Diversos métodos de ensaios não-destrutivos (Ultrasom, Radiografia, Termografia e Shearografia) foram empregados na inspeção de peças laminadas estruturais compósitas sólidas de matriz polimérica manufaturadas pela indústria aeronáutica. Concluiu-se que Ultrasom pulso-eco convencional de contato foi a técnica mais abrangente na indicação de descontinuidades (danos/defeitos de manufatura) considerando-se peças planas e curvas, não obstante tenha falhado na detecção de trincas longas e bem definidas localizada na alma de componentes co-curados. Radiografia convencional por filmes exibiu um potencial interessante como método alternativo, ou complementar ao de Ultrasom. Termografia infravermelha foi a técnica mais veloz na indicação de descontinuidades, sendo uma valiosa alternativa para um mapeamento rápido em inspeções preliminares seguidas pela aplicação de técnicas complementares. Shearografia realizada com equipamento da empresa Photonita detectou inclusões em peça plana compósita, porém a interpretação dos resultados obtidos em geometrias mais complexas se mostrou duvidosa. O uso de equipamento shearográfico da empresa Dantec indicou posições em regiões curvas que podem estar associadas à presença de defeitos/danos locais, porém uma confirmação cabal desta relação não foi efetivada. Evidências visuais da profusa presença de danos/defeitos de manufatura, além da existência de detalhes construtivos nas peças compósitas mais complexas, sugerem que estas descontinuidades podem ter sensibilizado, em maior ou menor extensão, os equipamentos END, juntamente com a eventual presença de delaminações/falhas de adesão nas respectivas peças avaliadas. / Several nondestructive methods (Ultrasonics, Radiography, Thermography and Shearography) were employed for inspection of structural polymer matrix composite laminated parts manufactured by aircraft industry. Is has been concluded that conventional pulse-echo contact Ultrasonics was the most comprehensive technique to indicate discontinuities (manufacture damages/defects) in flat and curved parts, although it has failed to detect long and well-defined cracks in co-cured components. Conventional film radiography exhibited good potential as alternative or complementary method to Ultrasonics. Infrared thermography was the fastest technique to indicate discontinuities, so that it is a valuable option for rapid mapping in preliminary inspection followed by the application of complementary techniques. Sherography by means of Photonita equipment detected inclusions in flat panels, but the interpretation of results from pieces with more complex geometries was dubious. A shearographic of the Dantec device indicated positions in curved regions which might possibly be associated to the presence of damages/defects, however this relationship could not be definitively established. Visual evidences of the profuse existence of manufacture damages/defects, besides constructive details in more complex composite parts, suggest that theses discontinuities might have affected to some extent the NDT equipments, along with the eventual presence of delaminations/lack of adhesion on the respective evaluated parts.

This diploma thesis is focused on monitoring of mechanical response of long-fiber reinforced polymer composite. Main part of this thesis was preparation of long-fiber reinforced composite specimens, on which matrix was reinforced by commercially sized glass fibers. For comparison of properties were prepared specimens reinforced by unsized glass fibers. Apart from preparing specimens reinforced by long glass fibers were prepared specimens contains long carbon fibers. For evaluation of mechanical response of the prepared composite specimen were used flexural test and short beam shear test. Mechanical response was evaluated with universal testing machine ZWICK Z010 and data were processed in OriginPro 8 program. Thanks to evaluation of the mechanical response of the prepared specimens was assessed adhesion to fiber-matrix interface. By examining the mechanical response or adhesion can be assessed efficiency of commercial fiber surface treatment and so standardize measurement to compare other options of surface treatments.

Diploma work deals with the proposal of single purpose maschine for the maschining of test dumb bells of polymer composite material filled with glass fibre. The purpose of this maschine is to process the test parts with dimensions of 3x5 mm up to 4x8 mm. The maschined part can have a profile with a maximum cross section 20 mm, or 20x20 mm. Based on the given parametres I prepared the proposal of the engineering process the overall set up including the drive force, its own feeding of the object, cooling and waste removal.

