Companies providing products have many requirements, both from standards and customers, that they need to comply with in order to be able to sell their product. Veoneer AB is a leading automotive machine vision supplier, providing mono, stereo, night vision and driver monitoring systems consisting of both electronic, mechanical and optical components. These systems have to withstand certain environmental tests in order to assure the lifetime of the totalsystems. Since the life time is usually several years accelerated tests are used that correspond to a few weeks ormonths. The tests used at Veoneer are specified for electronic equipment and what Veoneer does not know today is ifthe accelerated environmental tests stated for electronic equipment are relevant for the optical component of the visionsystem. In this master thesis project two different accelerated environmental tests, dry and damp heat, have been chosen inorder to investigate the effect of temperature and relative humidity on the adhesive in the optical component connecting the sensor and lens. The optical components where characterized by measurement of focus position and mechanicalstrength. Different combinations of temperature and relative humidity where chosen in order to compare the effect of different stress levels but also for the purpose of deriving parameters needed for accelerated testing models such as theArrhenius, Eyring, Lawson and Peck model. Amongst the results from this thesis work is the focus shift measurement which follows the same trend as seen in previous research regarding the effect of temperature and relative humidity on adhesives. With an exponentialdistribution being seen in different directions for the respective stresses. Pull tests show a greater degradation withhigher stress levels, where one test case shows the greatest degradation. Calculations regarding activation energy and constants for models match previous research where one model, combining temperature and relative humidity, showssimilar values as found in literature. Calculations also show that standard accelerated life time tests overexpose adhesives due to calculations of test times with lower activation energies.

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Made available in DSpace on 2014-06-11T19:35:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-09-02Bitstream added on 2014-06-13T19:46:24Z : No. of bitstreams: 1 nogueira_dc_dr_ilha.pdf: 465474 bytes, checksum: 73aaf83a41766ac828cf08b26abed5fe (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O uso de sementes com alto nível de vigor é fundamental para o sucesso de um empreendimento agrícola, pois apresentam melhor desempenho em campo, resultando em maior produção. O objetivo do trabalho foi verificar o nível do vigor em sementes de três híbridos de milho submetidas ao envelhecimento acelerado e seus desempenhos em laboratório e em campo. Para tanto sementes dos híbridos AG-5020, AG-8088 e BG-7049 foram envelhecidas artificialmente à 41oC por 0, 48 e 72 horas e secadas em estufa à 38 °C/48 horas para a formação dos diferentes lotes. Experimento 1 – No laboratório, verificou-se o nível de vigor e o desempenho das sementes dos diferentes lotes por meio de análises de germinação, primeira contagem, deterioração controlada, tetrazólio, comprimento de raiz primária e mesocótilo, número de raízes/plântula, massa de matéria seca de plântula e emergência em solo. Experimento 2 – No campo as sementes foram semeadas manualmente em parcelas de 8 linhas de 5m, espaçamento de 0,5m e densidade de 80.000 plantas ha-1. Verificou-se o nível de vigor e o desempenho das plantas em campo pelas avaliações de características morfológicas das plantas, caracteres da espiga e componentes de produtividade. O delineamento experimental foi o inteiramente casualizado com os tratamentos obtidos da combinação 3 x 3 (híbridos x níveis de vigor) com quatro repetições. Em laboratório as sementes mais vigorosas apresentaram melhores desempenhos e em campo proporcionaram a obtenção de maior produtividade, o que se deve principalmente ao maior estande final obtido. As características das plantas e das espigas estão relacionadas ao genótipo de cada híbrido não se verificando efeito do vigor das sementes / The use of seeds with