Experimental characterization of the mechanical properties in a thin injection moulded Low-Density Polyethylene (LDPE) plate is per- formed in this work. Anisotropy in LDPE at different material orientations is measured from the Digital Image Correlation (DIC) observation of the specimens during uniaxial tensile test. From the test response and observation from DIC, the studied material is found to be significantly anisotropic. Finite Element simulation (FE-simulation) of in-plane anisotropy of material is carried in AbaqusTM R2020 using available models like Hill48 and Barlat2004. When necessary the simulation plastic potentials for these models are optimized against experimental yield stress ratio (R) and anisotropic ratio (r). To express the nonlinear mechanical behavior, a suitable hardening extrapolation model, namely Swift/Hockett-Sherby is selected from several extrapolation models based on experimental data. To validate the experimental methods, simulation methods and material characterization process, finite element simulation results such as force displacement, strain distribution and different anisotropic related properties are compared with the experimental data. Finally, advantages and disadvantages of different simulation models are discussed.

UV-curing is one of the most commonly used methods for producing hydrogels for soft and hard tissue scaffolds. Spontaneous curing is an alternative method which possesses some advantages in comparison to the conventional UV-curing methods; for example, in situ crosslinking and excluding initiators. The main objective of this study was to investigate promising materials for producing UV and spontaneously cured hydrogels, and subsequently to perform a comparison between the produced hydrogels with regard to their different mechanical and physical properties.Seventeen different hydrogels including five UV-cured and twelve spontaneously cured hydrogels were produced by applying thiol-ene chemistry and by varying precursor materials. Hydrogel systems including di- and tetra- functional PEGs of different lengths (2 kDa and 6 kDa) and two different thiol-crosslinkers (ETTMP 1300 Da and DTT) were subsequently characterized and evaluated. The evaluation tests applied in this study were Raman spectroscopy, weight and volumetric swelling test, leaching test, tensile test, and rheology test. Between all the systems, tetra-acrylated PEG (6 kDa) BisMPA was found to be the most promising system. The pH level of the applied solvent (PBS) for spontaneously cured hydrogels was varied from the physiologically relevant level of 7.4 to 7.0 and 7.8 in order to investigate the dependency of physical and mechanical properties of the hydrogels to this parameter.Spontaneous curing of tetra-acrylated PEG (6 kDa) BisMPA with ETTMP 1300 Da as the thiol-crosslinker, was accomplished within 3½ min in PBS with a pH level of 7.4; and it came out to be the fastest spontaneously cured system between all the tested hydrogels. Increasing the PBS pH level resulted in a faster curing process (accomplished in 1½ min). Spontaneously cured hydrogels generally showed decreased mechanical properties, but improved swelling behavior compared to UV-cured hydrogels. Nevertheless, the discussed system still possessed 50% of the elastic modulus in the tensile test in comparison to the UV-cured state; and showed the highest elastic modulus in comparison to other spontaneously cured systems. The storage modulus of the mentioned hydrogel in the spontaneously cured state was very close to the same parameter in the UV-cured hydrogel based on the same precursors. It also possessed the highest storage modulus between all the spontaneously cured hydrogels. Although the obtained swelling properties of this system were not the highest between all the tested hydrogels, these parameters were still in an acceptable range as for a hydrogel proposed for tissue scaffold application (swelling ratio: 9.72, water content: 89.71%, volumetric swelling ratio: 9.05). Furthermore, the system had the lowest weight loss ratio between all the acrylate-based hydrogels (including both UV and spontaneously cured systems), which along with the Raman spectroscopy results shows the high crosslinking efficiency of the system.

This dissertation is dedicated to the complete structural elucidation of chain-walking polyethylene (CWPE) using state-of-the-art analytical technology, including light and neutron scattering experiments as well as advanced liquid chromatography. In doing so, the structural characteristics of CWPE shall be determined on global and segmental scale in order to clearly differentiate this material class from other classical types of PE. Moreover, it is aimed to clarify the true potential of CW catalysis including possibilities and limitations.

