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Thin film bilayers and blends composed of polymers and nanoparticles are increasingly important for technological applications that range from space survivable coatings to novel drug delivery systems. Dewetting or spontaneous hole formation in amorphous polymer films and phase separation in multicomponent polymer films can hinder the stability of these systems at elevated temperatures. Hence, fundamental understanding of dewetting and phase separation in polymer/nanoparticle bilayer and blend films is crucial for controlling transport and thermomechanical properties and surface morphologies of these systems. This dissertation provides studies on morphological evolution driven by phase separation and/or dewetting in model polymer/nanoparticle thin film bilayers and blends at elevated temperatures. Morphological evolution in dewetting bilayers of poly(t-butyl acrylate) (PtBA) or polystyrene (PS) and a polyhedral oligomeric silsesquioxane (POSS), trisilanolphenyl-POSS (TPP) is explored at elevated temperatures. The results demonstrate unique dewetting morphologies in both PtBA/TPP and PS/TPP bilayers that are significantly different from those typically observed in dewetting polymer/polymer bilayers. Upon annealing the PtBA/TPP bilayers at 95°C, a two-step dewetting process is observed. PtBA immediately diffuses into the upper TPP layer leading to hole formation and subsequently the holes merge to form interconnected rim structures in the upper TPP layer. Dewetting of both the TPP and PtBA layers at longer annealing times leads to the evolution of scattered holes containing TPP-rich, fractal aggregates. The fractal dimensions of the TPP-rich, fractal aggregates are ~2.2 suggesting fractal pattern formation via cluster-cluster aggregation. Dewetting in PS/TPP bilayers also proceeds via a two-step process; however, the observed dewetting morphologies are dramatically different from those observed in PtBA/TPP bilayers. Cracks immediately form in the upper TPP layer during annealing of PS/TPP bilayers at 200°C. With increasing annealing times, the cracks in the TPP layer act as nucleation sites for dewetting and aggregation of the TPP layer and subsequent dewetting of the underlying PS layer. Complete dewetting of both the TPP and PS layers results in the formation of TPP encapsulated PS droplets. Phase separation in PtBA/TPP thin film blends is investigated as functions of annealing temperature and time. The PtBA/TPP thin film blend system exhibits an upper critical solution temperature (LCST) phase diagram with a critical composition and temperature of 60 wt% PtBA and ~70°C, respectively. Spinodal decomposition (SD) is observed for 60 wt% PtBA blend films and off-critical SD is seen for 58 and 62 wt% PtBA blend films. The temporal evolution of SD in 60 wt% PtBA blend films is also explored. Power law scaling for the characteristic wavevector with time (q ~ t^n with n = -1/4 to -1/3) during the early stages of phase separation yields to domain pinning at the later stages for films annealed at 75, 85, and 95°C. In contrast, domain growth is instantly pinned for films annealed at 105°C. Our work provides an important first step towards understanding how nanoparticles affect polymer thin film stability and this knowledge may be utilized to fabricate surfaces with tunable morphologies via controlled dewetting and/or phase separation. / Ph. D.