high level of vigor is fundamental to the success of an agricultural development, since its have better performance in the field, resulting in increased production. The objective of this study was to assess the level of vigor in seeds of three maize hybrids submitted to accelerated aging and their performance in laboratory and field. Seeds of AG-5020, AG-8088 and BG-7049 were artificially aged at 41°C for 0, 48 and 72 hours and dried in an stove at 38 °C /48 hours for the formation of the different lots. Experiment 1 – in the laboratory, we found the level of vigor and the performance of different seed lots by means of analysis of germination, first count, controlled deterioration, tetrazolium, length of primary root and mesocotyl, number of roots/seedling, seedling mass dry matter and seedling emergence in soil. Experiment -2 the seeds were manually sown in plots of 8 rows of 5m, 0,5 m spacing and density of 80000 plants ha-1. The level of vigor and performance of plants in the field evaluations of morphological characteristics of plants, components and characters of the spike in productivity. The experimental design was completely randomized treatments obtained with the combination 3 x 3 (hybrid x vigor levels) with four replications. In the laboratory the most vigorous seeds showed better performances and the field higher productivity, which is mainly due to higher final stand. As characteristics of plants and spike are related to the genotype of each hybrid was not observed effect of vigor seeds

abstract: The aging mechanism in devices is prone to uncertainties due to dynamic stress conditions. In AMS circuits these can lead to momentary fluctuations in circuit voltage that may be missed by a compact model and hence cause unpredictable failure. Firstly, multiple aging effects in the devices may have underlying correlations. The generation of new traps during TDDB may significantly accelerate BTI, since these traps are close to the dielectric-Si interface in scaled technology. Secondly, the prevalent reliability analysis lacks a direct validation of the lifetime of devices and circuits. The aging mechanism of BTI causes gradual degradation of the device leading to threshold voltage shift and increasing the failure rate. In the 28nm HKMG technology, contribution of BTI to NMOS degradation has become significant at high temperature as compared to Channel Hot Carrier (CHC). This requires revising the End of Lifetime (EOL) calculation based on contribution from induvial aging effects especially in feedback loops. Conventionally, aging in devices is extrapolated from a short-term measurement, but this practice results in unreliable prediction of EOL caused by variability in initial parameters and stress conditions. To mitigate the extrapolation issues and improve predictability, this work aims at providing a new approach to test the device to EOL in a fast and controllable manner. The contributions of this thesis include: (1) based on stochastic trapping/de-trapping mechanism, new compact BTI models are developed and verified with 14nm FinFET and 28nm HKMG data. Moreover, these models are implemented into circuit simulation, illustrating a significant increase in failure rate due to accelerated BTI, (2) developing a model to predict accelerated aging under special conditions like feedback loops and stacked inverters, (3) introducing a feedback loop based test methodology called Adaptive Accelerated Aging (AAA) that can generate accurate aging data till EOL, (4) presenting simulation and experimental data for the models and providing test setup for multiple stress conditions, including those for achieving EOL in 1 hour device as well as ring oscillator (RO) circuit for validation of the proposed methodology, and (5) scaling these models for finding a guard band for VLSI design circuits that can provide realistic aging impact. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2017

