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Conducted under USDA Agreement No. 58-3159-7-11 Guayule Natural Rubber Program / Introduction: The United States imports 100 percent of its natural rubber. Ninety-two percent of our natural rubber production is concentrated in Southeast Asia, which is subject to interruptions through political action or direct military intervention. Natural rubber, a critical and strategic material, is necessary in such articles as aircraft and ground vehicle tires, medical supplies, resilient mounts, and certain acoustical applications. Synthetic elastomers cannot meet performance requirements in these areas. A domestic source of natural rubber will assist in assuring a supply of this critical material for industry and defense. The U.S. Department of Defense (DoD) and the U.S. Department of Agriculture (USDA) signed a Master Memorandum of Understanding in 1982 that calls for cooperation with respect to food, agriculture, forestry, nutrition, and other research of mutual interest. With this MOU both agencies adopted a supplemental agreement in 1986 that initiated the Joint Guayule Domestic Rubber Program, whose ultimate goal is to promote an economically viable domestic guayule rubber industry. To accomplish this goal, both agencies have provided funding to plant and cultivate guayule shrubs, construct a 150 -long- ton -per -year prototype plant to extract rubber from the shrubs, and conduct evaluations to establish the performance capability of military products fabricated with domestic guayule rubber. A critical component of the supplemental agreement calls for the USDA to assess the feasibility of a commercial guayule rubber processing facility of 50,000-long-ton-per-year nameplace capacity. This report, based on the best available data (1990) and on assumptions of future advancements in technology (for 1996), is designed to address the commercial prospects for the establishment of a domestic guayule rubber industry. It also examines the feasibility and factors involved in meeting either 20 percent or 100 percent of the natural rubber needs of the U.S. Department of Defense in both peacetime and national emergency conditions.

Isobutylene-rich elastomers bearing functional groups that engage N-arylmaleimides in C-H bond addition and/or alternating copolymerization are described. While inactive to cross-linking when treated at high temperature with peroxide alone, these co-curing elastomers can be cross-linked substantially when combined with bis-maleimide coagents such as N,N’-m-phenylene dimaleimide (BMI). Poly(isobutylene-co-isoprene) (IIR) samples containing relatively high amounts of residual isoprene unsaturation are shown to provide relatively low coagent cure reactivity, whereas IIR derivatives bearing pendant polyether or vinyl ether functionality are shown to provide exceptional cross-linking rates and extents when treated with identical BMI formulations. The design of such co-curing elastomers is discussed, along with the physical properties of the resulting vulcanizates. Isobutylene rich elastomers bearing oligomerizable (C=C) functional groups, macromonomers, that are activated in the presence of free-radical initiators are described. The criteria for determining the macromonomers that are best suited for preparing thermosets of IIR is discussed. While IIR derivatives bearing pendant acrylic, styrenic and maleimide functionality are shown to provide exceptional cross-linking rates and extents, they are also shown to suffer from instability in the absence of peroxide. IIR carrying pendant methacrylic and itaconate functionality are shown to provide a good balance of cure rates and stability. Nitroxyl based radical trap that provides scorch protection to the macromonomers while regenerating the cure extent is discussed. Functional macromonomer derivatives of IIR bearing containing multi-functional pendant groups are discussed. IIR derivatives with itaconate and low amounts of BHT pendant groups is shown to act as bound anti-oxidant while IIR containing pendant fluoro groups are shown to have reduced surface energy. Ionic coagents are used to cross-link IIR containing itaconate pendant groups and their physical properties are discussed. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2012-07-06 11:20:56.915

The South African Labour Market still lacks significant numbers of workers in spheres of decision-making. As a result the employers have been severely criticised by the trade union movement for not adopting worker participation strategies. This study was initiated in response to the recognition of the importance of worker participation as a dynamic and complex concept that allows both employers and employees to effectively participation in decision-making. The argument raised in this study is that worker participation promotes the spirit of solidarity, co-operation, satisfaction, tolerance, and discipline. It is argued in this study that the involvement of workers in decision-making creates a platform for dialogue. When both workers and employers start to dialogue a proper platform for worker participation is created. The objective of this study was to evaluate perceptions of whether worker participation can indeed lead to an increase in productivity and economic growth in the broader context. The study was also aimed at unpacking the argument raised by scholars that where there is worker participation, workers will feel the sense of owning the company and as a result they will be more satisfied with their jobs. After interrogating these issues a conclusion is reached that worker participation is essential if the company is to facilitate job satisfaction. This is supported by the findings of the literature review and the fieldwork conducted. As per responses given by the workers and managers, the findings of the study reveal that when employers do not introduce worker participation, it leads to the feelings of disempowerment and marginalisation of the workers. Both employees and employers are of an ideal that for the company to be run effectively and efficiently, the employees need to be given a proper platform to express their views. This then supports the arguments raised in the literature review that workers participation creates a situation whereby the workers voice is heard in the workplace. Furthermore, the results of this study conducted among workers and managers in Dunlop also reveal that in a work environment where there is no worker participation the production process is adversely affected. However, an important point to note is that both parties must be willing to accept each other as partners in decision-making. / Thesis (M.A.)-University of Durban-Westville, 2002.