Poly (caprolactone) (PCL) has been widely studied as a model system for investigating polymer crystallization. In this thesis, PCL crystallization along with other phase transitions in PCL-based polymer blends are studied as Langmuir films at the air/water (A/W) interface. In order to understand the phase behavior of PCL-based blends, surface pressure induced crystallization of PCL in single-component Langmuir monolayers was first studied by Brewster angle microscopy (BAM). PCL crystals observed during film compression exhibit butterfly-shapes. During expansion of the crystallized film, polymer chains detach from the crystals and diffuse back into the monolayer as the crystals "melt". Electron diffraction on Langmuir-Schaefer films suggests that the lamellar crystals are oriented with the chain axes perpendicular to the substrate surface, while atomic force microscopy (AFM) reveals a crystal thickness of ~ 7.6 nm. In addition, the competition between lower segmental mobility and a greater degree of undercooling with increasing molar mass produces a maximum average growth rate at intermediate molar mass. PCL was blended with poly(t-butyl acrylate) (PtBA) to study the influence of PtBA on the morphologies of PCL crystals grown in monolayers. For PCL-rich blends, BAM studies reveal dendritic morphologies of PCL crystals. The thicknesses of the PCL dendrites are ~ 7-8 nm. BAM studies during isobaric area relaxation experiments at different surface pressure reveal morphological transitions from highly branched dendrites, to six-arm dendrites, four-arm dendrites, seaweedlike crystals, and distorted rectangular crystals. In contrast, PCL crystallization is suppressed in PtBA-rich blend films. For immiscible blends of PCL and polystyrene (PS) with intermediate molar masses as Langmuir films, the surface concentration of PCL is the only factor influencing surface pressure below the collapse transition. For PS-rich blends, both BAM and AFM studies reveal that PS nanoparticle aggregates formed at very low surface pressure form networks during film compression. For PCL-rich blends, small PS aggregates serve as heterogeneous nucleation centers for the growth of PCL crystals. During film expansion, BAM images show a gradual change in the surface morphology from highly continuous networklike structures (PS-rich blends) to broken ringlike structures (intermediate composition) to small discontinuous aggregates (PCL-rich blends). / Ph. D.

Conventional studies of ionomers have focused on ionomers bearing monovalent carboxylate or sulfonate pendant ions. There are relatively fewer studies on ionomers containing multivalent pendant ions, such as divalent phosphonate. In this dissertation, poly(ethylene terephthalate) (PET) and polystyrene ionomers with divalent phosphonate pendant ions have been synthesized, and the influence of divalent phosphonate pendant ions on the structure-morphology-property relationship has been compared to the ionomers with monovalent sulfonate pendant ions. The phosphonate groups generated a stronger physically crosslinked network in phosphonated ionomers as compared to sulfonated analogues. Higher plateau modulus, longer relaxation time, and significantly higher zero-shear viscosity were noted for phosphonated ionomers by a dynamic melt rheology study. Compared to the ionic aggregates generated from sulfonate groups, larger ionic aggregates with associated phosphonate groups have been observed. Furthermore, phosphonated ionomers displayed significantly higher glass transition temperatures than sulfonated ionomers. Ionomers have proven to be attractive, interfacially active compatibilizers for a number of polymer blend systems because of specific interactions that may develop between the ionic groups and complementary functional groups on other polar polymers within the blends. The successful compatibilization of polyester/polyamide blends (prepared by solution mixing and melt blending methods) using phosphonated PET ionomers as a minor-component compatibilizer has been demonstrated. The phase-separated polyamide domain dimension decreased with increasing mol % phosphonated monomers and this decrease was attributed to the specific interactions between the ionic phosphonate groups on the polyester ionomer and the amide linkages of polyamide. More importantly, the divalent phosphonate pendant ions are more effective at compatibilizing polyester/polyamide blends in comparison to the monovalent sulfonate pendant ions. Phosphonated PET ionomer-compatibilized polyester/polyamide blends required 6 times fewer ionic monomers to achieve domain dimension < 1 μm as compared to sulfonated PET-containing blends. Deep eutectic solvents (DES) have been reported to be the next generation solvents due to the superior biocompatibility, biodegradability, and sustainability as compared to ionic liquids. Two types of deep eutectic solvents, choline chloride : malic acid (ChCl:MA) and L-arginine : levulinic acid (Arg:LA), have been demonstrated as effective plasticizers for poly(vinyl alcohol) (PVOH) films. The plasticization effects on the properties of PVOH films were evidenced by lower crystallizability and improved film ductility. In addition, ChCl:MA deep eutectic solvent was more effective in plasticizing PVOH as compared to propylene glycol, one of the most widely studied alcohol-type plasticizers. From an applied perspective, DES-plasticized PVOH film is a promising candidate in the packaging market of heath-related products. / Doctor of Philosophy / Non-covalent interactions play an important role on the structure-morphology-property relationship of polymeric materials. Divalent phosphonate pendant ions provide interesting effects on the properties of ionomer and polymer blends as compared to the monovalent sulfonate pendant ions. Ionomers containing phosphonate pendant ions exhibit a significantly stronger physically crosslinked network as compared to sulfonated ionomers. Compared to monovalent sulfonate groups, the divalent phosphonate groups are more effective at compatibilizing polymer blends. Furthermore, the compatibilized poly(ethylene terephthalate)-based blends exhibit improved optical and oxygen barrier properties compared to the base blend without compatibilizer, signifying potential benefits in packaging industry. Poly(vinyl alcohol) is one of the most widely used packaging materials for food, medicine, detergent, etc. The incorporation of deep eutectic solvents as plasticizers significantly improved film ductility. In addition, the plasticization effect for choline chloride-based deep eutectic solvent is more profound than one of the most widely studied alcohol-type plasticizers, propylene glycol. The effective plasticization of poly(vinyl alcohol) using deep eutectic solvents confirmed the potential for future applications in the packaging market of health-related product.