Diploma thesis is aimed at deposition of thin films on glass fibers using plasma-enhanced chemical vapor deposition from tetravinylsilane as a monomer. Such surface modified glass fibers were used as reinforcements for fabrication of polymer composites with unsaturated polyester resin as a matrix. Chemical and optical properties of prepared thin films were characterized using infared spectroscopy and spectroscopic ellipsometry. An influence of deposited thin films on the shear strength of composite material was observed using short-beam shear test.

Metal-organic frameworks (MOFs) are an emerging class of materials exhibiting desirable properties and functionalities for a variety of applications, including catalysis, molecular separation, gas storage, and mechanical reinforcement. However, the majority of MOFs exist as particulate powders, limiting their transportability and applicability in practical fields. Polymers, on the other hand, are one of the most widely used materials in the world owing to their facile processability and low production cost. Combining MOFs and polymers to form MOF-polymer composites can potentially maintain the merits of both materials while overcoming drawbacks of each individual component. Specifically, MOFs are promising candidates as mechanical reinforcers for polymers because of their low density, high specific modulus, and controllable dimensions. Herein, we aim to provide a comprehensive investigation into the chemistry and mechanical properties of MOF-polymer composites. Various governing parameters, including particle aspect ratio (AR), MOF-particle interface, and intrinsic mechanical properties of MOFs, were thoroughly studied to construct an optimal pathway for fabricating mechanically reinforced MOF-polymer composites. Chapter 1 presents an introduction to MOFs, polymer composites, and mechanical properties and characterizations of polymeric materials. It serves as a foundation of this dissertation and outlines essential concepts for the scientific background. The primary factors that impact the mechanical properties of polymer composite are highlighted, leading to the following three research chapters. Comprehensive background on various characterization techniques that aim at mechanical properties is covered in detail. Chapter 2 focuses on the role of MOF AR on the mechanical properties of MOF-polymer composites. PCN-222, a Zr-MOF with porphyrin linkers, was synthesized with AR ranging from 3.4 to 54. The crystallinity and chemical structure of the MOFs remained consistent for different ARs, ensuring that the AR was the only variable in determining the mechanical reinforcement. Fabricated through the doctor-blade technique, the MOF-PMMA composite films showed homogeneous MOF distribution and alignment. Tensile tests revealed that Young's modulus of the composites increased with MOF AR, exhibiting a good agreement with a modified Halpin-Tsai model. Both storage and loss moduli were also enhanced following increased MOF AR. In addition, the thermal stability was also improved with the addition of MOF particles. In Chapter 3, the authors extend the understanding of mechanical properties of MOF-polymer composites to the interfacial properties between the two materials. Pristine MOFs often lack strong interactions with a polymer matrix due to the difference in chemical/physical properties. The authors developed a three-step synthetic route to grow PMMA on the surface of PCN-222. Owing to an efficient surface-initiated polymerization technique, the PMMA was successfully grafted with high molecular weight and grafting density. The molecular weight of PMMA could be controlled by simply varying polymerization time. The PMMA-grafted PCN-222 was manufactured along with PMMA matrix to form composite films. Mechanical analysis proved that the mechanical reinforcement was improved with increasing grafted molecular weight. Chapter 4 presents an experimental approach to unveil the structure-mechanical property of MOF single crystals, which provides insights on designing MOFs with desired mechanical strength. Zeolitic imidazolate frameworks (ZIFs), a subdivision of MOFs, were chosen as the template owing to their facile synthesis, structural diversity, and high crystallinity. Two types of micron-sized ZIFs, ZIF-8 with Zn2+ node and ZIF-67 with Co2+ node, were synthesized to compare the effect of metal-linker bond. Moreover, the linker composition was varied to examine the difference in crystal structure and defect level. The mechanical properties of these ZIF samples were revealed by nanoindentation on single particles. Overall, the stronger metal-linker bond and high crystallinity were able to yield the highest elastic modulus and hardness. Finally, Chapter 5 offers a comprehensive review on polymer-grafted MOF particles regarding the synthesis and applications associated with surface-anchored polymers. Various polymerization techniques were summarized, and their adjustment and limitations with respect to MOFs were highlighted. The novel and unique applications arisen from polymer-grafted MOFs and Mixed Matrix Membranes were thoroughly discussed. / Doctor of Philosophy / Polymer composites, a combination of polymer matrix and