Nanoparticles promise many interesting applications because of their exceptional chemical and physical properties. Therefore nanoparticles offer a pathway for the fabrication of new functional, smart materials. Since the primary particle strongly tends to strong agglomeration, and since the surface of nanoparticles is often not compatible with polymers, it is not possible to disperse single particles homogeneously in a polymer melt. Formations of agglomerates are responsible for strong differences in concentration of the nanoparticles in the material matrix and therefore impede a homogeneous property profile. Furthermore properties of compounds are not only determined by single components, but considerably by the interface between these single components. Hence, a strong chemical and physical adhesion between the constituents is required. Thus, surface modification of nanoparticles is a crucial issue. This work focuses on the control of the particle/polymer interface in composite materials which has a thickness of some nanometers. This interface regulates the compatibility of the surface of the nanoparticles and their environment. This interface is also the place where the transmission of energy between nanoparticle and polymer occurs. The interlayer of this boundary surface should be occupied with functional “primer”-macromolecules that provide at least two types of functional groups: one species of functional group should assure the bonding of the primer to the surface of the nanoparticle, and the second type enables the compatibilizing to the matrix, and when indicated also the covalent adhesion to the ambient polymer system. The macromolecular scaffold of the primer permits the selective adjustment of important interface properties as elasticity, durability and the surface energy of the particle – matrix interface. Within this thesis hyperbranched polyethylene (PEI) imine was used as starting platform for “Quat-Primer Polymers” bearing a multitude of functional moieties in form of primary, secondary and tertiary amino groups. Chapter 2 gives a literature – review on hyperbranched polymers – with focus on PEI, stabilization of colloids by polymers, as well as polymer – “nanocomposites”. In Chapter 3 the reaction of PEI with glycidyltrimethylammonium chloride will be described to obtain hyperbranched polymers that consist of (i) the hyperbranched PEI scaffold, (ii) primary, secondary and tertiary amino groups that can be used for further modification reactions with amino-reactive compounds, and (iii) ammonium moieties that can adsorb to negatively charged surfaces. It will be shown that these Quat-Primer polymers have the ability to stabilize several nanoparticles in water to form aqueous dispersions and that they are capable to partially deagglomerate nanoparticles leading to smaller diameters of the particles in the dispersion. Additionally the reaction of hyperbranched polyethylene imine with glycidol will be described displaying a possibility to change the reactivity of the functional groups and exhibiting that also the generated hydroxyl groups generated by the ring-opening reaction of epoxides with PEI react with epoxide rings to form ether linkages. In Chapter 4 the synthesis of several amino-reactive ATRP initiators will be described and two methods to graft PMMA arms to “Quat-Primer polymers” presented in the previous chapter including the “grafting from” and the “grafting to” technique. These synthesized Quat-Primer polymers bearing ammonium moieties, as well as PMMA arms can be used to fabricate PMMA nanocomposites with homogeneously distributed nanoparticles. The developed method allow for grafting monomers that can be used in ATRP polymerization, including acrylates, acrylonitriles and styrenes, to hyperbranched polyethylene imine. Chapter 5 will display pathways to graft caprolactam derivatives to hyperbranched polyethylene imine to generate Quat-Primer polymers bearing ammonium moieties, as well as caprolactam rings. These quat-primer polymers can be used for the fabrication of PA-6 nanocomposites by dispersing nanoparticles in presence of these Quat-Primer polymers and subsequent polymerization.