Physical aging measurements were performed on various polymeric glasses with the overriding goal of developing a better molecular picture of the nonequilibrium glassy state. To this end, aging-induced changes in mechanical properties and in the thermodynamic state (volume and enthalpy) were assessed for two different miscible polymer blends as a function of both composition and aging temperature. This investigation considered the physical aging behavior of blends containing atactic polystyrene (a-PS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) as well as mixtures of poly(methyl methacrylate) (PMMA) and poly(styrene-co-acrylonitrile) (SAN). Substantial attractive chemical interactions are characteristic of a-PS/PPO blends but are absent in PMMA/SAN blends. The distinct nature of interactions for these two blends resulted in differences in the compositional dependence of secondary relaxation intensity, segmental cooperativity which dictates glass formation kinetics, and density (prior to aging). The variation of volume relaxation rate with aging temperature and composition was interpreted based upon these characteristics for the two systems. In addition, a general relationship was uncovered which linked structural relaxation rates for amorphous polymers to their respective segmental relaxation characteristics (glass transition cooperativity or fragility), which in turn are well understood from a molecular standpoint. This work, therefore, established a basis for comprehending glassy state volume and enthalpy relaxation rates based upon molecular characteristics. Developing an understanding of the connection between the evolving thermodynamic state and mechanical property changes fared less well. The fact that the thermodynamic and mechanical properties can have very different relaxation time responses governing their changes in the nonequilibrium glassy state was clearly evident in an extensive study of the physical aging characteristics of an amorphous polyimide material. For some materials, interpretation of mechanical aging behavior was obscured by thermorheological complexity arising due to overlap of a secondary relaxation with the main chain softening dispersion. / Ph. D.

This dissertation discusses results of crystallization kinetic, morphology and scattering studies on miscible semi crystalline blends of poly(pivalolactone)/ poly(vinylidene fluoride)(pPVLIPVF₂) and poly(pivalolactone)/poly(vinylidene fluoride <i>co</i>- tetrafluoroethylene)(95-5) (PPVL/P(VF2-TFE)(95-5)) prepared by solution blending. The spherulitic growth rates of the α-phase PPVL from miscible blends with PVF₂ or P(VF₂- TFE)(95-5) were measured by polarized optical microscopy as a function of blend composition and isothermal crystallization temperature, Tx, between 160°C and 215.5°C. The PPVL weight fraction in the blends ranged from 100 to 10 wt%. Using the Lauritzen-Hoffman kinetic theory of polymer crystal growth, the equilibrium melting temperatures of the α-phase PPVL in both the PPVL/PVF₂ and the PPVL/P(VF₂-TFE)(95-5) blends have been determined, for the first time, directly from the spherulitic growth rate data. Analysis of the composition dependence of the nucleation constant, Kg suggests that the α-phase PPVL crystal/melt lateral interface free energy, Ï , in the blends decreases markedly with increasing PVF₂ or P(VF₂-TFE)(95-5) concentration. / Ph. D.

