Yes / We present hot melt extrusion (HME) for the design of floating multiparticulates. Metoprolol succinate was selected as the model drug. Our foremost objective was to optimize the components Eudragit® RS PO, polyethylene oxide (PEO) and hydroxypropyl methylcellulose (HPMC) to balance both buoyancy and controlled release. Gas generated by sodium bicarbonate in acidic medium was trapped in the polymer matrix to enable floating. Eudragit® RS PO and PEO with sodium bicarbonate resulted in multiparticulates which exhibited rapid flotation within 3 minutes but inadequate total floating time (TFT) of 3 hours. Addition of HPMC to the matrix did not affect floating lag time (FLT), moreover TFT increased to more than 12 hours with controlled release of metoprolol succinate. Floating multiparticulates exhibited t50% of 5.24 hours and t90% of 10.12 hours. XRD and DSC analysis revealed crystalline state of drug while FTIR suggested nonexistence of chemical interaction between the drug and the other excipients. The assay, FLT, TFT and the drug release of the multiparticulates were unchanged when stored at 40 °C/75%RH for 3 months confirming stability. We present floating multiparticulates by HME which could be extrapolated to a range of other drugs. Our approach hence presents platform technology for floating multiparticulates.

Yes / Active packaging consisting of polyethylene terephthalate (PET) trays coated with a Citrus extract, without and with plasma pre-treatment, can reduce lipid oxidation in cooked meat. The mechanism of action of the packaging was investigated by quantifying the extent of transfer of antioxidant components from the active packaging into cooked turkey meat. Kinetic studies revealed the affinity for water of phenolic compounds and carboxylic acids in the Citrus extract, suggesting their diffusion into the water phase of the meat facilitated their antioxidant effect. Analysis by high-performance liquid chromatography permitted the identification of carboxylic acids and flavanones as major components of the extract. Their quantification in meat after contact with the trays revealed a release of 100% of the total coated amount for citric acid, 30% for salicylic acid, 75% for naringin and 58% for neohesperidin, supporting the release of these components into cooked meat as a mechanism of action of the antioxidant active packaging.

No

The three-stage (extrusion, annealing, stretching) method of producing microporous membranes from linear polyethylene (HDPE) was investigated in this dissertation. Two different HDPE resins with identical M̅_n (14,600) values but different distributions (M̅_w/M̅_n=10.3, 15.1) were utilized for this study. In the extrusion process, the two HDPE resins were melt extruded into uniaxially oriented tubular films. Systematical changes were made in the process variables -- these being the melt temperature at the die exit, the quench height, the cooling rate, and the line speed. The melt relaxation time behavior of the HDPE resins was studied by a Carreau-Yasuda analysis. The orientation morphological features of the extruded films were examined by TEM, HSEM, birefringence, WAXS, SAXS, and linear IR dichroism. The molecular weight distribution of the raw resins as well as the specific processing variables of quench height and melt temperature were found to be important in determining the final structure of the HDPE extruded films. Following the extrusion process, the effect of annealing on the structure and properties of the HDPE extruded films was investigated. The HDPE extruded films were annealed under different conditions. The annealing variables studied included the temperature, the line speed (or annealing time), and the amount of extension applied during annealing. The extruded films before and after annealing were characterized by DSC, WAXS, SAXS, birefringence, and TEM. The results suggest that upon annealing, perfection of the crystalline phase occurs by removal of the defects from the crystalline phase. In the last step, the precursors (either the extruded films or the extruded films after being annealed) were uniaxially deformed along the extrusion direction. The variables of cold stretch ratio, hot stretch ratio, and total stretch percent were varied to alter the properties of the stretched microporous membranes. The pore structure, porosity, and permeability of the stretched microporous films were analyzed by TEM, HSEM, AFM, DSC, and Gurley number measurements. The importance of the orientation and morphological properties of the precursors, the annealing effects of the HDPE extruded films, and the stretching variables for influencing the microporosity behavior of the HDPE microporous membranes is clearly made evident in this dissertation. / Ph. D.