The effects of black polyethylene (PE) mulch alone and in combination with plastic film tunnels (Agronet, Reemay, whiteperforated, clear, and clear-slitted) were studied on morphology and yield of sweet corn in North Logan, Utah. Yields of "Miracle" sweet corn (Zea mays L.) were increased significantly by using black PE mulch and with a combination of various types of plastic row covers, as compared to unmulched soil. Standard-growth analysis procedures were conducted to verify responses among treatments. Treatment effects were determined by measuring days to first flowering, ear weight, number of side tillers, cob length, cob circumference, cob fill length, number of rows, and number of kernels missing per cob. Leaf area, plant height, and total shoot dry mass were significantly larger for mulched than for unmulched plants.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第12821号 / 論農博第2794号 / 新制||農||1025(附属図書館) / 学位論文||H26||N4816(農学部図書室) / 31308 / (主査)教授 河田 照雄, 教授 保川 清, 准教授 橋本 渉 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

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[ES] La revalorización del reciclado de plástico de envases se ha convertido en una de las prioridades ambientales más importantes a nivel mundial debido a que el plástico se ha convertido en uno de los materiales más utilizados en la fabricación de envases y productos, debido a sus propiedades de durabilidad, resistencia y bajo coste. Sin embargo, el plástico también es uno de los materiales más difíciles de reciclar debido a su resistencia a la degradación. La revalorización del reciclado de plástico de envases es una solución que puede ayudar a reducir la cantidad de plástico que termina en los vertederos y los océanos. La revalorización del reciclado de plásticos de envases puede ayudar a reducir el impacto ambiental de la producción de plástico. Esto se logra a través de la recogida, el procesamiento y el reciclaje de los plásticos usados. Esto reduce los costes de producción y preserva los recursos naturales. Además, para la revalorización del reciclado de plásticos de envases, se deben mejorar los procesos de reciclaje de plástico. Esto incluye la innovación de nuevas tecnologías y procesos de reciclaje, así como mejorar la eficiencia de los procesos existentes. Además, la revalorización del reciclado también puede ayudar a mejorar la calidad de los plásticos reciclados para que sean aptos para su reutilización. Por tanto, la revalorización del reciclado de plásticos de envases es una solución ecológica y económica para reducir el impacto ambiental de la producción de plásticos. Se ha estudiado la recuperación de materiales poliolefinicos y sus alternativas mediante el reciclado mecánico procedentes de residuos domésticos e industriales de diferente naturaleza, con el fin de conocer la posibilidad de obtener un material capaz de competir en algunos usos con el material virgen. En el trabajo se revisa de una manera inicial los dos principales problemas que nos vamos a encontrar a la hora de realizar el proceso de recuperación. De una parte, la presencia de impurezas de otros materiales plásticos y en otras ocasiones la degradación que sobre el material se ha producido en anteriores procesos o por acción de agentes externos como puede ser la luz solar. En ambos casos encontraremos que el material recuperado presenta una disminución de sus propiedades mecánicas y además dificultades en el proceso de recuperación. La utilización de técnicas de análisis instrumental como la calorimetría diferencial han sido las herramientas utilizadas para predecir la calidad del material recuperado a partir de las características del residuo. Otros de los problemas detectados a la hora de la revalorización del plástico son debido a que hay una amplia variedad de plásticos utilizados que son difícil de separar visualmente en el flujo de residuos, esto representa una diferencia con respecto a aquellos cuyos envases son fáciles de identificar. En aquellos casos que la separación del flujo de residuos es sencilla, obtenemos materiales reciclados de excelente calidad. Esto ocurre en la revalorización de residuos procedentes de la recogida selectiva. Pero esta situación no se puede extrapolar en aquellos casos que aparezcan impurezas. Por ejemplo, la existencia de los anillos aromáticos hace que el Poliestireno presente una baja compatibilidad incluso con polímeros derivados del estireno, como es el caso del Acrilonitrilo-Butadieno-Estireno (ABS), donde es recomendable el uso de compatibilizantes para sus mezclas.