El proceso de inyección es un proceso de conformado de los materiales poliméricos termoplásticos que, en la actualidad, presenta una notable importancia económica y tecnológica, y cuyo estudio ha supuesto multitud de investigaciones relacionadas con la determinación de condiciones óptimas de proceso. Por otra parte, los materiales poliméricos reciclados, resultado del desecho de productos que han finalizado su vida útil, representan una importante fuente de materias primas que puede ser reaprovechadas para la obtención de productos con calidades aceptables y con costes inferiores a los convencionales. Aglutinando los dos aspectos anteriores, la presente tesis tiene como objetivo el estudio y determinación de las condiciones de proceso mediante moldeo por inyección de blends de ABS/PC obtenidos a partir de materiales reciclados, proponiendo un modelo de procesabüidad de material que minimice la defectología de la pieza en condiciones de máxima estabilidad de variables de proceso. Para la realización de este estudio se han considerado mezclas de ABS con contenidos bajos de PC (0 - 5 -10) y se han comprobado las diferencias que dichos contenidos provocan sobre el comportamiento del material. Este estudio se ha estructurado en dos etapas diferenciadas, cuya secuenciación ha sido necesaria para su desarrollo. La primera fase está dedicada al estudio y modelización del material, con la perspectiva de la determinación de las características y parámetros necesarios para su procesado. A este respecto se ha desarrollado un modelo de comportamiento reológico de las diferentes mezclas del material, evaluable a partir de ensayos simples de laboratorio y cuyo resultado se ha adoptado como parámetro de entrada para las simulaciones de inyección. Asimismo, se han verificado las características del comportamiento p-v-T de las mezclas, constatando la mínima influencia del PC sobre el ABS puro. La segunda fase lleva a cabo el estudio y modelización del proceso de inyección, consideran / Reig Pérez, MJ. (2004). Estudio y modelización de las condiciones de proceso en el moldeo por inyección de blends ABS/PC procedentes de materiales reciclados [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/56766

Tesis por compendio / "Development of polylactic acid (PLA)-derived formulations by plasticization and additives from renewable resources" The main objective of this doctoral thesis is the study, development and characterization of biodegradable or biocompatible materials from poly(lactic acid) (PLA) with improved properties for uses in several sectors such as food packaging, medical sector, etc. In order to modify the ductility and the stiffness of PLA, with the subsequent effects on its potential uses in different sectors, different fillers and/or additives were incorporated to PLA formulations by extrusion. Several plasticizers derived from vegetable oils and fatty acids were used; particularly, an epoxidized plasticizer derived from stearic acid (octyl epoxy stearate - OES) and a maleinized linseed oil - MLO were used. Another strategy that has been used in this research has focused on the development of binary blends with other polymers with increased ductility such as polycaprolactone (PCL) and thermoplastic starch (TPS). Finally, incorporation of several biocompatible/resorbable fillers derived from calcium orthophosphate (Ca3(PO4)2) such as ß-tricalcium phosphate (ß-TCP) and hydroxyapatite (HA), was carried out to widen the potential of these PLA-based materials in medical applications. / "Desarrollo de formulaciones derivadas de ácido poliláctico (PLA), mediante plastificación e incorporación de aditivos de origen natural" El objetivo principal de esta tesis doctoral es el estudio, desarrollo y caracterización de materiales biodegradables o biocompatibles de ácido poliláctico (PLA) con propiedades mejoradas para su aplicación en diversos sectores como el envasado de alimentos, sector médico, etc. Para modificar la ductilidad o rigidez del PLA y con ello su aptitud en los distintos campos, se lleva a cabo un estudio de la incorporación de diferentes cargas o aditivos, mediante mezclado por extrusión. Se han utilizado plastificantes derivados de aceites vegetales y ácidos grasos; en particular, un plastificante epoxidado derivado del ácido esteárico (epoxi estearato de octilo - OES) y un