Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 51-52). Also available on the World Wide Web.

Os nervos periféricos são extensões do sistema nervoso central e responsáveis pela interação das atividades das extremidades, em suas funções sensitiva e motora. São vulneráveis aos mesmos tipos de traumas que afetam outros tecidos: contusão, compressão, esmagamento, estiramento, avulsão e laceração. Desta forma, a interrupção de continuidade da estrutura do nervo, por algum tipo de trauma, resulta na interrupção de transmissão dos impulsos nervosos e na desorganização de suas atividades funcionais. Para tanto, em vista da evolução tecnológica e o desenvolvimento de equipamentos mais sofisticados, a microcirurgia vem ganhando cada vez mais espaço no campo da investigação experimental referente a recuperação de nervos periféricos lesionados. Em uma secção simples, sem perda tecidual, a neurorrafia denominada término-terminal apresenta bons resultados, contudo, quando ocorre perda de tecido nervoso ou, não se têm mais os cotos distais do nervo, outras técnicas devem ser empregadas, até porque, não se pode de modo algum tencionar o nervo numa tentativa de coaptá-lo novamente. Várias técnicas de tubulização utilizando-se materiais biológicos e não biológicos, para criar um meio por onde ocorrerá a regeneração nervosa já foram ou ainda estão sendo testados com resultados insatisfatórios sob o aspecto funcional.É sabido que em um trauma sem perda tecidual, numa neuropraxia, por exemplo, o nervo recupera espontaneamente de forma satisfatória. É sabido também que em um feixe vásculo-nervoso, o nervo periférico encontra-se em íntimo contato com a adventícia de artérias e veias. A adventícia dos vasos é constituída por tecido conjuntivo frouxo, rico em adipócitos. Assim, em um trauma, os neuritos oriundos do coto proximal do nervo lesado, ficam diretamente em contato com esses adipócitos. Seguindo este raciocínio, e com base em trabalhos anteriores onde foi usada veia preenchida com músculo esquelético a fresco como enxerto, decidimos testar a possibilidade de crescimento axonal por meio de enxerto com tubo de polietileno preenchido por tecido adiposo autólogo. Para tanto será utilizado um tubo com 12 mm de comprimento por 0,25 mm de diâmetro, com poros de 80 µm de diâmetro, preenchido com tecido adiposo in natura retirado das adjacências do referido nervo, na tentativa de se recuperar o nervo isquiático. A certificação do sucesso da recuperação do nervo será feita por meio de técnicas de microcirurgia, microscopia e morfometria. O enxerto de polietileno mostrou ter resistência a pressões, uma vez que não foi observado colapso estrutural. A gordura mostrou ser bom material trófico já que no grupo onde a utilizou apresentou resultados mais próximos do controle final. / Peripheral nerves are extensions of the central nervous system and are responsible for the interaction of the activities of the extremities in their sensory and motor function. They are vulnerable to these types of injuries that affect other tissues: contusion, compression, crush, stretch, tear and avulsion. Thus, the interruption of continuity of the nerve structure, due to some sort of trauma, results in the interruption of transmission of nerve impulses and disruption of their functional activities. Therefore, in view of technological evolution and development of more sophisticated equipment, microsurgery is gaining more space in the field of experimental research concerning the recovery of injured peripheral nerves. In a single section, without loss of tissue, called the end-terminal neurorrhaphy was also good, however, when there is loss of nervous tissue or, if not longer have the distal nerve stumps, other techniques must be employed, because, in any circumstance the nerve should be tensioned as an attempt to coaptation again. Several techniques of tubing, using biological materials and non-biological means to create a place where nerve regeneration have been or are still being tested with unsatisfactory results in the functional aspect. It is known that in a trauma without loss of tissue, a neuropraxia, for example, the nerve recovers spontaneously and satisfactorily. It is also known that in a neurovascular bundle, the peripheral nerve is in close contact with the adventitia of arteries and veins. The adventitia of the vessels is composed of loose connective tissue rich in adipocytes. Thus, in trauma, the neurites from the proximal stump of injured nerve, are directly in contact with these adipocytes. Following this reasoning, and based on previous work where it was used vein filled with fresh skeletal muscle as a graft, decided to test the possibility of axonal growth by grafting polyethylene tube filled with autologous adipose tissue. For that will be used with a tube 12 mm long and 0.25 mm in diameter, with pores of 80 microns in diameter, filled with fresh adipose tissue removed from the vicinity of that nerve, in an attempt to recover the sciatic nerve. Certification of successful nerve recovery will be done through microsurgical techniques, microscopy and morphometry. The graft polyethylene proved to have pressure resistance, since no structural collapse was observed. The fat was found to be good material as trophic group which had used the results closer to the ultimate control.