¿ / [CA] La revalorització del reciclatge de plàstic d'envasos s'ha convertit en una de les prioritats ambientals més importants a nivell mundial pel fet que el plàstic s'ha convertit en un dels materials més utilitzats en la fabricació d'envasos i productes, per les seves propietats de durabilitat, resistència i baix cost. Tot i això, el plàstic també és un dels materials més difícils de reciclar a causa de la seva resistència a la degradació. La revalorització del reciclatge de plàstic d'envasos és una solució que pot ajudar a reduir la quantitat de plàstic que acaba als abocadors i els oceans. La revalorització del reciclatge de plàstics d¿envasos pot ajudar a reduir l¿impacte ambiental de la producció de plàstic. Això s'aconsegueix a través de la recollida, processament i reciclatge dels plàstics usats. Això redueix els costos de producció i preserva els recursos naturals. A més, per a la revalorització del reciclatge de plàstics d'envasos, cal millorar els processos de reciclatge de plàstic. Això inclou la innovació de noves tecnologies i processos de reciclatge, així com millorar l'eficiència dels processos existents. A més, la revalorització del reciclatge també pot ajudar a millorar la qualitat dels plàstics reciclats perquè siguen aptes per a la seva reutilització. Per tant, la revalorització del reciclatge de plàstics d'envasos és una solució ecològica i econòmica per reduir l'impacte ambiental de la producció de plàstics. S'ha estudiat la recuperació de materials poliolefínics i les alternatives mitjançant el reciclatge mecànic procedents de residus domèstics i industrials de diferent naturalesa, per tal de conèixer la possibilitat d'obtindre un material capaç de competir en alguns usos amb el material verge. Per tant, es revisa d'una manera inicial els dos principals problemes que ens trobarem a l'hora de realitzar el procés de recuperació. D'una banda, la presència d'impureses d'altres materials plàstics i altres vegades la degradació que s'ha produït sobre el material en processos anteriors o per acció d'agents externs com pot ser la llum solar. Habitualment trobarem que el material recuperat presenta una disminució de les propietats mecàniques i més dificultats en el procés de recuperació. La utilització de tècniques d'anàlisi instrumental com la calorimetria diferencial han estat les eines utilitzades per predir la qualitat del material recuperat a partir de les característiques del residu. Altres dels problemes detectats a l'hora de la revalorització del plàstic és perquè hi ha una àmplia varietat de plàstics utilitzats que són difícils de separar visualment en el flux de residus, això representa una diferència respecte a aquells els envasos dels quals són fàcils d'identificar . En aquells casos que la separació del flux de residus és senzilla, obtenim materials reciclats de gran qualitat. Això passa en la revalorització de residus procedents de la recollida selectiva. Però aquesta situació no es pot extrapolar en aquells casos que apareguin impureses. Per exemple, l'existència dels anells aromàtics fa que el Poliestirè presenti una baixa compatibilitat fins i tot amb polímers derivats de l'estirè, com és el cas de l'Acrilonitril-Butadiè-Estirè (ABS), on és recomanable l'ús de compatibilitzants per a les mescles. / [EN] The revaluation of the recycling of plastic packaging has become one of the most important environmental priorities worldwide because plastic has become one of the most used materials in the manufacture of packaging and products, due to its properties of durability, resistance and low cost. However, plastic is also one of the most difficult materials to recycle due to its resistance to degradation. Upgrading plastic packaging recycling is one solution that can help reduce the amount of plastic that ends up in landfills and oceans. The revaluation of the recycling of packaging plastics can help reduce the environmental impact of plastic production. This is achieved through the collection, processing and recycling of used plastics. This reduces production costs and preserves natural resources. In addition, for the revaluation of the recycling of packaging plastics, the plastic recycling processes must be improved. This includes innovating new recycling technologies and processes, as well as improving the efficiency of existing processes. In addition, the revaluation of recycling can also help improve the quality of recycled plastics so that they are suitable for reuse. Therefore, the revaluation of the recycling of packaging plastics is an ecological and economic solution to reduce the environmental impact of plastic production. The recovery of polyolefin materials and their alternatives through mechanical recycling from domestic and industrial waste of different natures have been studied, in order to discover the possibility of obtaining a material capable of competing in some uses with virgin material. In the work, the two main problems that we are going to find when carrying out the recovery process are reviewed in an initial way. On the one hand, the presence of