O presente trabalho teve como objetivo avaliar a emissão de metano por cordeiros alimentados em diferentes pastagens tropicais: Panicum maximum cv. IZ-5 (capim aruana) e Cajanus cajan cv. anão (feijão guandu), e suas relações com a composição química destas pastagens. Os trabalhos foram conduzidos na Estação Experimental Agronômica da UFRGS, nos anos de 2015 e 2016. O delineamento experimental foi de blocos completos casualizados com três repetições. O capítulo II relata os resultados da emissão de metano por cordeiros pastejando nos seguintes tratamentos: 1) ARU – somente capim aruana; 2) FG - somente feijão Guandu; 3) AFG – meio piquete com capim aruana, e a outra metade com feijão Guandu. Para avaliação de metano foi utilizado a técnica com marcador SF6 . No experimento do capítulo II, utilizou-se parcela subdividida, sendo a subparcela dois animais testes que receberam polietileno glicol (PEG) para quelar o tanino presente no feijão guandu, e dois que receberam água como controle. As emissões de metano por consumo de matéria seca (EMICONMSDIA) não apresentaram diferença entre os tratamentos, mesmo considerando as dosificações com polietileno glicol (PEG) ou água (P=0,9235). O tratamento FG (P=0,036) apresentou mais altos níveis de taninos condensados do que os demais tratamentos Apesar de diferenças nas suas características químicas, a emissão de metano de cordeiros é semelhante entre pastagens tropicais de capim aruana (Panicum maximum cv. IZ-5), feijão Guandu (Cajanus cajan cv. Anão. Os taninos condensados presentes na forrageira feijão guandu, nas condições experimentais deste trabalho, não demonstraram potencial para contribuir na redução da emissão de metano por cordeiros. No capítulo III, os tratamentos, manejo dos animais e delineamento experimental foram semelhantes ao capítulo II. Os resultados demonstraram que não há uma relação direta entre as características bioquímicas do alimento e a emissão de metano. Essa desassociação entre a emissão de metano e a composição química da pastagem foi constatada tanto quando relacionou-se a emissão por animal (EMI), quanto quando relacionou-se com a emissão por quilograma de matéria seca ingerida (EMICONMSDIA). Conclui-se, então, que não é possível relacionar a emissão de metano de cordeiros com as características químicas das plantas forrageiras tropicais perenes, capim aruana e feijão Guandu. / The researches carried out in the present work had the objective of evaluating the emission of methane by lambs fed on different tropical pastures: Panicum maximum cv. IZ-5 (Aruana grass) and Cajanus cajan cv. dwarf (pigeon pea), and their relationships with the chemical composition of these pastures. The works were conducted at the Experimental Agronomic Station of UFRGS, between January and April 2016, Chapter II; and from February to April 2015, Chapter III. The experimental design was of randomized complete blocks with three replicates. The blocking was carried out with the objective of eliminating variations of slope of the terrain (flat area, sloping at the top and sloping slope). Chapter II reports the results of methane emission by grazing lambs in the following treatments: 1) ARU - only aruana grass; 2) FG - only Guandu beans; 3) AFG - half picket with aruana grass, and the other half with Guandu beans. For methane evaluation, the SF6 marker technique was used. In the experiment of chapter II, a subdivided plot was used, the subplot being two test animals that received polyethylene glycol (PEG) to chelate the tannin present in the pigeon pea, and two that received water as control. Emissions of methane by dry matter intake (EMICONMSDIA) did not show any difference between treatments, even considering the dosages with polyethylene glycol (PEG) or water (P = 0.9235) FG treatment (P = 0.036) presented higher levels of condensed tannins than the other treatments. Despite differences in their chemical characteristics, the methane emission of lambs is similar between tropical pastures of Aruana grass (Panicum maximum cv. IZ-5), Guandu beans (Cajanus cajan cv. Dwarf), and when these forages are offered at will , in two lanes in the picket. The condensed tannins present in the forage pigeon pea, under the experimental conditions of this work, did not demonstrate the potential to contribute in the reduction of the methane emission by lambs. In Chapter III, treatments, animal management and experimental design were similar to Chapter II. The relationships between the chemical composition of pastures of nutritional influence showed to be quite variable in the methane emission response. The results showed that there is no direct relationship between the biochemical characteristics of the food and the emission of methane. This dissociation between the methane emission and the chemical composition of the pasture was verified both when the emission per animal (EMI) was related and when it was related to the emission per kilogram of ingested dry matter (EMICONMSDIA). It is concluded that it is not possible to relate the emission of methane with the chemical characteristics of perennial tropical forage plants Panicum maximum cv. IZ-5, and Cajanus cajan cv. Dwarf.