Orientador: Rinaldo César de Paula / Banca: Nelson Moreira Carvalho / Banca: Sonia Cristina Juliano Gualtieri de Andrade Perez / Resumo: Poecilanthe parviflora é uma planta arbórea com potencial para uso em áreas degradadas e no paisagismo. Este trabalho teve por objetivo caracterizar biometricamente as sementes, descrever e ilustrar os aspectos morfológicos de sementes e plântulas, avaliar condições de temperatura para condução do teste de germinação e adaptar metodologia para condução dos testes de tetrazólio, condutividade elétrica e envelhecimento acelerado. O teste de germinação foi conduzido sob temperaturas constantes (10, 15, 20, 25, 30, 35 e 40ºC) e sob temperaturas alternadas (20-30, 25-35 e 20-35ºC), utilizando quatro repetições de 25 sementes por tratamento. Para o teste de de tetrazólio, as sementes foram condicionadas durante 42 horas a 25ºC e, após a retirada do tegumento, imersas em soluções de diferentes concentrações de tetrazólio (0,05, 0,075 e 0,1%) a 35ºC, por uma, duas e três horas, em duas repetições de 10 sementes. A condutividade elétrica foi avaliada em diferentes períodos de embebição (24, 48, 72, 96 e 120 horas) a 25ºC, utilizando quatro repetições de 10 sementes. As sementes foram envelhecidas durante 72 horas a 42ºC, utilizando-se quatro repetições de 20 sementes. O delineamento estatístico utilizado foi o inteiramente casualizado e as médias foram comparadas pelo teste de Scott-Knott a 5% de probabilidade. A semente é exalbuminosa e a emergencia de plântula, hipógea. Concluiu-se que o teste de germinação pode ser conduzido a 25 e a 25-35ºC; a solução de tetrazólio foi eficiente a 0,1%, por duas horas; o teste da condutividade elétrica foi eficiente na diferenciação dos lotes nos períodos de 96 e 120 horas de embebição das sementes a 25ºC; o envelhecimento acelerado foi mais eficiente que o teste de germinação, na diferenciação dos lotes. / Abstract: Poecilanthe parviflora is a tree with a good potential for revegetation and ornamental purposes. The objectives of this research were: evaluate biometrical characteristics of the seed and seedling, determine the best temperatures for the germination test, and determine the best conditions for the tetrazolium, electrical conductivity and accelerated aging tests. Four replicates of 25 seeds each and constant temperatures of 10, 15, 20, 25, 30, 35, and 40ºC and alternate temperatures of 20-30, 25-35, and 20-35ºC were used for germination test. For the tetrazolium test, the seeds were submitted to a pre-imbibition during 42 hours at 25ºC and then had their tegument removed before immersing two replicates of 10 seeds each in the tetrazolium solution. The tetrazolium solution concentrations were of 0.05, 0.075, and 0.1%. At a temperature of 35ºC, the seeds remained in the tetrazolium solution for 1, 2, and 3 hours. Electrical conductivity was carried out after the seeds (four replicates of 10 seeds each) had remained imbibiting water for 24, 48, 72, 96, and 120 hours at a temperature of 25ºC. The accelerated aging test was conducted submitting four replicates of 20 seeds each to conditions of 42ºC for a period of 72 hours. The seed is an exalbuminous and its germination of the hypogeal type. Either a constant temperature of 25ºC or alternate temperatures of 25-35ºC were found to be the ideal ones for the germination test. The best tetrazolium results were found when the seeds were immersed in a 0.1% tetrazolium solution for 2 hours. The best electrical conductivity results were obtained when the seeds remained imbibing water for either 96 or 120 hours. The accelerated aging test showed a efficiency in separating seed lots higher than that of the germination test. / Mestre

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-02-26T12:56:08Z No. of bitstreams: 1 PGPV16MA194.pdf: 1071160 bytes, checksum: 532abfafc565e7d83c257ec9a501bd35 (MD5) / Made available in DSpace on 2018-02-26T12:56:08Z (GMT). No. of bitstreams: 1 PGPV16MA194.pdf: 1071160 bytes, checksum: 532abfafc565e7d83c257ec9a501bd35 (MD5) Previous issue date: 2016-09-08 / FAPESC / The success in the establishment, production and storage of seeds depends on the physiological quality. The objective was evaluate the physiological quality and red clover seed yield of cultivars and Quiniquelli and Estanzuela 116, sown in two locations in the mountainous region of Santa Catarina State in 2014/2015 and 2015/2016 seasons. The seeds of the crop 2014/2015 were compared with seeds from Rio Grande do Sul crop harvested in the 2013/2014 and 2015/2016 crop seeds were compared with seeds harvested in the 2014/2015 crop. To