derivado maleinizado de aceite de linaza - MLO. Otra de las estrategias que se han abordado se ha centrado en el desarrollo de mezclas binarias con otros biopolímeros con mayor ductilidad como la policaprolactona (PCL) y el almidón termoplástico (TPS). Finalmente, se ha llevado a cabo la incorporación de cargas biocompatibles tipo ortofosfato cálcico (Ca3(PO4)2) como el ß-fosfato tricálcico (ß-TCP) y la hidroxiapatita (HA) para ampliar el potencial de estos materiales basados en PLA en el sector médico. / "Desenvolupament de formulacions derivades d'àcid polilàctic (PLA), mitjançant plastificació i incorporació d'additius d'origen natural" L'objectiu principal d'aquesta tesi doctoral és l'estudi, desenvolupament i caracterització de materials biodegradables i biocompatibles d'àcid polilàctic (PLA) amb propietats millorades per a la seua aplicació en diversos sectors com ara l'envasat d'aliments, sector mèdic, etc. Per tal de modificar la ductilitat o rigidesa del PLA, i amb això, la seua aptitud en els esmentats camps, s'ha fet un estudi de la incorporació de diferents càrregues o additius, mitjançant mesclat per extrusió. S'han utilitzat plastificants derivats d'olis vegetals i àcids grassos; en particular, un plastificant epoxidat derivat de l'àcid esteàric (epoxi estearat d'octil - OES) i un derivat maleinitzat d'oli llinós - MLO. Una altra estratègia que s'ha seguit s'ha centrat en el desenvolupament de mescles binàries amb altres polímers amb major ductilitat com ara la policaprolactona (PCL) i el midó termoplàstic (TPS). Finalment, s'ha dut a terme la incorporació de càrregues biocompatibles de tipus ortofosfat càlcic (Ca3(PO4)2) com ara el ß-fosfat tricàlcic (ß-TCP) i la hidroxiapatita (HA) per tal d'ampliar el potencial d'aquests materials basats en PLA al sector mèdic. / Ferri Azor, JM. (2017). Desarrollo de formulaciones derivadas de ácido poliláctico (PLA), mediante plastificación e incorporación de aditivos de origen natural [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86166 / Premios Extraordinarios de tesis doctorales / Compendio

RESUMEN. "Reducción de la fragilidad de formulaciones industriales de ácido poliláctico - PLA mediante el empleo de técnicas de mezclado y compatibilización" En los últimos años, se ha producido un incremento de la sensibilidad por el medio ambiente. Con ello, muchas investigaciones se han dirigido hacia el desarrollo de nuevos materiales más respetuosos con el medio ambiente. En el campo de la tecnología de polímeros, el empleo de biopoliésteres poco a poco está invadiendo los sectores industriales. Entre estos poliésteres, el ácido poliláctico (PLA), que puede obtenerse a partir de recursos renovables como el almidón, ha ido ganando relevancia al mismo tiempo que su precio ha ido disminuyendo. Actualmente el PLA es un biopolímero de gran importancia en sectores como automoción, construcción, sector médico, impresión 3D, etc. entre otros. El PLA presenta excelentes propiedades mecánicas y buena estabilidad térmica. Además, ofrece una ventana de procesado bastante amplia que permite la fabricación de piezas y componentes evitando la degradación térmica de éste. No obstante, el PLA es un polímero de alta cristalinidad y ello repercute en sus propiedades dúctiles. Este se caracteriza por un bajo alargamiento a la rotura, baja tenacidad y, en consecuencia, elevada fragilidad. Esta tesis doctoral se centra en la mejora de las propiedades dúctiles y reducción de la fragilidad intrínseca del PLA para ampliar, todavía más, sus aplicaciones industriales. De los diferentes planteamientos: plastificación, copolimerización, extrusión reactiva y mezclado, esta tesis doctoral se centra en la reducción de la fragilidad mediante la obtención de mezclas ternarias con otros biopoliésteres con el fin de obtener formulaciones altamente respetuosas con el medio ambiente y un conjunto de propiedades equilibradas. Para ello se plantea la hipótesis de emplear un biopoliéster que mantenga las propiedades mecánicas resistentes en valores altos. En este caso, se ha trabajado con poli(3-hidroxibuturato) - (PHB), obtenido por fermentación bacteriana. La otra hipótesis de trabajo, se centra en el empleo de diversos biopoliésteres flexibles que aporten buena resistencia al impacto, aumentando, de esta manera, la tenacidad de las formulaciones industriales. Con