Butt fusion welding process is an extensively used method of joining for high density polyethylene (HDPE) pipe. With the increasing number of HDPE resin and pipe manufacturers and the diversity of industries utilising HDPE pipes, a wide range of different standards have evolved to specify the butt fusion welding parameters with inspection and testing methods, to maintain quality and structural integrity of welds. There is a lack of understanding and cohesion in these standards for the selection of welding parameters; effectiveness, accuracy, and selection of the test methods and; correlation of the mechanical properties to the micro and macro joint structure. The common standards (WIS 4-32-08, DVS 2207-1, ASTM F2620, and ISO 21307) for butt fusion welding were used to derive the six welding procedures. A total of 48 welds were produced using 180 mm outer diameter SDR 11 HDPE pipe manufactured from BorSafe™ HE3490-LS black bimodal PE100 resin. Three short term coupon mechanical tests were conducted. The waisted tensile test was able to differentiate the quality of welds using the energy to break parameter. The tensile impact test due to specimen geometry caused the failure to occur in the parent material. The guided side bend specimen geometry proved to be too ductile to be able to cause failures. A statistical t-test was used to analyse the results of the short term mechanical tests. The circumferential positon of the test specimen had no impact on their performance. Finite element analysis (FEA) study was conducted for the long term whole pipe tensile creep rupture (WPTCR) test to find the minimum length of pipe required for testing based on pipe geometry parameters of outer diameter and SDR. Macrographs of the weld beads supplemented with heat treatment were used to derive several weld bead parameters. The FEA modelling of the weld bead parameters identified the length to be a key parameter and provided insight into the relationship between the geometry of the weld beads and the stresses in the weld region. The realistic bead geometry digitised using the macrographs contributed a 30% increase in pipe wall stress due to the stress concentration effect of the notches formed between the weld beads and the pipe wall. The circumferential position of the weld bead had no impact on the pipe wall stresses in a similar manner to the results of the different mechanical tests. IV Nanoindentation (NI) and differential scanning calorimetry (DSC) techniques were used to study the weld microstructure and variation of mechanical properties across the weld at the resolutions of 100 and 50 microns, respectively. NI revealed signature 'twin-peaks and a valley' distribution of hardness and elastic modulus across the weld. The degrees of crystallinity obtained from DSC followed the NI pattern as crystallinity positively correlates with the material properties. Both techniques confirm annealing of the heat affected zone (HAZ) material towards the MZ from the parent material. The transmission light microscopy (TLM) was used to provide dimensions of the melt zone (MZ) which displays an hour glass figure widening to the size of the weld bead root length towards the pipe surfaces. Thermal FEA modelling was validated using both NI and TLM data to predict the HAZ size. The HAZ-parent boundary temperature was calculated to be 105 ⁰C. The 1st contribution of the study is to prove the existence of a positive correlation between the heat input calculated from FEA and the energy to break values obtained from the waisted tensile test. The 2nd contribution providing the minimum length of pipe for WPTCR based on the pipe dimensions. The 3rd contribution is the recommendation for the waisted tensile test with the test using the geometry designed to minimise deformation of the loading pin holes. The 4th contribution related the weld bead parameters to pipe wall stresses and the effect of notches as stress concentrators. The 5th contribution is a new method of visualising a welding procedure that can be used to not only compare the welding procedures but also predict the size of the MZ and the HAZ. The 6th contribution of the study is the proposal of new weld bead geometry that consist of the MZ bounded by the HAZ, for butt fusion welded joints of HDPE pipes.