particle fillers, have shown great applicability in nearly every aspect of our daily lives. For example, rubber tires, composed of synthetic polymeric rubber and inorganic particle fillers (e.g., carbon black and glass fiber), have been a great booster for modern society owing to their durability and mechanical strength. Aircraft are also made of roughly 50% composite materials, because of their lightweight and high mechanical strength. Herein, we present a novel type of polymer composite using metal-organic frameworks (MOFs) as mechanical reinforcers. Thanks to the low density, high modulus, and tunable geometry, MOFs can be ideal candidates for mechanically reinforced polymer composites. In this dissertation, several fundamental parameters that impact the mechanical properties of MOF-polymer composites are discussed. The intent of this work is to provide mechanistic insights on the development of outstanding lightweight composites with efficient mechanical reinforcement.

Conductive polymer composite sensors have shown great potential in identifying gaseous analytes. To more thoroughly understand the physical and chemical mechanism of this type of sensors, a model was developed by combining two sub-models: a conductivity model and a thermodynamic model, which gives a relationship between the vapor concentration of analyte(s) and the change of the sensor signals. In this work, 64 chemiresistors representing eight different carbon concentrations (8–60 vol.% carbon) were constructed by depositing thin films of a carbon black–polyisobutylene composite onto concentric spiral platinum electrodes on a silicon chip. The responses of the sensors were measured in dry air and at various vapor pressures of toluene and trichloroethylene. Three parameters in the conductivity model were determined by fitting the experimental data. It was shown that by applying this model, the sensor responses can be predicted if the vapor pressure is known; furthermore the vapor concentration can be estimated based on the sensor responses. This model will guide the improvement of the design and fabrication of conductive polymer composite sensors for detecting and identifying organic vapors. A novel method was developed to optimize the selection of polymeric materials to be used within a chemiresistor array for anticipated samples without performing preliminary experiments. It is based on the theoretical predicted responses of chemiresistors and the criterion of minimizing the mean square error (MSE) of the chemiresistor array. After the number of chemiresistors to be used in an array and the anticipated sample chemistry are determined, the MSE values of all combinations of the candidate chemiresistors are calculated. The combination which has the minimum MSE value is the best choice. This can become computationally intensive for selection of polymers for large arrays from candidates in a large database. The number of combinations can be reduced by using the branch and bound method to save computation time. This method is suitable for samples at low concentrations where thermodynamic multi-component interactions are linear. To help users apply this polymer selection method for the sensors, a website including 10 solvents and 10 polymers was developed. Users can specify a target sample and obtain the best set of polymers for a sensor array to detect the sample. The activities of trichloroethylene and toluene in polyisobutylene were measured at very low concentrations. The activities for toluene are consistent with published values at higher concentrations. The values for trichloroethylene are a new contribution to the literature.

End-gated and centre gated mouldings have been assessed with varying thickness and sprue geometries for the centre gate. Alternative image analysis techniques are used to measure the orientation and length of injection moulded short and long fibres composite components. The fibre orientation distribution (FOD) measurements for both geometries have been taken along the flow path. In shear flow the FOD changes along the flow path, however the FOD remains relatively constant during expansion flow. The core width and FOD at the skin within a long glass fibre (LGF) specimen is different in comparison to a short glass fibre (SGF) specimen. Fibre length measurements have been taken from the extrudate, sprue and 2 positions within the centre gate cavity. The size of the sprue has little influence on fibre breakage if the moulding is more than 1 mm thick The SGF FOD prediction models within Autodesk Simulation Moldflow Insight 2014 (ASMI) have been validated against measured SGF data. At present, by default, the models over-predict the <cos2θ> for most geometries. When the coefficients are tailored for each model, drastic improvements are seen in the FOD prediction. The recently developed SGF RSC model accurately predicts the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts the FOD accurately in expansion flow. The measured LGF fibre length distribution (FLD) and FOD have been validated against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting <cos2θ>. The breakage prediction improves if measured FLD of the extrudate is input into the model. / Autodesk Ltd.

