peninsula Technikon, 1996. / Word processed copy. Summary in English. Includes bibliographical references (leaves 81-82). Also available online.

Gloveboxes, where special nuclear material is handled and such as those present at Los Alamos National Labs, LANL, provide an experimental area confined within a protective shell and with strict environmental controls. These gloveboxes allow workers to indirectly interact with hazardous material. Unfortunately, these gloveboxes are not fail proof and are subject to occasional accidental failures resulting in possible breaches of containment and release of nuclear material. In particular, fires within the gloveboxes are of major concern with regard to the potential for breaches and damage to not only the glovebox but also to surrounding areas as well. Another, potentially even catastrophic, result of glovebox fires is the potential for the spread of radioactive contamination. There is some historical precedent of contaminant release resulting from glovebox fires, such as those at the Rocky Flats Plant (Buffer, 2012). Gloveboxes at LANL are currently equipped with manually activated fire suppression systems. In the event of an incident, a worker would hit a nearby emergency button and the system would be activated. However, this method relies on the worker to have the presence of mind in the face of danger to activate the system, and as such there is no true guarantee that the systems will be triggered. Since the level of consequence is dire, then the ideal situation requires that other fire suppression systems be present which do not rely on human interaction to function. The Fire Foe™ system has been chosen as a secondary failsafe measure in order to meet this need. Analysis of how the casing of the Fire Foe™ system, composed of nylon 6,6 polymer, weathers under irradiation in gloveboxes is paramount in determining the effectiveness and potential lifetimes of the systems within the gloveboxes. Samples of nylon 6,6 were exposed to a 5 Ci PuBe neutron source located at the University of Texas as well as a high dose rate beam of 4.5 MeV alpha particles located at Los Alamos to determine the effect of neutron and alpha particle damage on the polymer material. Subsequent mechanical testing was conducted to determine alteration to the tensile properties of the nylon 6,6 material for both irradiated and non-irradiated samples. / text

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