Thesis (Ph. D.)--Columbia University, 1944. / "First edition." Published also without thesis note. Vita. "Selected bibliography": p. 419-430.

Thesis (Ph. D.)--Columbia University, 1944. / "First edition." Published also without thesis note. Vita. "Selected bibliography": p. 419-430.

Thesis (M.S.)--University of Michigan, 1957.

Thesis (M.S.)--University of Akron, Dept. of Polymer Engineering, 2005. / "August, 2005." Title from electronic thesis title page (viewed 11/28/2005) Advisor, Lloyd Goettler; Faculty Reader, Avraam I. Isayev; Department Chair, Sadhan C. Jana; Dean of College, Frank N. Kelley; Dean of Graduate School, George R. Newkome. Includes bibliographical references.

Um dos grandes desafios na indústria da borracha atualmente é suprir o mercado de pneumáticos, que é muito exigente em relação à durabilidade, segurança e economia. Significativo avanço nas melhorias simultâneas da aderência em pista molhada e resistência ao rolamento foi alcançado empregando sílica modificada por organosilanos em substituição ao negro de fumo. O objetivo deste trabalho foi desenvolver um composto elastomérico para uma banda de rodagem de pneu de carga combinando redução da resistência ao rolamento e melhora da aderência no molhado. Oito compostos foram preparados: duas formulações com base de negro de fumo (variando as condições de processamento), cinco formulações com a substituição parcial do negro de fumo por sílica e silano como agente de acoplamento (variando as condições de processamento e o teor de silano) e uma formulação com a substituição total do negro de fumo pela sílica. Foram avaliadas as propriedades reométricas, físicas, químicas, mecânicas e dinâmico-mecânicas dos compostos. Os resultados foram comparados a uma formulação padrão típica de banda de rodagem de pneus de carga. Através da análise dinâmico mecânica, o resultado mais relevante foi obtido com a proporção de 15 phr de sílica e 3 phr de silano para um processamento em três etapas, que conseguiu reduzir em 10% a resistência ao rolamento e aumentou em 18,5% a aderência no molhado. O uso parcial da sílica reduziu o desgaste por abrasão, promovendo maior durabilidade do composto. A formulação contendo apenas negro de fumo e preparada em três etapas de processamento também apresentou bons resultados, demonstrando que o processamento pode levar a uma melhor dispersão da carga. Para os compostos com 1,5 phr de silano não foram obtidos resultados satisfatórios, mostrando que para estes sistemas a carga não interage suficientemente com o polímero, devido provavelmente ao baixo teor de agente de acoplamento. Os resultados levam a concluir que o uso da sílica, o processamento em mais de uma etapa, bem como a quantidade de silano, promoveram um aumento na interação polímero-carga, melhorando assim as propriedades desejadas. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-08-18T13:54:15Z No. of bitstreams: 1 Dissertacao Viviane DallAgnol Veiga.pdf: 2147027 bytes, checksum: a7f2db3fc8bde4fab8821b414e8bbc9a (MD5) / Made available in DSpace on 2015-08-18T13:54:15Z (GMT). No. of bitstreams: 1 Dissertacao Viviane DallAgnol Veiga.pdf: 2147027 bytes, checksum: a7f2db3fc8bde4fab8821b414e8bbc9a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / One of the major challenges in the rubber industry today is related to the relationship between durability, safety and economy for tire applications. Important progress on rolling resistence reduction with good wet grip was achieved replacing carbon black by silica-silane coupling agent system. The aim of this work was to develop an elastomeric compound for a truck tire tread combining the reduction of the rolling resistance and the improvement in the wet grip. Eight compounds were prepared: two formulations based on carbon black (varying the processing conditions), five formulations with the partial replacement of the carbon black by a silica-silane coupling agent system (varying the processing conditions and the silane content), and one formulation with the total replacement of the carbon black by silica. Rheometric, physical, chemical, mechanical, and dynamic-mechanical properties were evaluated. The results were compared to a standard formulation based on a typical formulation of truck tire treads. From dynamic mechanical analysis, the results showed that for the compound with 15 phr of silica, 3 phr of silane, and three processing steps, the rolling resistance decreased by 10% compared to the standard compound, and the wet grip increased by 18.5%. The partial use of silica reduced the abrasion loss, confirming the durability of the compound. The formulation with only carbon black and prepared in three processing steps also had good results, showing that more processing steps lead to a better dispersion of carbon black. The compounds with 1.5 phr of silane showed unsatisfactory results; the filler does not interact sufficiently with the polymer, probably because the low content of coupling agent. The results showed that the use of silica and the processing conditions, as well as the quantity of silane, were important to improve filler-polymer interaction and to promote a general improvement in the properties.