The main aim of this work id to provide integral methods to predict and characterize the properties of composite structures based on hybrid polymers and reinforcements, that could lead to useful results from an industrial point of view. This is addressed, if possible, by theoretical predictions of the effective properties by using the available experimental data. The first part is focused on the scientific achievements of the author that allowed a quantitative characterization of the main effective properties of several composite architectures from hybrid polymers and reinforcements, based on bio matrices, tailor-made matrices and different theoretical and simulation methods using computer software to allow good comparison. The second part defines the future research lines to continue this initial investigation. The main objectives are clearly defined to give the reader a sound background with the appropriate concepts that are specifically discussed in the following chapters. As a main objective, this research work makes a first attempt to provide a systematic analysis and prediction of composite hybrid structures. / El objetivo general del trabajo es proporcionar medios integrales para predecir y caracterizar las propiedades de las estructuras de compuestos basados en polímeros y refuerzos híbridos, principales que pueden producir resultados de utilidad práctica simultáneamente. Esto se logra comparando, siempre que sea posible, las predicciones teóricas de las propiedades efectivas con los datos experimentales disponibles. Una primera parte se ocupa de los logros científicos del autor que permitieron caracterizar cuantitativamente las principales propiedades efectivas de las arquitecturas de compuestos basados en polímeros y refuerzos híbridos, basados en matrices bio, auto-desarrollados y diferentes métodos teóricos y de simulación por ordenador utilizados para la comparación. La segunda parte identifica las orientaciones futuras para la evolución y desarrollo de la ciencia y la investigación. Los objetivos generales fueron subrayados y concisos para dar al lector una visión previa de los conceptos que serán discutidos específicamente en los siguientes capítulos. Indirectamente, apuntan hacia uno de los objetivos principales de este trabajo, a saber, proporcionar una dirección para el análisis sistemático de materiales compuestos a base de refuerzos híbridos. / L'objectiu general d'aquest treball es proporcionar els mitjos integrals per tal de predir i caracteritzar les propietats d'estructures de compòsits basats en polímers i reforçaments híbrids, que poden produir resultats amb utilitat pràctica simultàniament. Aquest objectiu s'aconsegueix comparant, sempre que és possible, les prediccions teòriques de les propietats efectives amb les dades experimentals disponibles. Una primera part es centra en els temes científics en què ha treballat l'autor que han permès caracteritzar quantitativament les principals propietats efectives de les arquitectures de compòsits basades en polímers i reforçaments híbrids, derivats de matrius bio, auto-desenvolupats i diferents mètodes teòrics i de simulació informàtica per a una correcta comparació. La segona part identifica les orientacions futures per tal d'establir l'evolució i desenvolupament de la ciència i investigació lligada a la temàtica de la tesi. Els objectius generals han sigut clarament definits per tal de donar-li al lector una visió prèvia i sòlida dels conceptes que es discuteixen en capítols venidors. Indirectament, apunten cap a un dels objectius principals d'aquest treball, a saber, proporcionar una direcció per a l'anàlisi sistemàtica de materials compòsits a base de polímers i reforçaments híbrids. / Motoc, D. (2017). Development of green composites based on epoxidized vegetable oils (EVOs) with hybrid reinforcements: natural and inorganic fibers [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90399