The role of the single component instability of surface melt fracture on the interface behavior in stratified bicomponent flow has been examined. First, the factors and conditions leading to the onset of surface melt fracture in linear low-density polyethylene (LLDPE) were identified using fluoro-elastomer (FE) as a blending additive and as a die coating in two visualization dies. A visualization die was constructed so that subsequent experiments examining the joining flow behavior of two stratified flows could be examined. Experiments were conducted in the joining flow die over a range of upstream conditions corresponding to surface melt fracture behavior and the resulting flow birefringence patterns and the interface of the extrudate were examined. It was determined from the: single component studies that the role of FE in eliminating surface melt fracture behavior for LLDPE was to introduce slip at the melt/metal interface in the dies. Additionally, it was determined that the coupling of a critical stress with a critical acceleration of the melt as it exits the die, suggested by Kurtz [19], was an accurate description of the behavior observed experimentally. Under upstream conditions corresponding to surface melt fracture behavior, no irregular distortions were observed in the bicomponent interface. It was therefore concluded that the single component instability of surface melt fracture does not play a role in irregular distortions of the interface. Numerical simulations employing the Phan-Thien Tanner (PTT) constitutive model and the finite element method (FEM) were conducted to examine the influence of relaxation times and extensional viscosity on the developing flow region in joining flow die. Numerical predictions employing material constants fit to the rheological properties of LLDPE were compared with the ex- perimental results to establish the reliability of the numerical method. Qualitative agreement between the predictions and the experimental behavior was observed. However, the magnitude of the stresses predicted by the model were not quantitatively accurate. It was concluded that the numerical method was capable of predicting trends in behavior, but was not quantitatively accurate. Given this limitation, it was suggested by the results of the numerical studies that the relaxation behavior has a pronounced effect on the developing stress field, while the impact of the extensional viscosity is minimal. Simulations were also performed to evaluate the ‘stick-slip’ behavior of LLDPE. The results provided additional support to the supposition of the role of FE in eliminating surface melt fracture behavior in LLDPE. / Ph. D.

Crystallisation is gaining a lot of interest in pharmaceutical industry to help designing active ingredients with tailored physicochemical properties. Many factors have been found to affect the crystallisation process, including process parameters and material attributes. Several studies in the literature have discussed the role of these parameters in the crystallisation process. A comprehensive study is still missing in this field where all the significant terms are taken into consideration, including the square effect and the interaction terms between different parameters. In this study, a thorough investigation into the main factors affecting crystallisation of a polymeric system, processed via injection moulding, was presented and a sample of response optimisation was introduced which can be mimicked to suite a specific need. Three grades of pure polyethylene oxide; 20K, 200K and 2M, were first characterised using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD) and shear rheometry. The onset of degradation and the rate varied according to molecular weight of polyethylene oxide (PEO). The peak melting temperature and the difference in enthalpy between melting and crystallisation were both in a direct proportion with PEO molecular weight. PEO200K and PEO2M struggle to recrystallise to the same extent of the original state at the tested cooling rates, while PEO20K can retain up to a similar crystallinity degree when cooled at 1 °C/min. Onset of crystallisation temperature (Tc1) was high for PEO2M and the difference between the 20K and 200K were pronounced at low cooling rate (20K is higher than 200K). The rheometer study showed that PEO2M has a solid-like structure around melting point which explains the difficulty in processing this grade at a low temperature via IM. PEO20K was almost stable within the strain values studied (Newtonian behaviour). For higher grades, PEO showed a shear thinning behaviour. The complex viscosity for PEO2M is characterised by a steeper slope compared to PEO200K, which indicates higher shear thinning sensitivity due to higher entanglement of the longer chains. For binary blends of PEO, the enthalpy of crystallisation studied by DSC was in direct proportion to the lowest molecular weight PEO content (PEOL %) in PEO20K/200K and PEO20K/2M blends. The effect of PEOL% on Tc1 became slightly pronounced for PEO20K-2M blends where Tc1 exhibited slight inverse proportionality to PEOL% and it became more significant for PEO200K-2M blends. It was interesting to find that Tc1 for the blends did not necessarily lie between the values of the homopolymers. In all binary blends, Tc1 was inversely proportional to cooling rate for the set of cooling rates tested. Thermal analysis using hot stage polarised light microscopy yields different behaviours of various PEO grades against the first detection of crystals especially where the lowest grade showed highest detection temperature. Visual observation of PEO binary blends caplets processed at various conditions via injection moulding (IM) showed the low-quality caplets processed at mould temperature above Tc1 of the sample. The factors affecting crystallisation of injection moulded caplets were studied using response surface methodology for two responses; peak melting temperature (Tm) and relative change in crystallinity (∆Xc%) compared to an unprocessed sample. Mould temperature (Tmould) was the most significant factor in all binary blend models. The relationship between Tmould and the two responses was positive non-linear at the Tmould ˂ Tc1. Injection speed was also a significant factor for both responses in PEO20K-200K blends. For Tm, the injection speed had a positive linear relationship while the opposite trend was found for ∆Xc%. The interaction term found in the RSM study for all models was only between the injection speed and the PEOL % which shows the couple effect between these two factors. Molecular effect was considered a significant factor in all ∆Xc% models across the three binary blends. The order of ∆Xc% sensitivity to the change in PEOL% was 3, 5 and 7 % for 20K-200K, 200K-2M and 20K-2M.