assess the viability of the seeds was carried out the germination test (20°C, 10 days in germination chamber). The physiological quality was estimate by the accelerated aging test with saline (42°C, 48 h aging chamber) and seedling length (measured in cm with universal caliper). Productivity was established by harvest all mature inflorescences of the floor area of 3 m2 per repetition, 4 replicates per cultivar and the result was expressed in kg.ha. Regarding the effect the accelerated aging test, there was a reduction of 78% to 116 Estanzuela cultivate the environment 2. The productivity of seeds was higher for cultivar Estanzuela 116 independent environmental and crop, highlighting yet this cultivar in the first crop environment 1 with 304.84 kg / ha. The cultivar Estanzuela 116 was more promising for serrana region of Santa Catarina State / O sucesso no estabelecimento da pastagem, assim como a produção e armazenamento das sementes depende da qualidade fisiológica destas. O objetivo do trabalho foi verificar a qualidade fisiológica e a produtividade de sementes de trevo-vermelho das cultivares Quiniquelli e Estanzuela 116, semeadas a campo em dois ambientes (1 e 2) da região serrana de Santa Catarina nas safras 2014/2015 e 2015/2016. As sementes da safra 2014/2015 foram semeadas em épocas diferentes (19/05/2014 e 12/06/2014) e foram comparadas com sementes provenientes do Rio Grande do Sul colhidas da safra 2013/2014 e as sementes da safra 2015/2016 foram semeadas em uma única época (18/05/2015) e foram comparadas com as sementes colhidas na safra 2014/2015. Para avaliar a germinação colocou-se as sementes em câmara de germinação a 20°C por um período de 10 dias. A determinação do vigor foi estimada através do teste de envelhecimento acelerado com solução salina (42°C; 48 h em câmara de envelhecimento) e comprimento de plântulas (medidas em cm com paquímetro universal). A produtividade foi estabelecida pela colheita de todas as inflorescências maduras da área útil de 3 m2 por repetição, sendo 4 repetições por cultivar e o resultado foi expresso em kg ha-1. Com relação ao vigor pelo teste de envelhecimento acelerado, observou-se redução para a cultivar Estanzuela 116 no ambiente 2. A produtividade das sementes foi maior para a cultivar Estanzuela 116 independente do ambiente e da safra, destacando-se ainda esta cultivar no ambiente 1 da primeira safra, com 304,84 kg/ha. A cultivar Estanzuela 116, para produção de sementes, mostrou-se mais promissora para a região Serrana de Santa Catarina

Made available in DSpace on 2015-03-26T13:40:06Z (GMT). No. of bitstreams: 1 texto completo.pdf: 200867 bytes, checksum: f04eb43a13fa036d663e50de96720b1d (MD5) Previous issue date: 2007-07-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective was to evaluate the vigor of corn seeds treated with homeopathic solutions. The experiments were done at the Laboratory of Soybean Breeding DFT/UFV. The homeopathic medicines were prepared at the Laboratory of Homeopathy of DFT/UFV in distilled water and applied in the "double-blind" procedure. Sixteen gerbox containing 40 mL of water with 100 seeds of corn, cultivar UFVM 100 Nativo, were covered with germitest paper. They were placed in B.O.D and submitted to the accelerated aging at 42ºC for 96 hours in the darkness. Normal seeds and aged seeds were divided in 4 replications of 50 seeds, weighted and soaked in solution containing 75 mL of distilled water, plus 2 mL of the homeopathic medicine for 24 hours. After completing 24 hours of soak the electrical conductivity of the solution was determined. The seeds were weighted and calculated the mass earnings of the seeds, which were distributed in rolls of germitest paper and placed in germination chamber at 25ºC. The analyses were done in 4th and 7th day after test beginning and the data were submitted to variance analysis and mean test. First trial: Antimonium crudum applied in the dinamizations 10CH to 15CH in normal corn seeds and aged seeds and distilled water as a control. Normal plantlets, length of the primary root, length of the aerial part and total length of the seedlings were determined. Aged seeds treated with 10CH to 15CH generated more normal plantlets than the control. Aged seeds treated with respectively 11CH and 14CH