impurities from other plastic materials and on other occasions the degradation that has occurred on the material in previous processes or by the action of external agents such as sunlight. In both cases we will find that the recovered material presents a decrease in its mechanical properties and also difficulties in the recovery process. The use of instrumental analysis techniques such as differential calorimetry have been the tools used to predict the quality of the material recovered from the characteristics of the residue. Other problems detected when it comes to revaluing plastic is due to the fact that there is a wide variety of plastics used that are difficult to visually separate in the waste stream, this represents a difference with respect to those whose containers are easy to identify. . In those cases where the separation of the waste stream is simple, we obtain excellent quality recycled materials. This occurs in the revaluation of waste from selective collection. But this situation cannot be extrapolated in those cases where impurities appear. For example, the existence of aromatic rings means that Polystyrene has low compatibility even with polymers derived from styrene, such as Acrylonitrile-Butadiene-Styrene (ABS), where the use of compatibilizers is recommended for their mixtures. / Peinado López-Cepero, F. (2023). Sistemas de revalorización de poliolefinas procedentes de residuos sólidos urbanos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/194553

Interactions of Asthma Drugs with Artificial Saliva and Mucus. Modeling pulmonary particulate transport requires related biofluid physicochemical properties. Aims included measuring the effects of common aerosol drugs on artificial saliva and diffusivities of asthma medications in mucus. Artificial saliva solutions doped with asthma medications were characterized by pH, interfacial tension, and rheology. To measure diffusion, drug concentration was monitored by time-dependent FTIR spectra, and diffusivity obtained using Fick¡¦s second law. Measured theophylline and albuterol diffusivities were ca. 10-6 cm2/s. Surface Modification of Polymer Films with Light-Emitting Chemicals. To develop a polymer film system that changed color in response to radiation, acid groups of poly(ethylene-co-acrylic acid) were used to attach two light-emitting polymers: 4„S-(octyloxy)-4-biphenylcarboxylic acid and 2,7-bis(bromomethyl)-9,9-dihexyl-9Hluorene. Each reaction step was confirmed using static contact angle goniometry, FTIR spectroscopy, and X-ray photoelectron spectroscopy. UV-Vis and fluorescence spectroscopy measured the absorption spectra. Modified films were irradiated (ƒÜ=254 nm) and produced blue emissions.

The oncogene c-MYC has guanine-rich and complementary cytosine-rich sequences in its P1 promoter region. The P1 promoter is responsible for over 90% of the c-MYC expression. Downregulation of c-MYC expression represents a novel therapeutic approach to more than 50% of all cancers. A stable i-motif formed by the c-MYC C-rich sequence would be an attractive target for cancer treatment. We have previously shown that c-MYC promoter sequences can form stable i-motifs in acidic solution (pH 4.5-5.5). The question is whether c-MYC promoter sequence i-motif will be stable at physiological pH. In this work, we have investigated the stability of mutant c-MYC i-motif in solutions having pH values from 4 to 7 and containing co-solutes or molecular crowding agents. The crowded nuclear environment was modeled by the addition of polyethylene glycol (PEG, having molecular weights from 200 to 12000 g/mol) at concentrations of 10% to 40% w/w. Circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC) were used to establish the presence and stability of c-MYC i-motifs in buffer solutions having pH values of 4 to 7. The results of these studies are: 1) the addition of up to 20% w/w glycerol does not increase i-motif stability, 2) the addition of 30% PEG results in an increase in i-motif stability to pH values as high as 6.7, 3) i-motif stability is increased with increased PEG concentration and increased PEG molecular weight, and 4) the effects of PEG size and concentration are not linear, with larger PEGs forming DNA/PEG complexes, which destabilize the i-motif. In summary, we have shown that the c-MYC i-motif can exist as a stable structure at pH as high as 6.7 in a crowded environment. Molecular crowding, largely an excluded volume effect, drives the formation of the more compact i-motif, even at higher pH values where the cytosine imino-nitrogen is deprotonated and neutral C-C pairs can form only two H-bonds. Based on this research, it seems possible that a stable c-MYC promoter sequence i-motif could form at physiological pH and would be a reasonable drug target for new cancer therapies.