[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

[ES] Debido a la gran problemática que concierne el uso de plásticos, se ha incrementado la conciencia social derivada de los problemas medioambientales como la gran cantidad de desechos plásticos generados, la escasez de petróleo, el aumento de la huella de carbono y la contaminación. Como medida alternativa, aparece el uso de materiales de origen natural, consiguiendo reducir con éxito el uso de recursos no renovables y disminuir la cantidad de huella de carbono. Dentro de la industria del plástico, el polietileno de alta densidad (HDPE) es unos de los plásticos comerciales más utilizados, por lo que, el polietileno biobasado (BioHDPE), es una buena solución para reducir al máximo los problemas derivados de la utilización de recursos fósiles. El BioHDPE ofrece buena resistencia mecánica, alta ductilidad y resistencia al agua. Por otro lado, las cargas naturales se han utilizado desde hace mucho tiempo con el objeto de disminuir el coste del material. En la mayoría de los casos la introducción de estas cargas en porcentajes limitados no afecta de forma significativa a las prestaciones del material compuesto. En este trabajo de investigación, se pretende la obtención de nuevos materiales compuestos respetuosos con el medio ambiente a partir de una matriz polimérica (BioHDPE) con refuerzo de partículas de piña de pino para conseguir reducir los costes del uso del material virgen y, al mismo tiempo, mejorar sus propiedades. Debido a la naturaleza hidrofílica del HDPE, se introduce el copolímero el PE-g-MA con el fin de mejorar la interacción entre las fibras y la matriz. Obtenidas las mezclas en base a la variabilidad porcentual de carga, se realizan estudios de compatibilidad según sus propiedades a base de ensayos experimentales como mecánicos, térmicos, morfológicos, termomecánicos y tratamiento superficial con plasma atmosférico. Los resultados obtenidos permiten validar la obtención de "Wood Plastic Composites" en base a la incorporación de partículas de piña. La utilización de refuerzos de gran abundancia a un coste muy bajo como la piña de pino, ofrece la posibilidad de aumentar el rendimiento del compuesto obtenido. La utilización del compatibilizante PE-g-MA se muestra eficiente a la hora de mejorar las propiedades mecánicas dúctiles de los compuestos. La estabilidad térmica también mejora considerablemente con el uso del compatibilizante incluso con concentraciones mayores de piña. Con respecto al aspecto físico resultante de una pieza inyectada, se han obtenido muestras con un color marrón similar a la de algunas especies de madera natural. Se ha demostrado que la afinidad entre la matriz polimérica apolar y las partículas lignocelulósicas permite un incremento general de prestaciones en el compuesto resultante, lo que supone una notable reducción de coste en el producto final. Por todo ello, se demuestra que la afinidad entre la matriz polimérica apolar y las partículas lignocelulósicas permiten un incremento general de prestaciones en el compuesto. / [CA] A causa de la gran problemàtica que concerneix l'ús de plàstics, s'ha incrementat la consciència social derivada dels problemes mediambientals com la gran quantitat de deixalles plàstiques generades, l'escassetat del petroli, l'augmentant l'empremta de carboni i la contaminació. Com a mesura alternativa, apareix l'ús de material de base biològica, aconseguint reduir amb èxit l'ús de recursos no renovables i disminuir la quantitat d'emprempta de carboni. Dins la industria del plàstic, el polietilè d'alta densitat (HDPE) és un dels plàstics comercials més utilitzats, per la qual cosa, el politilè de base biològica (BioHDPE) és una bona solució per a reduir al màxim els problemes derivats de la utilització de recursos fòssils. El BioHPDE té bona resistencia mecànica, alta ductilitat i resistencia a l'aigua. D'altra banda, les càrregues naturals s'han utilitzat des de fa molt de temps per tal de disminuir el cost del material. En la majoria dels casos, la introducció d'aquestes càrregues en percentatges limitats no afecta de manera significativa a les prestacions del material compost. En aquest treball de'investigació, es pretén obtener nous materials compostos respectuosos amb el medi ambient a partir d'una matriu polimérica (BioHDPE) amb reforç de partícules de pinya de pi per aconseguir reduir els costos de l'ús del material verge i, al mateix temps, millorar les propietats. A causa de la naturalesa hidrofílica del HDPE, s'introduiex el copolímer PE-g-MA per a millorar la interacción entre les fibres i la matriu. Obtingudes les mescles en base a la variabilitat percentual de càrrega, es realitzen estudis de compatibilitat segons les seues propietats a base d'assajos experimentals com els mecànics, tèrmics, morfològics, termomecànics i tractament superficial amb plasma atmosfèric. Els resultats obtinguts permeten validar l'obtenció de "Wood Plastic Composites" en base a la incorporació de particules de pinya. La utilització de reforços de gran abundancia a un cost molt baix com la pinya de pi ofereix la possibilitat d'augmentar el rendiment del compost obtingut. La utilització del compatibilitzant PE-g-MA es mostra eficient a l'hora de millorar les propietats mecàniques dúctils dels compostos. L'estabilitat tèrmica també millora considerablement amb l'ús del compatibilitzant fins i tot amb concentracions més grans de pinya. Pel que fa a l'aspecte físic resultant d'una peça injectada, s'han obtingut mostres amb un color marró semblant a algunes espècies de fusta natural. S'ha demostrat que l'afinitat entre la matriu polimèrica apolar i les partícules lignocel.lulòsiques permet un increment general de prestacions en el compost resultant, fet que suposa una notable reducció de cost en el producte final. Per tot això, es demostra que l'afinitat entre la matriu polimérica apolar i les partícules lignocel.lulòsiques permeten un increment general de prestacions en el compost. / [EN] Due to the great problem that concerns the use of plastics, there has been an increase in social awareness derived from environmental problems based on the large amount of plastic waste generated, the scarcity of oil, the increasing the carbon footprint and the pollution. As an alternative measure, the use of bio-based materials appears, successfully reducing the use of non-renewable resources and reducing the amount of carbon footprint. Within the plastics industry, high-density polyethylene (HDPE) is one of the most widely used commercial plastics. Therefore, bio-based polyethylene (BioHDPE) is a good solution to minimize the problems derived from it of the use of fossil resources. BioHDPE has good mechanical, strength, high ductility and water resistance. On the other hand, natural fillers have been used for a long time in order to reduce the cost of the material. In most cases, the introduction of these loads in limited percentages does not significantly affect the performance of the composite material. In this research work, the aim is to obtain new environmentally friendly composite materials from a polymer matrix (BioHPDE) with reinforcement of pine cone particles to reduce the costs of using the virgin material and improve its properties. Due to the hydrophilic nature of HDPE, the PE-g-MA copolymer is introduced in order to improve the interaction between the fibers and the matrix. Once the mixtures are obtained based on the percentage variability of load, compatibility studies are carried out according to their properties based on experimental tests such as mechanical, thermal, morphological, thermomechanical and surface treatment with atmospheric plasma. The results obtained allow us to validate the production of Wood Plastic Composites based on the incorporation of pine particles. The use of highly abundant reinforcements at a very low cost, such a pine cone, offers the possibility of increasing the performance of the compound obtained. The use of PE-g-MA compatibilizer is shown to be efficient in improving the ductile mechanical properties of the compounds. The thermal stability also improves considerably with the use of the compatibilizer even with higher concentrations of pine. Regarding the resulting physical appearance injected piece, samples have been obtained with a brown color similar to that some species of natural wood. It has been shown that the affinity between the nonpolar polymeric matrix and the lignocellulosic particles allows a general increase in performance in the resulting composite, which represents a notable cost reduction in the final product. For all this, it is demonstrated that the affinity between the nonpolar polymer matrix and the lignocellulosic particles allows a general increase in performance in the composite. / Morcillo Esquerdo, MDC. (2023). Desarrollo y optimización de mezclas de alto rendimiento medioambiental basadas en poliolefinas y cargas de origen natural [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202559