The effect of incorporation two clays; layered double hydroxides (LDH) and montmorillonite layered silicates (MLS) in linear low density polyethylene (PE) matrix was investigated. MLS and LDH were added of 5, 15, 30 and 60 weight percent in the PE and compounded using a Brabender. Ground pellets were subsequently compression molded. Dispersion of the clays was analyzed using optical microscopy, SEM and XRD. Both the layered clays were immiscible with the PE matrix and agglomerates formed with increased clay concentration. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Both clays served as nucleation enhancers increasing recrystallization temperatures in the composites. Flame retarding properties were determined by using the flammability HVUL-94 system. LDH indicated better flame retarding properties than MLS for PE. The char structure was analyzed by environmental scanning electron microscopy. Mechanical properties were studied by tensile testing and Vickers microhardness testing apparatus.

京都大学 / 0048 / 新制・論文博士 / 博士(工学) / 乙第13337号 / 論工博第4186号 / 新制||工||1740(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 瀧川 敏算, 教授 中村 洋, 教授 古賀 毅 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Abstract The cold spray process is an additive manufacturing technology primarily suited for ductile metals, and mainly utilized in coating surfaces, manufacturing of freeform parts and repair of damaged components. The process involves acceleration of solid micro-particles in a supersonic gas flow and coating build-up by bonding upon high velocity impact onto a substrate. Coating deposition relies on the kinetic energy of the particles. The main objective of this study was to investigate the mechanics of polymer cold spray process and deformation behavior of polymers to improve technological implementation of the process. A finite element model was created to simulate metal particle impact for copper and aluminum. These results were compared to the numerical and experimental results found in the literature to validate the model. This model was then extended to cover a wide range of impact conditions, in order to reveal the governing mechanisms of particle impact and rebound during cold spray. A systematic analysis of a single high-density polyethylene particle impacting on a semi-infinite high density polyethylene substrate was carried out for initial velocities ranging between 150m/s and 250m/s by using the finite element analysis software ABAQUS. A series of numerical simulations were performed to study the effect of a number of key parameters on the particle impact dynamics. These key parameters include: particle impact velocity, particle temperature, particle diameter, and particle density, composition of the polyethylene particle, surface composition and the thickness of a polyethylene film on a hard metal substrate. The effect of these parameter variations were quantified by tracking the particle temperature, deformation, plastic strain and rebound kinetic energy. The variation of these parameters helped define a window of deposition where the particle is mostly likely to adhere to the substrate.

This Master’s thesis deals with the problematics of radically initiated compounding of polyethylene by 1-vinyladamantane. Theoretical part focuses on the theory of grafting processes and how they are influenced by chosen process parameters, as well as the properties of used monomer. In experimental part, two sets of experiments were designed, in both cases the chemicals used were polyethylene LITEN MB 87, (2,5-dimethyl-2,5-bis(tert-butylperoxy) hexane), also called Trigonox 101, as the initiator, and chemicals called Ionol and Irgafos 168 as stabilizers. The experiments were carried out in a Brabender batch mixer, the temperature was 180 – 185 °C, the reaction time was 5 minutes. The analytic methods used to evaluate the prepared samples’ properties were the tensile testing, the Charpy notch test, measuring of the melt flow index, analyzing the torque during kneading and the analysis of infrared spectra of the samples. By carrying out of these experiments it was found that excessive crosslinking was present with mass fraction of initiator being as low as 2 %. It was also concluded that under these conditions the modification does not improve tensile properties of the material, but it does improve the impact strength, albeit slightly. The influence of the modification on flow properties needs to be investigated further. A presence of vinyl groups was observed in infrared spectra, suggesting the presence of ungrafted vinyladamantane.