Os nervos periféricos são extensões do sistema nervoso central e responsáveis pela interação das atividades das extremidades, em suas funções sensitiva e motora. São vulneráveis aos mesmos tipos de traumas que afetam outros tecidos: contusão, compressão, esmagamento, estiramento, avulsão e laceração. Desta forma, a interrupção de continuidade da estrutura do nervo, por algum tipo de trauma, resulta na interrupção de transmissão dos impulsos nervosos e na desorganização de suas atividades funcionais. Para tanto, em vista da evolução tecnológica e o desenvolvimento de equipamentos mais sofisticados, a microcirurgia vem ganhando cada vez mais espaço no campo da investigação experimental referente a recuperação de nervos periféricos lesionados. Em uma secção simples, sem perda tecidual, a neurorrafia denominada término-terminal apresenta bons resultados, contudo, quando ocorre perda de tecido nervoso ou, não se têm mais os cotos distais do nervo, outras técnicas devem ser empregadas, até porque, não se pode de modo algum tencionar o nervo numa tentativa de coaptá-lo novamente. Várias técnicas de tubulização utilizando-se materiais biológicos e não biológicos, para criar um meio por onde ocorrerá a regeneração nervosa já foram ou ainda estão sendo testados com resultados insatisfatórios sob o aspecto funcional.É sabido que em um trauma sem perda tecidual, numa neuropraxia, por exemplo, o nervo recupera espontaneamente de forma satisfatória. É sabido também que em um feixe vásculo-nervoso, o nervo periférico encontra-se em íntimo contato com a adventícia de artérias e veias. A adventícia dos vasos é constituída por tecido conjuntivo frouxo, rico em adipócitos. Assim, em um trauma, os neuritos oriundos do coto proximal do nervo lesado, ficam diretamente em contato com esses adipócitos. Seguindo este raciocínio, e com base em trabalhos anteriores onde foi usada veia preenchida com músculo esquelético a fresco como enxerto, decidimos testar a possibilidade de crescimento axonal por meio de enxerto com tubo de polietileno preenchido por tecido adiposo autólogo. Para tanto será utilizado um tubo com 12 mm de comprimento por 0,25 mm de diâmetro, com poros de 80 µm de diâmetro, preenchido com tecido adiposo in natura retirado das adjacências do referido nervo, na tentativa de se recuperar o nervo isquiático. A certificação do sucesso da recuperação do nervo será feita por meio de técnicas de microcirurgia, microscopia e morfometria. O enxerto de polietileno mostrou ter resistência a pressões, uma vez que não foi observado colapso estrutural. A gordura mostrou ser bom material trófico já que no grupo onde a utilizou apresentou resultados mais próximos do controle final. / Peripheral nerves are extensions of the central nervous system and are responsible for the interaction of the activities of the extremities in their sensory and motor function. They are vulnerable to these types of injuries that affect other tissues: contusion, compression, crush, stretch, tear and avulsion. Thus, the interruption of continuity of the nerve structure, due to some sort of trauma, results in the interruption of transmission of nerve impulses and disruption of their functional activities. Therefore, in view of technological evolution and development of more sophisticated equipment, microsurgery is gaining more space in the field of experimental research concerning the recovery of injured peripheral nerves. In a single section, without loss of tissue, called the end-terminal neurorrhaphy was also good, however, when there is loss of nervous tissue or, if not longer have the distal nerve stumps, other techniques must be employed, because, in any circumstance the nerve should be tensioned as an attempt to coaptation again. Several techniques of tubing, using biological materials and non-biological means to create a place where nerve regeneration have been or are still being tested with unsatisfactory results in the functional aspect. It is known that in a trauma without loss of tissue, a neuropraxia, for example, the nerve recovers spontaneously and satisfactorily. It is also known that in a neurovascular bundle, the peripheral nerve is in close contact with the adventitia of arteries and veins. The adventitia of the vessels is composed of loose connective tissue rich in adipocytes. Thus, in trauma, the neurites from the proximal stump of injured nerve, are directly in contact with these adipocytes. Following this reasoning, and based on previous work where it was used vein filled with fresh skeletal muscle as a graft, decided to test the possibility of axonal growth by grafting polyethylene tube filled with autologous adipose tissue. For that will be used with a tube 12 mm long and 0.25 mm in diameter, with pores of 80 microns in diameter, filled with fresh adipose tissue removed from the vicinity of that nerve, in an attempt to recover the sciatic nerve. Certification of successful nerve recovery will be done through microsurgical techniques, microscopy and morphometry. The graft polyethylene proved to have pressure resistance, since no structural collapse was observed. The fat was found to be good material as trophic group which had used the results closer to the ultimate control.