Textiles ultrahochmolekulares Polyethylen (UHMWPE) besitzt, aufgrund seiner außerordentlich hohen Molmasse und einem kristallinen Anteil von mehr als 80 %, exzellente spezifische Reißfestigkeiten sowie sehr gute Beständigkeiten gegenüber biologischen, chemischen und physikalischen Einflüssen, wodurch es sich für den Einsatz in Schutztextilien, als textiler Träger für funktionelle Partikel, zur Faserverstärkung in Kunststoffen für hochbelastbare Bauteile und auch zur Herstellung hochwertiger, technischer Textilmembranen anbietet. Voraussetzung für diese Applikationen ist ein hohes Wechselwirkungsvermögen der Fasergrenzflächen. Im Rahmen dieser Dissertationsschrift wurden systematisch die Möglichkeiten zur Oberflächenaktivierung von textilem UHMWPE mittels Atmosphärendruckplasma (ADP) untersucht und Eigenschafts-Wirkungsbeziehungen verschiedener Einflussparameter, u. a. Plasmaleistung, Elektrodenabstand, Behandlungsintensität, aufgeklärt. Dabei lag ein besonderes Augenmerk auf den textilen Eigenheiten des Materials und der dadurch stark beeinflussten Durchdringung des Plasmas. Entsprechend wurden umfangreiche Messreihen zu chemischen und physikalischen Veränderungen der Faseroberfläche erstellt, um schließlich eine industrielle Nutzbarkeit der ADP-Behandlung ableiten zu können. Hierzu wurden auch zwei weitere Verfahren vergleichend begutachtet und in Kooperation mit dem Leibniz-Institut für Polymerforschung Dresden e.V. eine mögliche Anwendung aktivierter UMHWPE-Garne als Träger für magnetisierbare Nanopartikel betrachtet.