gave rise to larger and smaller growth of the primaryn root. Normal seeds treated with 14CH generated seedlings with smaller growth and total length. Second trial: the response of corn seeds was evaluated after aging and treatment with Arsenicum album 10CH to 15CH and the controls aged seed and normal seed, both treated with distilled water. Electrical conductivity, mass of the seed after aging, mass of the seed after 24 hours of soak, mass earnings, mass of the fresh seedlings, mass of dried aerial part, mass of the dried plantlets were determined. There was no significant difference among the variables when compared to control 1 (aged seed). All treatments from 10CH to 15CH caused decrease in leaching and mass earning of the seeds compared to control 2. The treatments 10CH, 11CH, 13CH and 15CH gave rise to lowest mass of fresh plantlets, however all treatments caused reduction in the mass of dried plantlets. The treatments 10CH, 11CH, 12CH, 13CH and 15CH caused mass decrease of dried aerial part. / Este trabalho teve como objetivo avaliar o vigor de sementes de milho tratadas com preparados homeopáticos. Os experimentos foram conduzidos no Laboratório de Melhoramento de Soja DFT/UFV. Os preparados homeopáticos foram elaborados no Laboratório de Homeopatia do DFT/UFV, dinamizados em água destilada e aplicados no procedimento duplo-cego . Distribuíram-se 100 sementes de milho, cultivar UFVM 100 Nativo, sobre telas de alumínio acondicionadas no interior de caixas gerbox adaptadas ao teste de envelhecimento acelerado que mantém suspensa as telas. Para garantir umidade relativa do ar próxima a 100%, foram colocados 40 mL de água no fundo das caixas e tampadas, em seguida colocadas em B.O.D e submetida ao envelhecimento acelerado, a 42ºC por 96 horas no escuro. Após o envelhecimento acelerado as sementes envelhecidas foram divididas em quatro repetições com 50 sementes, pesadas em balança com sensibilidade de 0,001g e imersas em solução contendo 75 mL de água destilada mais 2 mL do preparado homeopático por 24 horas. Após este período foi determinada a condutividade elétrica da solução. As sementes foram pesadas e calculado o ganho de massa. Em seguida as sementes foram distribuídas em rolos de papel germitest e colocadas em germinador a 25ºC. As avaliações foram feitas no 4º e 7º após início do teste e os dados foram submetidos à análise de variância e teste de média. No primeiro ensaio foi aplicado o preparado homeopático Antimonium crudum nas dinamizações 10CH a 15CH, em sementes de milho não envelhecidas e submetidas ao envelhecimento acelerado, tendo como testemunha água destilada. As características avaliadas foram: plântulas normais, comprimento da raiz primária, comprimento da parte aérea e comprimento total da plântula. Sementes envelhecidas tratadas com as dinamizações 10CH a 15CH desenvolveram mais plântulas normais do que o controle. Sementes envelhecidas tratadas com as dinamizações respectivamente 11CH e 14CH causaram maior e menor crescimento da raiz primária. Sementes não envelhecidas tratadas com 14CH geraram plântulas com menor crescimento da parte aérea e comprimento total. No segundo ensaio foi avaliada a resposta de sementes de milho submetidas ao envelhecimento acelerado tratadas com o preparado homeopático Arsenicum album nas dinamizações de 10CH a 15CH e dois controles: sementes envelhecidas e semente não envelhecida, tratadas com água destilada. Não houve diferença significativa entre as variáveis quando em comparação com a semente envelhecida (controle 1). Todas as dinamizações de 10CH a 15CH causaram diminuição na perda de lixiviados e ganho de massa das sementes em comparação com as sementes não envelhecidas (controle 2). Nas dinamizações 10CH, 11CH, 13CH e 15CH houve menor massa da plântula fresca, entretanto as dinamizações 12CH e 14CH reverteram o efeito do processo de envelhecimento aumentando a massa da plântula fresca como efeito homeostático nas sementes envelhecidas. As dinamizações 10CH, 11CH, 12CH, 13CH e 15CH causaram diminuição da massa da parte aérea seca, a dinamização 14CH reverteu os efeitos do envelhecimento acelerado aumentando a massa da parte aérea. Todas as dinamizações causaram menor massa da plântula seca quando comparada com a semente não envelhecida (controle 2).