este fin, en esta tesis se trabaja con diversos biopoliésteres flexibles como la poli(¿-caprolactona) - (PCL), poli(butilén succinato) - (PBS) y un copoliéster, el poli(butilén succinado-co-adipato) - (PBSA). Considerando la importancia que adquieren los fenómenos de miscibilidad en las propiedades finales de mezclas de polímeros, se plantea la utilización de una serie de agentes compatibilizantes derivados de recursos naturales renovables. En particular, se trabaja con aceites vegetales modificados (epoxidados, malenizados y acrilados). Así, dada la reactividad de los grupos epoxi, anhídrido maleico y ácido acrílico con los grupos hidroxilo terminales presentes en las cadenas de los diferentes biopoliésteres, se plantea la hipótesis de mejora de la miscibilidad/interacción entre los diferentes polímeros de las mezclas ternarias mediante el empleo de aceite de soja epoxidado, maleinizado y acrilado (ESO, MSBO y AESO respectivamente). De forma global, los resultados obtenidos en esta tesis doctoral, permiten ampliar el campo de utilización del PLA a través de mezclas ternarias con PHB y PCL o bien con PHB y PBS o PBSA. Las formulaciones desarrolladas en este trabajo de investigación mejoran notablemente la tenacidad del PLA, aspecto que permite reducir de forma significativa su fragilidad intrínseca. / RESUM. "Reducció de la fragilitat intrínsica de formulacions industrials d'àcid polilàctic - PLA mitjançant la utilització de tècniques de mesclat i compatibil·lització" En els últims anys, s'ha produït un increment de la sensibilitat pel medi ambient. Amb aquest, moltes investigacions s'han dirigit cap al desenvolupament de nous materials més respectuosos amb el medi ambient. En el camp de la tecnologia de materials polimèrics, la utilització de biopolièsters poc a poc està envaint els sectors industrials. Entre tots aquest biopolièsters, l'àcid polilàctic (PLA), que pot obtenir-se a partir de recursos renovables com ara el midó, ha anat guanyant rellevància al mateix temps que el seu preu ha anat disminuint. Actualment, el PLA és un biopolímer de gran importància en sectors com l'automoció, construcció, sector mèdic, impressió 3D, etc. entre d'altres. El PLA presenta excel·lents propietats mecàniques i una bona estabilitat tèrmica. A més a més, ofereix una finestra de processat prou ampla que permet la fabricació de peces i components evitant la degradació tèrmica d'aquest. No obstant això, el PLA és un polímer d'alta cristal·linitat i això repercuteix en les seues propietats dúctils. Aquest es caracteritza per un baix allargament a la ruptura, baixa tenacitat i, en conseqüència, elevada fragilitat. Aquesta tesi doctoral es centra en la millora de les propietats dúctils i la reducció de la fragilitat intrínseca del PLA per tal d'ampliar, encara més, les seues aplicacions industrials. Dels diferents plantejaments possibles: plastificació, copolimerització, extrusió reactiva i mesclat, aquesta tesi doctoral es centra en la reducció de la fragilitat mitjançant l'obtenció de mescles ternàries amb d'altres biopolièsters amb la finalitat d'obtenir formulacions altament respectuoses amb el medi ambient i un conjunt de propietats equilibrades. Per a aconseguir això, es planteja la hipòtesi d'utilitzar un biopolièster que mantinga les propietats mecàniques resistents en valors elevats. En aquest cas, s'ha treballat amb poli(3-hidroxibutirat) - (PHB), obtingut per fermentació bacteriana. L'altra hipòtesi de treball, es centra en la utilització de diversos biopolièsters flexibles que siguen capaços d'aportar una bona resistència a l'impacte, augmentant, d'aquesta manera, la tenacitat de les formulacions industrials. Amb aquesta finalitat, en aquesta tesi es treballa amb diversos biopolièsters flexibles com ara la poli(e-caprolactona) - (PCL), el poli(butilé succinat) - (PBS) i un copolièster, el poli(butilé succinat-co-adipat) - (PBSA). Considerant la importància que adquireixen els fenòmens de miscibilitat en les propietats finals de les mescles de polímers, es planteja la utilització d'una sèrie d'agents compatibilitzants derivats de recursos naturals renovables. En particular, es treballa amb olis vegetals modificats (epoxidats, maleinitzats i acril·lats). Així, donada la reactivitat dels grups epòxid, anhídrid maleic i àcid acríl·lic amb els grups hidroxil terminals que presenten les