The design of polyethylene (PE) pipelines for applications in the gas, water and chemical process industries has been based on data mainly obtained from stress rupture testing pipes only. In practice, installations are composed of both extruded pipe and injection moulded fittings which are joined by a fusion welding technique and are very often subjected to internal pressures of a fluctuating nature. Several makes of PE pipe systems were therefore obtained and work was undertaken to fully characterise mechanical performance in terms of internal pressure loadings. Butt-welded test specimens comprising pipe lengths and fittings were subjected to both static and fluctuating conditions at 80°C, at pressures resulting in brittle fractures (below the knee on stress rupture curves) and at frequencies not exceeding 7.5 cpm (0.125 Hz). Resulting fracture surfaces were examined to identify sources of crack initiation and mechanisms of failure. Mechanical behaviour of the PE pipe samples was found to be markedly influenced by the grade of plastics compound, the pipe system dimensions, mould designs and methods of processing. Fatigue loading was the most aggressive test method and significant reductions in lifetimes were observed in fittings or joints between pipes and fittings with only modest increases in the frequency of pressurisation. It was also demonstrated that improved stress rupture behaviour did not necessarily lead to better fatigue performance. For the square-wave loading profiles used, an idea of the relevant failure mechanisms in any given system was obtained by comparing experimental Nf values with those predicted from cumulative damage principles based on Nf=τSR/τmax. In all types of system, failure was initiated at a defect residual from processing or jointing. Over 95% of all small diameter pipe fractures originated from inclusions at or close to the inside wall. They were geometrically and elementally analysed and suggestions made as to their possible origin and means of elimination. For one PE a reasonable correlation was obtained, between lifetime under stress rupture or fatigue and the inclusion size as measured in the fracture plane.

No description available.

Properties of both chemical contaminants and polymers can impact contaminant diffusivity and solubility in new and aged polyethylene materials for pipes and geomembranes. Diffusivity, solubility, polymer and chemical properties were measured for thirteen contaminants and six polyethylene materials that were new and/or aged in chlorinated water. Tree regression was used to select variables, and linear regression was used to develop predictive equations for contaminant diffusivity and solubility in polyethylene. Organic contaminant properties had greater predictive capability than polyethylene properties. Model coefficients significantly changed between new materials to chlorine-aged materials, indicating changes of polyethylene properties impact the interaction between contaminants and polymers. The metallic flavor of copper in drinking water influences the taste of water and can cause the taste problems for water utilities. The mechanism of metallic flavor caused by these metals is related to free or soluble ions. Free copper concentrations were measured at different pH in diluted artificial saliva using a cupric ion selective electrode. Three major proteins in human saliva: α-amylase, mucin and lactoferrin, were added in the artificial saliva and the impacts on the chemical speciation of copper were analyzed. Inorganic saliva components, typically phosphate, carbonate and hydroxide combined with copper and greatly influenced the levels of free copper in the oral cavity. Proteins such as α-amylase, mucin and lactoferrin also impacted the chemical speciation of copper, with different affinity to copper. Mucin had the greatest affinity with copper than α-amylase. / Master of Science