A proposta desse estudo foi avaliar in vitro a alteração de cor e a rugosidade superficial de três marcas de resinas indiretas de nova geração, após serem submetidas ao processo de envelhecimento artificial acelerado. Foram confeccionados 12 corpos-de-prova (15 mm diâmetro e 2 mm espessura) para as resinas: Artglass (Heraeus Kulzer), Solidex (Shofu), Targis (Ivoclar Vivadent) que receberam acabamento e polimento com discos Sof-Lex - 3M. As primeiras mensurações para o teste de rugosidade e de espectrofotometria colorimétrica foram realizadas, respectivamente, com Rugosímetro Surfcorder SE 1700 (Kosakalab) e Espectrofotômetro PCB 6807 (BYK GARDNER), que utiliza a escala CIE L*a*b* para determinação da cor. As amostras foram submetidas ao processo de envelhecimento artificial acelerado por 384 horas, e após esse período foram novamente submetidas ao processo de leitura de cor e de rugosidade. A estabilidade de cor foi determinada pela diferença (&#916;E) entre coordenadas L*, a* e b* obtidas das amostras antes e após o envelhecimento. Os resultados foram submetidos à ANOVA (Tukey) e mostraram que todas as resinas apresentaram alterações de cor, sem significância estatística (p>0,05). A resina Solidex foi a que apresentou maior valor de alteração de cor (&#916;E = 4,31), e que apresentou um padrão de rugosidade (Ra= 0,079) estatisticamente diferente das resinas Art-Glass (Ra=0,141) e Targis (Ra=0,124) (p<0,001). Conclusão: Todas as resinas apresentaram alteração de cor e aumento de rugosidade após o envelhecimento artificial acelerado. A resina Solidex apresentou a maior alteração de cor e a menor rugosidade após o envelhecimento acelerado. / This study had the aim of assessing in vitro color change and surface roughness of three brands of new generation indirect resins, after being submitted to accelerated aging process. Twelve specimens were constructed (15 mm diameter and 2 mm width) for the resins: Artglass (Heraeus Kulzer), Solidex (Shofu), Targis (Ivoclar Vivadent) which were finished and polished with the disks Sof-Lex - 3M. The first measurements for the roughness and spectrophotometer colorimeter tests were performed, respectively, with the Surfcorder Profilometer SE 1700 (Kosakalab) and Spectrophotometer PCB 6807 (BYK GARDNER), which uses the scale CIE L*a*b* for color determination. The samples were submitted to the accelerated artificial aging process for 384 hours, and then submitted once again to the process of color and roughness reading. Color stability was determined by the difference (&#916;E) between coordinates L*, a*, and b* obtained from the samples before and after aging. The results were submitted to ANOVA (Tukey) and showed that all resins presented color changes with no statistical significance (p>0.05). Solidex resin showed the highest value of color change (&#916;E = 4.31), and a roughness pattern (Ra= 0.079) statistically different from the resins Art-Glass (Ra=0.141) and Targis (Ra=0.124) (p<0,001). Conclusion: All resins showed color change and an increase of roughness after artificial accelerated aging. Solidex resin showed the highest color change and the lowest roughness after accelerated aging.