Polyelectrolyte multilayer capsules fabricated by layer-by-layer (LbL) self-assembly technique consistsing of core-shell structure have emerged as potential drug delivery systems along with their applications in micro-reactors, cosmetics, vaccines and antimicrobial coatings. Various ligands and stimuli responsive entities can be incorporated into the core and shell of the capsules for targeted delivery and/or controlled release applications. Though multilayer capsules have been studied extensively as delivery systems, their utility for encapsulation of hydrophobic drugs and multiple drugs have not been explored in detail so far. Application of traditional polyelectrolyte capsules has several limitations, which renders them inapplicable for encapsulation of multiple drugs, hydrophobic drugs and also for releasing drugs on demand without addition of the external photothermal agents such as metal nanoparticles into the shells of the capsules. Thus, in this thesis, an attempt has been made to develop novel multifunctional multilayered capsules to overcome the above mentioned limitations. We have formulated two novel methods to functionalize the core with cyclodextrin molecules and the shell of the capsules with two-dimensional material, graphene oxide (GO). The properties such as high surface area along with π bonds, broad NIR-absorption, superior photothermal conversion and antimicrobial activity of graphene oxide has been explored and it has been demonstrated that 2-D graphene oxide is unique compared to the regular polyelectrolytes. By functionalizing the shell of capsules with GO as one of the layer material, a simple and efficient way for encapsulating multiple drugs into core and shell of the capsules is achieved by utilizing the large surface area and amphiphilic nature of GO. Based on the unique optical absorption and photothermal conversion properties of GO, we have demonstrated a facile route for near-infrared (NIR)-laser triggered release with low laser power. In the second part, functionalization of the hollow core of the capsules has been functionalized using cylodextrin (CD)-incorporated CaCO3 porous sacrificial templates, where both CD-CaCO3 and CD-modified capsules are used as high efficient carriers for hydrophobic drugs. In the third part, synergistic antimicrobial therapy was achieved using composite graphene oxide/polymer LbL films by combining the intrinsic antimicrobial activity and photothermal conversion ability of graphene oxide and the results depicted superior antimicrobial activity towards E. coli. These composite films also can be used as efficient antimicrobial coatings on biomedical devices or implants. The thesis has been divided into five chapters based on the individual works. In Chapter 1, a brief review on the history of LbL self-assembly, mechanism of self-assembly along with factors affecting the process have been discussed. Followed by a brief discussion about the fabrication of multilayered hollow capsules (core-shell structure), their applications in drug delivery and fabrication of multifunctional multilayered capsules through core and shell have been discussed. Finally, recent developments in LbL self-assembly and multilayered hollow capsules using carbon based materials (fullerenes, carbon nanotubes and graphene oxide) and their biomedical applications have been presented. Chapter 2 deals with the study on fabricating multifunctional multilayered capsules for facile encapsulation of multiple drugs into the capsules, which is achieved by functionalizing the capsules with graphene oxide (GO) as one of the layer materials. The GO composite capsules exhibited unique permeability properties compared to traditional multilayered capsules made of two polyelectrolytes. Multiple drugs could be simultaneously encapsulated in the capsules in a simple and effective manner. These capsules were found to exhibit a “core-shell” loading property for encapsulation of dual drugs into the core and shell of the capsules respectively. In addition, the graphene oxide composite capsules showed excellent biocompatibility towards MCF-7 cells. This study is the first one that demonstrates the potential of hybrid polyelectrolyte capsules without the use of micelles or polymer-drug conjugates for multi-drug encapsulation. Chapter 3 deals with the development of a facile route for near-infrared (NIR)-light triggered release of encapsulated drugs from the multilayered capsules via incorporation of graphene oxide (GO) into layer-by-layer (LbL) assembled capsules without addition of any external additives such as metal nanoparticles (NPs) or carbon nanotubes (CNTs) into the shells of the capsules. Till now, there is no report on light-responsive drug delivery system by utilizing the NIR-optical absorption properties of GO. Here, graphene oxide (GO) plays a dual role, serving as a structural component of LbL capsules as well as strong NIR-light absorbing agent, which efficiently converts absorbed light into heat. Upon NIR-laser irradiation, the microcapsules were opened in “point-wise fashion” due to local heating caused by laser irradiation. The