cadenes dels diferents biopolièsters, es planteja la hipòtesi de la millora de la miscibilitat/interacció entre els diferents polímers de les mescles ternàries mitjançant la utilització d'oli de soja epoxidat, maleinitzat i acril·lat (ESO, MSO i AESO respectivament). De forma global, els resultats obtinguts amb aquesta tesi doctoral, permeten ampliar el camp d'utilització del PLA a través de mescles ternàries amb PHB i PCL o bé, amb PHB i PBS ò PBSA. Les formulacions desenvolupades en aquest treball d'investigació milloren notablement la tenacitat del PLA, aspecte que permet reduir de forma significativa la seua fragilitat intrínseca. / SUMMARY. "Reduction of the intrinsic fragility of industrial poly(lactic acid) - PLA formulations by using blending and compatibilization techniques" In the last years, a remarkable increase in the sensitiveness about environment has been detected. As a consequence, many research works have been focused on the development on new environmentally friendly materials. This interest has been particularly remarked in the field of polymer technology, in which, the increasing use of biopolyesters is slowly invading several industrial sectors. Among these polyesters, polylactic acid (PLA), which can be obtained from renewable resources such as starch, has been gaining relevance at the same time that its price is continuously decreasing. Currently PLA is a biopolymer of great relevance in technological sectors such as automotive, construction and building, medical sector, 3D printing, and so on, among others. PLA shows excellent mechanical properties and good thermal stability. In addition, it offers a wide processing window that allows the manufacture of parts and components avoiding or minimizing its thermal degradation. However, PLA is a polymer with high crystallinity and this has a negative effect on its ductile properties. This is characterized by low elongation at break, low tenacity and, consequently, high fragility. This doctoral thesis focuses on the improvement of the ductile properties and reduction of the intrinsic brittleness of PLA to expand, even more, its industrial applications. Although different approaches are being investigated: plasticizing, copolymerization, reactive extrusion and blending, this doctoral thesis focuses on the reduction of brittleness by obtaining ternary blends with other biopolyesters in order to obtain highly environmentally friendly formulations and a set of balanced properties. For this, the hypothesis of using a biopolyester that maintains the resistant mechanical properties in high values is proposed. In this case, we have worked with poly (3-hydroxybuturate) - (PHB), obtained by bacterial fermentation. The other working hypothesis focuses on the use of various flexible biopolyesters that could provide good impact resistance, thus increasing the tenacity of industrial formulations. To this end, various flexible bio-polyesters such as poly (¿-caprolactone) - (PCL), poly (butylene succinate) - (PBS) and a copolyester, poly (butylene succinate-co-adipate) - (PBSA) are used. Considering the relevance of miscibility phenomena on final properties of polymer blends, the use of a series of compatibilizing agents derived from renewable natural resources is considered. In particular, this research reports the use of modified vegetable oils (epoxidized and maleinized). Thus, considering the reactivity between the epoxy, maleic anhydride and acrylic acid groups with the terminal hydroxyl groups present in the polymer chains of the different biopolyesters, it is possible to hypothesize the improvement of the miscibility/interaction between the different polymers in ternary blends by using epoxidized, maleinized and acrylated soybean oil (ESO, MSO and AESO respectively). Overall, the results obtained in this doctoral thesis, allow to expand the potential use of the PLA through ternary blends with PHB and PCL or with PHB and PBS or PBSA. The formulations developed in this research work significantly improve the tenacity of the PLA, which allows to significantly reduce its intrinsic brittleness. / García Campo, MJ. (2018). Reducción de la fragilidad de formulaciones industriales de ácido poliláctico - PLA mediante el empleo de técnicas de mezclado y compatibilización [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/114022