Glass fiber core Vacuum Insulation Panels (VIPs) have thermal performance per unit thickness of about 5-10 times higher than the traditionally used building insulation materials such as mineral wool, XPS, EPS, foam, etc. This advantage of VIP has made it very attractive new option for innovative building designs. Especially in Canada, where some of the areas have long and very cold winters. Confidence in the service life of a building material is necessary before putting a product to market. Extensive research has been conducted on the product development, quality improvement, and field application of VIPs around the world. However, there is lack of consistent and simple prediction method for the long-term thermal performance of VIPs. This paper discussed the process and performance of a field project using glass fiber VIPs to retrofit a commercial building in Yukon, Canada. The thermal performance of the VIPs used in this project was continuously monitored and critically analyzed since the start in 2011. The results have shown satisfactory thermal performance of VIPs for the past 8 years. The findings were also used to validate glass fiber core VIP accelerated aging tests conducted by the National Research Council Canada (Ottawa), and the aging rate of VIPs in a cold and dry climate was determined. The second part of this study investigated the monitored performance results from two sets of simplified accelerated laboratory aging tests, the results were analyzed with the aim to separate the impact of air diffusion from water vapour on the long-term thermal performance of glass fiber VIPs. In addition, this study also investigated the potential application of VIPs in balcony constructions to reduce heat transfer through thermal bridges. Computer modeling exercises, using a benchmarked (EN ISO 10211) three-dimensional transient and steady-state heat transfer simulation tool HEAT3, were carried out on the most optimal (thermal performance) balcony assemblies of wood framed buildings using VIP as insulation. This niche application of VIPs can significantly increase the energy efficiency of building envelopes/skins in extreme climates of Canada and elsewhere in the world. / Graduate / 2021-11-06

Oxidative processes are linked to a number of major disease states as well as the breakdown of many materials. Of particular importance are reactive oxygen species (ROS), as they are known to be endogenously produced in biological systems as well as exogenously produced through a variety of different means. In hopes of better understanding what controls the behavior of ROS, researchers have studied radical chemistry on a fundamental level. Fundamental knowledge of what contributes to oxidative processes can be extrapolated to more complex biological or macromolecular systems. Fundamental concepts and applied data (i.e. interaction of ROS with polymers, biomolecules, etc.) are critical to understanding the reactivity of ROS. A detailed review of the literature, focusing primarily on the hydroxyl radical (HO•) and hydrogen atom (H•) abstraction reactions, is presented in Chapter 1. Also reviewed herein is the literature concerning high density polyethylene (HDPE) degradation. Exposure to treated water systems is known to greatly reduce the lifetime of HDPE pipe. While there is no consensus on what leads to HDPE breakdown, evidence suggests oxidative processes are at play. The research which follows in Chapter 2 focuses on the reactivity of the hydroxyl radical and how it is controlled by its environment. The HO• has been thought to react instantaneously, approaching the diffusion controlled rate and showing little to no selectivity. Both experimental and calculational evidence suggest that some of the previous assumptions regarding hydroxyl radical reactivity are wrong and that it is decidedly less reactive in an aprotic polar solvent than in aqueous solution. These findings are explained on the basis of a polarized transition state that can be stabilized via the hydrogen bonding afforded by water. Experimental and calculational evidence also suggest that the degree of polarization in the transition state will determine the magnitude of this solvent effect. Chapter 3 discusses the results of HDPE degradation studies. While HDPE is an extremely stable polymer, exposure to chlorinated aqueous conditions severely reduces the lifetime of HDPE pipes. While much research exists detailing the mechanical breakdown and failure of these pipes under said conditions, a gap still exists in defining the species responsible or mechanism for this degradation. Experimental evidence put forth in this dissertation suggests that this is due to an auto-oxidative process initiated by free radicals in the chlorinated aqueous solution and propagated through singlet oxygen from the environment. A mechanism for HDPE degradation is proposed and discussed. Additionally two small molecules, 2,3-dichloro-2-methylbutane and 3-chloro-1,1-di-methylpropanol, have been suggested as HDPE byproducts. While the mechanism of formation for these products is still elusive, evidence concerning their identification and production in HDPE and PE oligomers is discussed. Finally, Chapter 4 deals with concluding remarks of the aforementioned work. Future work needed to enhance and further the results published herein is also addressed. / Ph. D.