Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. In two parts. Includes bibliographical references (leaves 602-609).

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Guayule (Parthenium argentatum Gray) is a rubber producing plant native to the Chihuahuan Desert, which is currently being investigated as a source of hypoallergenic latex. Current efforts are focusing on increasing latex/rubber production in the plant by either manipulating the rubber biosynthetic pathway, altering agronomic practices to take advantage of environmental conditions that increase rubber synthesis, or both. Field and greenhouse studies were conducted to more fully understand the effect of genetic and environmental manipulation on rubber production in guayule. Three guayule breeding lines were transformed in order to increase the availability of the initiators of rubber synthesis. The tissue-culture-derived transgenic plants and their seed-generated progeny were grown in separate field experiments. Transformation with the genes for the initiators of rubber synthesis did not increase rubber concentration or yield. Height and width had high heritability estimates in the transgenic progeny and were the traits most correlated with rubber yield, while rubber concentration was poorly correlated with height and width. Greenhouse studies were conducted to understand why water stress and low night temperatures increase rubber concentration. Water stress increased the contribution of the stems to the total rubber in the plant and increased the bark to wood ratio of the stem. Most rubber is accumulated in the stems and these two effects of water stress contributed to the increased rubber concentration in water-stressed plants. Low night temperature reduced plant growth without a decrease in carbon exchange. Allocation of carbon fixation products to rubber synthesis rather than growth, contribute to the high rubber production under low night temperatures. Contributions from both breeders and agronomists are needed to further improve guayule rubber/latex yield.

The two interconnected rubber balloons system is a demonstration widely used to show the effect of surface tension; however, the nature of the rubber skin, sizes of the balloons limit the ability of this demonstration. In this research, I measured the circumference and pressure of balloons for the calculation of surface tension. It was found that the demonstration can be done between circumferences of 30 cm to 50 cm for the party balloons to show the effect of surface tension as explained by the Laplace-Young equation.

No description available.

Macromonomers bearing oligomerizable C=C functionality have been prepared by the nucleophilic displacement of allylic bromide functionality on brominated poly(isobutylene-co-isoprene) (BIIR). Whereas commercial grades of isobutylene-rich elastomers do not cure under the action of peroxides, these materials undergo simultaneous cross-linking and degradation when activated by radical initiators, with the competitive balance dictated by the reactivity of the oligomerizable group. Vinyl benzoate, vinyl imidazolium, and acrylate functionalities cure rapidly to high cross-link density whereas the maleimide graft is too reactive and unstable for any utility. Methacrylate and itaconate macromonomers cure to moderate extent while maleate esters and unactivated terminally unsaturated groups are unable to significantly counteract the degradation mechanism and do not afford any appreciable cross-link density to BIIR. The most reactive macromonomers display the potential for scorch, an effect that is efficiently mitigated with the introduction of (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) to quench free radical cure activity. Furthermore, an acrylated adduct, AOTEMPO, is able to recover more of the cross-link density that would otherwise be lost to irreversible free radical coupling. These nitroxyls display longer than expected induction times, likely due to the catalytic nature of TEMPO when alkoxyamine decomposition is significant. A suite of elastomeric ionomers bearing N-functional imidazolium bromide functionality have been prepared in order to investigate the N-alkylation dynamics with brominated poly(isobutylene-co-para-methylstyrene) (BIMS) as well as the subsequent peroxide cure activity of the reactive ionomer. A functional imidazole bearing a methacrylate group displayed moderate alkylation rate and good cure activity whereas a 4-vinylbenzyl analogue provides fast alkylation at the expense of storage stability. N-Allylimidazole is rapidly alkylated by BIMS in both solution and solvent free processes and the resulting ionomer displays unique cure dynamics. This phenomenon is investigated by model compound polymerization and is likely due to the unique free radical reactivity of allyl imidazolium moieties. The cross-linked ionomer displays many of the beneficial physical properties associated with a hybrid ionic/covalent network including good resistance to stress relaxation and thermal stability. / Thesis (Master, Chemical Engineering) -- Queen's University, 2014-01-29 17:09:42.428

No description available.

Thesis (Ph. D. - Plant Sciences)--University of Arizona, 1984. / Includes bibliographical references (leaves 75-77).

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xiii, 101 p. : ill. (some col.). Includes two zip files of TIF images. Includes abstract. Includes bibliographical references (p. 93-94).

Thesis (M.Sc. (Physical Chemistry))--Mahidol University, 1982.