Made available in DSpace on 2017-07-21T20:42:32Z (GMT). No. of bitstreams: 1 Melina Correa Gabriel.pdf: 5915390 bytes, checksum: bae67fca28fd7999823fa6ec6ac98844 (MD5) Previous issue date: 2010-03-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The intention of this exploratory research is to study the modifications provided by high-energy mechanical milling in ultra-high molecular weight polyethylene (UHMWPE) and mixtures of this polymer with polyethylene glycol (PEG). These modifications can be of interest for future processing of UHMWPE. The mechanical milling was performed in an attritor mill, a type of mill that can be used in laboratory as well as in industry. The millings of UHMWPE were performed in different rotation speeds. For mixtures of UHMWPE and PEG, the amounts of PEG were also different. The samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The mechanical milling modified the UHMWPE particles morphology: with milling, the almost rounded shape became flat-like shape. This caused the reduction of apparent density of polymer after milling. The mechanical milling also provided structural changes. With the increasing of the rotation speed,there was the increasing of the monoclinic phase and the decreasing of the orthorhombic, up to 500 rpm. For 600 rpm, the amount of monoclinic phase decreased. In this rotation, the deformation rate probably increased the process temperature, allowing the monoclinic phase to return to its initial structural orthorhombic form. In mixtures of UHMWPE and PEG, after mechanical milling, the particles of PEG were probably reduced and better dispersed in the UHMWPE matrix. Changes in thermal characteristics of polymers also could be noted. The kinetics of UHMWPE crystal growth changed, as well as the behavior of PEG crystallization. Feasibly, dispersed particles of PEG acted as physical barriers against the crystalline phase growth of UHMWPE and the crystallization temperature of PEG decreased, when the UHMWPE and PEG mixtures were milled. / Este trabalho exploratório teve por objetivo estudar as modificações promovidas por moagem de alta energia no de polietileno de ultra-alta massa molar (PEUAMM) e sua mistura com polietileno glicol (PEG), que podem ser de interesse para auxiliar um posterior processamento do PEUAMM. As moagens foram realizadas em um moinho do tipo attritor, um tipo de moinho que pode ser usado tanto em laboratório quanto em escala industrial. Foram variadas as velocidades de rotação na moagem do PEUAMM, além das concentrações de PEG, quando feita a mistura. As amostras foram caracterizadas por microscopia eletrônica de varredura (MEV), microscopia de força atômica (MFA), calorimetria exploratória diferencial (DSC) e difração de raios X. A moagem de alta energia do material modificou a forma das partículas de PEUAMM, passando de arredondadas a flakes, com a evolução do processo de moagem, fazendo com que a densidade aparente do polímero diminuísse muito comparado ao polímero não moído. A moagem também proporcionou mudança estrutural, permitindo a formação de fase monoclínica em detrimento da ortorrômbica. A medida que se aumentou a rotação do moinho até 500 rpm, houve um crescimento da fase monoclínica. Apenas para 600 rpm, a quantidade dessa fase sofreu decréscimo, devido possivelmente ao aumento da frequência de choques e da temperatura de processamento, fazendo com que a estrutura monoclínica retornasse à estrutura ortorrômbica original. Na mistura de PEUAMM com PEG, a moagem provavelmente permitiu redução das partículas e a melhor dispersão de PEG na matriz de PEUAMM. Também se observaram mudanças nas características térmicas dos polímeros na mistura após moagem. Ocorreu mudança na cinética de crescimento dos cristais de PEUAMM e mudança no comportamento de cristalização do PEG, comportamento este que não ocorreu para o PEUAMM moído ou para a mistura de PEUAMM com PEG antes da moagem. Possivelmente, as partículas dispersas de PEG atuaram como barreiras ao crescimento da fase cristalina do PEUAMM e houve diminuição da temperatura de cristalização do PEG, na mistura com PEUAMM após moagem.