The damaging impact of continuous utility cuts on flexible pavement performance has been shown to be a major problem for urban roads and pavement mangers due to high reconstruction and maintenance costs. Horizontal Directional Drilling (HDD) is a trenchless construction method that does not require continuous trenching. HDD pipe installation techniques can reduce reinstatement costs, shorten construction periods, and lower social costs due to reduced user traffic delays. In this thesis, a detailed field study and numerical investigations was completed to quantify pavement deterioration and polyethylene (PE) pipe performance when pipelines are installed under flexible pavements using both traditional open-cut and HDD construction methods. Two 200mm SDR-17 DIPS HDPE pipes were installed 1.5m below a flexible pavement using open-cut and HDD construction technique. A state-of-the-art instrumentation and data acquisition systems were developed to measure HDD drill rig, PE pipes and pavement responses during pipe installations and for a period of about three years afterwards. Field data from (GPR) surveys, falling weight deflectometer (FWD) tests, surface distress surveys, and ground surface elevation survey were used to evaluate pavement deterioration due to the pipeline installations. The mechanisms of ground deformations during HDD and open-cut pipe installation were numerically investigated with FLAC3D, a commercial finite difference program. A hybrid constitutive model consisting of the traditional Duncan-Chang hyperbolic model and Mohr-Coulomb perfectly plastic model was developed and implemented in FLAC3D to simulate the non-linear stress-strain and stress dependent behavior of granular materials. Field test results show that the HDD installed pipe have significantly lower construction induced strains and ring deflections when compared to the open cut-and-cover installation and the mechanism of pipe deformation differs for the two construction techniques. The two pipes performed satisfactory over the long-term monitoring period as deflections and strain levels were below acceptable limits and there was no apparent deterioration of the pipe. Pipe deflections resulting from environmental effects (freeze and thaw) were found to be more significant than those due to material creep. Furthermore, the modified Iowa’s and Plastic Pipe Institute’s (PPI) ring deflection equations were found to over estimate pipe deflection for the open-cut and HDD installed pipes by about 114 and 50 percent, respectively. Results from field tests found that the HDD installation did not results in any observable change in the condition of the pavement structure performance, while the structure and integrity of pavement section in the vicinity of the open-cut was adversely impacted by utility cut excavation. It was determined numerically that when an unsupported excavation is created within a typical flexible pavement structure, distress zones that extend laterally from the face of the excavation to a distance of approximately 80% of the depth of excavation is developed. The results of the analyses suggests that better restoration techniques are required to eliminate the adverse effect caused by the stress relief within the pavement structure during a utility cut. Furthermore, the area of potential pavement deterioration should be extended beyond the edge of the utility cut to encompass the ‘distress zones’ when determining fees to cover pavement damage and restoration costs. Results obtained from numerical simulations advanced the understanding of the mechanism, magnitude, and extent of deformation within the pavement structure during HDD pipe installation in frictional and cohesive subgrade soils. Relationship between HDD annular bore pressures and displacements have been incorporated into design Charts and Tables for use in estimating maximum allowable bore pressures for HDD installation beneath flexible pavements. Critical bore pressures that would limit ground deformations and prevent excessive pavement deformations are presented. Critical bore pressures were compared to estimated allowable bore pressures obtained from the widely used Delft Geotechnics equation. The Delft Geotechnics equation was found to over estimate allowable bore pressure for HDD installation beneath flexible pavement. HDD pipeline installations under flexible pavement were found to have significantly lower restoration costs, social costs and maintenance cost than open-cut pipeline installations.