Polymeric materials are widely used in diverse applications. However, a major weakness in the majority of the thermoplastic polymers is their lack of ability to resist fire. Most of the chemicals and additives currently used to improve fire retardancy have deleterious effects on the environment. This research focuses on developing an environmentally safe and effective fire-retardant system for high density polyethylene (HDPE), using cellulose nanocrystals (CNCs) and zinc oxide (ZnO). The effect of CNCs coated with nano ZnO has been investigated for improving the fire resistance properties of the HDPE. Improved dispersion of CNCs into HDPE matrix was achieved by employing maleic anhydride as a coupling agent. It was found that addition of CNCs-ZnO can introduce a reasonable level of flame retardancy in HDPE matrix in addition to improving the maximum tensile strength and elongation at break.

The Department of Physics and Astronomy in Uppsala is planning to construct a source-based neutron irradiation facility at Ångströms laboratory. The purpose of this facility will, as of now, mainly be for students and employees to conduct scientific experiments and to calibrate the university's neutron scintillator detectors. A vital part of the construction is the shielding of the source, for both safety reasons and practicality issues. In this project, a series of simulations were made to determine the necessary dimensions of the shielding to ensure that the radiation dose levels stayed under the stipulated 6 mSv per year. Two types of shielding materials were tested, borated and non-borated polyethylene. It was found that the borated polyethylene performed better in shielding the source, but not enough to justify the higher material cost. The optimal dimensions of the shielding for non-borated polyethylene were found to be 60x60x74cm.

The thesis deals with HDPE modification by crosslinking. In the theoretical part, data available in the literature were reviewed. Modifications of the selected HDPE copolymer grade were carried out in a kneading device Brabender using 25 ml chamber size. After having optimized process conditions, there were performed a series of experiments in dependence on concentration of the initiator. Reological properties of polymer samples were investigated by melt flow indexes measured under different conditions. Changes in crystallinity and melting temperatures were evaluated from DSC heat flow measurements. The samples meeting characteristics supposed were selected for measuring complex viscosity on the Rheometer AR-G2 TA and for testing some mechanical properties on the device Zwick.

The presented work deals with the creation of computational model of total hip endoprosthesis and the subsequent stress-strain analysis. The models of geometry of the pelvis and femur were created on base of CT data. In this model were fitted components od endoprosthesis, i.e. femoral stem and acetabular cup (metal and polyethylene pad) and also cement. On this system was subsequently modelled the rals loads conditions. Just the real loading of the prosthesis leads to the wear. It has a great influence on the quality of bone tissue, what is deteriorated. The deteriorated tissue was simulated under the acetabular component. The behaviour of the whole system is assessed on base of stress-strain analysis. This problems is very topical these days.

Růst krystalů zásadně ovlivňuje morfologii a tím také mechanické vlastnosti semikrystalických polymerů. Tato PhD práce přináší alternativní pohled na popis kinetiky krystalizace v polyolefinech plněných slabě interagujícími částicemi. V nanokompozitních materiálech vysoký specifický povrch plniva i při nízkých plněních zásadně ovlivňuje dynamiku řetězců. V blízkosti povrchu plniva začíná hrát významnou roli zpomalená reptace způsobená jak vzájemnými interakcemi plnivo-polymer tak prostorovým omezením mezi nanočásticemi. Růst krystalů byl zkoumán pomocí polarizovaného optického mikroskopu vybaveného horkým stolkem. Výsledky byly korelovány s teoretickými modely a rozsáhlými počítačovými simulacemi na molekulární úrovni. Pozorovaný pokles rychlosti růstu sférolitů v závislosti na obsahu plniva a molekulové hmotnosti matrice je interpretován na základě imobilizační teorie, tedy, zpomalení reptačního pohybu.