Um dos grandes desafios na indústria da borracha atualmente é suprir o mercado de pneumáticos, que é muito exigente em relação à durabilidade, segurança e economia. Significativo avanço nas melhorias simultâneas da aderência em pista molhada e resistência ao rolamento foi alcançado empregando sílica modificada por organosilanos em substituição ao negro de fumo. O objetivo deste trabalho foi desenvolver um composto elastomérico para uma banda de rodagem de pneu de carga combinando redução da resistência ao rolamento e melhora da aderência no molhado. Oito compostos foram preparados: duas formulações com base de negro de fumo (variando as condições de processamento), cinco formulações com a substituição parcial do negro de fumo por sílica e silano como agente de acoplamento (variando as condições de processamento e o teor de silano) e uma formulação com a substituição total do negro de fumo pela sílica. Foram avaliadas as propriedades reométricas, físicas, químicas, mecânicas e dinâmico-mecânicas dos compostos. Os resultados foram comparados a uma formulação padrão típica de banda de rodagem de pneus de carga. Através da análise dinâmico mecânica, o resultado mais relevante foi obtido com a proporção de 15 phr de sílica e 3 phr de silano para um processamento em três etapas, que conseguiu reduzir em 10% a resistência ao rolamento e aumentou em 18,5% a aderência no molhado. O uso parcial da sílica reduziu o desgaste por abrasão, promovendo maior durabilidade do composto. A formulação contendo apenas negro de fumo e preparada em três etapas de processamento também apresentou bons resultados, demonstrando que o processamento pode levar a uma melhor dispersão da carga. Para os compostos com 1,5 phr de silano não foram obtidos resultados satisfatórios, mostrando que para estes sistemas a carga não interage suficientemente com o polímero, devido provavelmente ao baixo teor de agente de acoplamento. Os resultados levam a concluir que o uso da sílica, o processamento em mais de uma etapa, bem como a quantidade de silano, promoveram um aumento na interação polímero-carga, melhorando assim as propriedades desejadas. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / One of the major challenges in the rubber industry today is related to the relationship between durability, safety and economy for tire applications. Important progress on rolling resistence reduction with good wet grip was achieved replacing carbon black by silica-silane coupling agent system. The aim of this work was to develop an elastomeric compound for a truck tire tread combining the reduction of the rolling resistance and the improvement in the wet grip. Eight compounds were prepared: two formulations based on carbon black (varying the processing conditions), five formulations with the partial replacement of the carbon black by a silica-silane coupling agent system (varying the processing conditions and the silane content), and one formulation with the total replacement of the carbon black by silica. Rheometric, physical, chemical, mechanical, and dynamic-mechanical properties were evaluated. The results were compared to a standard formulation based on a typical formulation of truck tire treads. From dynamic mechanical analysis, the results showed that for the compound with 15 phr of silica, 3 phr of silane, and three processing steps, the rolling resistance decreased by 10% compared to the standard compound, and the wet grip increased by 18.5%. The partial use of silica reduced the abrasion loss, confirming the durability of the compound. The formulation with only carbon black and prepared in three processing steps also had good results, showing that more processing steps lead to a better dispersion of carbon black. The compounds with 1.5 phr of silane showed unsatisfactory results; the filler does not interact sufficiently with the polymer, probably because the low content of coupling agent. The results showed that the use of silica and the processing conditions, as well as the quantity of silane, were important to improve filler-polymer interaction and to promote a general improvement in the properties.