The damaging impact of continuous utility cuts on flexible pavement performance has been shown to be a major problem for urban roads and pavement mangers due to high reconstruction and maintenance costs. Horizontal Directional Drilling (HDD) is a trenchless construction method that does not require continuous trenching. HDD pipe installation techniques can reduce reinstatement costs, shorten construction periods, and lower social costs due to reduced user traffic delays. In this thesis, a detailed field study and numerical investigations was completed to quantify pavement deterioration and polyethylene (PE) pipe performance when pipelines are installed under flexible pavements using both traditional open-cut and HDD construction methods. Two 200mm SDR-17 DIPS HDPE pipes were installed 1.5m below a flexible pavement using open-cut and HDD construction technique. A state-of-the-art instrumentation and data acquisition systems were developed to measure HDD drill rig, PE pipes and pavement responses during pipe installations and for a period of about three years afterwards. Field data from (GPR) surveys, falling weight deflectometer (FWD) tests, surface distress surveys, and ground surface elevation survey were used to evaluate pavement deterioration due to the pipeline installations. The mechanisms of ground deformations during HDD and open-cut pipe installation were numerically investigated with FLAC3D, a commercial finite difference program. A hybrid constitutive model consisting of the traditional Duncan-Chang hyperbolic model and Mohr-Coulomb perfectly plastic model was developed and implemented in FLAC3D to simulate the non-linear stress-strain and stress dependent behavior of granular materials. Field test results show that the HDD installed pipe have significantly lower construction induced strains and ring deflections when compared to the open cut-and-cover installation and the mechanism of pipe deformation differs for the two construction techniques. The two pipes performed satisfactory over the long-term monitoring period as deflections and strain levels were below acceptable limits and there was no apparent deterioration of the pipe. Pipe deflections resulting from environmental effects (freeze and thaw) were found to be more significant than those due to material creep. Furthermore, the modified Iowa’s and Plastic Pipe Institute’s (PPI) ring deflection equations were found to over estimate pipe deflection for the open-cut and HDD installed pipes by about 114 and 50 percent, respectively. Results from field tests found that the HDD installation did not results in any observable change in the condition of the pavement structure performance, while the structure and integrity of pavement section in the vicinity of the open-cut was adversely impacted by utility cut excavation. It was determined numerically that when an unsupported excavation is created within a typical flexible pavement structure, distress zones that extend laterally from the face of the excavation to a distance of approximately 80% of the depth of excavation is developed. The results of the analyses suggests that better restoration techniques are required to eliminate the adverse effect caused by the stress relief within the pavement structure during a utility cut. Furthermore, the area of potential pavement deterioration should be extended beyond the edge of the utility cut to encompass the ‘distress zones’ when determining fees to cover pavement damage and restoration costs. Results obtained from numerical simulations advanced the understanding of the mechanism, magnitude, and extent of deformation within the pavement structure during HDD pipe installation in frictional and cohesive subgrade soils. Relationship between HDD annular bore pressures and displacements have been incorporated into design Charts and Tables for use in estimating maximum allowable bore pressures for HDD installation beneath flexible pavements. Critical bore pressures that would limit ground deformations and prevent excessive pavement deformations are presented. Critical bore pressures were compared to estimated allowable bore pressures obtained from the widely used Delft Geotechnics equation. The Delft Geotechnics equation was found to over estimate allowable bore pressure for HDD installation beneath flexible pavement. HDD pipeline installations under flexible pavement were found to have significantly lower restoration costs, social costs and maintenance cost than open-cut pipeline installations.

Bimodal polyethylene resins are frequently used for pipe applications. In this work, blending was used to produce polyethylenes with comparable properties, particularly with respect to processing, stress crack resistance and tensile properties. Suitable blend components were identified, and their performance screened used ECHIP experimental design software. Blends were characterized using gel permeation chromatography (GPC), differential scanning calorimetry (DSC), tensile testing, stress crack resistance measurements, impact toughness testing, capillary rheometry and melt index measurements. GPC, DSC and melt index results reveal that the method of meltcompounding produced morphologically uniform blends, with different degrees of compatibility depending on the type and level of branching of blend components. Most of the blends produced showed higher crystallinity values compared to a reference bimodal resin. Binary high density polyethylene (HDPE) blends showed better stiffness and strength properties, whereas metallocene catalyzed linear low density polyethylene (mLLDPE) containing blends illustrated superior elongation and toughness properties compared to the reference polymer and other binary blends. The highest resistance to slow crack growth (SCG) was shown by low density polyethylene (LDPE) and mLLDPE containing blends due to their high branching content. The overall blend resistance to SCG or toughness can be enhanced with levels less than 20% by weight of LDPE or mLLDPE in the blend although the tensile properties are relatively unaffected at these low concentrations. The performance of blends was optimized by changing component polymers and their weight fractions, and a model to predict optimum blends was developed using the Maple code. Optimized blends showed higher branching content, comparable molecular weight, molecular weight distribution, tensile properties, viscosity and processing behaviour to the reference polymer. Optimized blend 3, in particular, encountered the same degree of shear thinning as the reference material. Better toughness and resistance to SCG were shown by the optimized blends when compared to the reference polymer.