rupturing mechanism of the capsules has been clearly demonstrated using confocal fluorescence microscopy and high resolution transmission electron microscopy. The light-triggering ability of these capsules has been applied successfully to release the encapsulated anticancer drug, doxorubicin. Chapter 4 deals with simple and versatile simple routes for encapsulation of model hydrophobic drug. Encapsulation of hydrophobic drugs in pharmaceutical industries is always a big challenge due to limited number of available drug carrier systems and poor aqueous solubility of hydrophobic drugs. Here, by combining the special properties of cyclodextrins (CDs) with biodegradable inorganic calcium carbonate microparticles, the hybrid CD-CaCO3 mesoporous microparticles have been prepared for the first time. These CD-CaCO3 microparticles were utilized as sacrificial templates to prepare CDs-modified LbL capsules. We have demonstrated that both the hybrid CD-CaCO3 microparticles and CDs-modified capsules are potential carriers for encapsulation of model hydrophobic drugs (self-fluorescent coumarine and nile red dyes) with high loading efficiency using supramolecular host-guest interaction between entrapped CDs and hydrophobic dye molecules. Compared with other inorganic drug carrier systems (mesoporous silica), CaCO3 porous particles have better biocompatibility, biodegradability and cost-effective and without use of any organic solvents. Both these hybrid CD-CaCO3 microparticles and CDs-modified capsules can be good candidates for encapsulation of hydrophobic drugs without involving extreme chemical conditions for fabrication. Chapter 5 deals with development of facile synergistic method for killing pathogenic bacteria by combining the intrinsic antimicrobial activity of graphene oxide (GO) and unique photothermal conversion property of GO into a single material. We fabricated composite LbL films of graphene oxide (GO) and poly(allylamine hydrochloride) (PAH) films. Antimicrobial activity of these GO composite films has been studied using Escherichia coli (E. coli) cells by varying number of deposited layers on glass slides (20 to 80 layers) and results suggest that by increasing the number of deposited layers, antimicrobial activity is also increased gradually. Based on the unique optical properties of GO, photothermal therapy have been carried out for killing of E. coli using GO composite films by varying number of deposited layers (20 to 80 layers) by irradiation of NIR-pulse laser at 1064 nm wavelength (Nd:YAG, 10 ns pulse, 10 Hz). The photothermal results revealed the enhanced antimicrobial activity compared to GO composite films alone without NIR-laser irradiation. The synergistic photothermal killing ability along with intrinsic antimicrobial activity of GO films results in much faster killing compared to films alone.

Abstract Template assisted deposition was used to produce various nanomaterials including simple nanowires, nanorods, multi-segmented metal nanowires, core-shell nanowires, alloy and polymer wires and tubes. Anodized aluminum oxide (AAO) membranes were used as templates for the growth of the various structures using an electrochemical deposition method and also by wetting the porous templates. In the electrochemical deposition method, the pore size of the templates affects the rate of synthesis and the structures of the nanomaterials while in the wetting method, the viscosity and reaction time in the polymer solution influence the structures of the nanomaterials. A conventional two-step anodization procedure was used to synthesize thick AAO templates with porous hexagonal channels at a constant applied voltage and temperature. A maximum thickness of over 180 µm oxide layer could be fabricated using mild anodization at 60 V and 80 V. Compared to conventional mild anodization, these conditions facilitated faster growth of oxide layers with regular pore arrangement. Polyethylene glycol (PEG) containing ferromagnetic nanowires were synthesized using template assisted electrochemical deposition method. During the synthesis, simultaneous deposition of polymer and metal ions resulted nanowires coated with a uniform layer of PEG without interfering with the structure and magnetic properties of the nanowires. PEG-coated Ni nanowires were embedded in polyethylene diacrylate (PEGDA) matrix after the removal of the AAO templates. Comparison of results with and without a magnetic field during embedding showed that the presence of magnetic field supported embedding of nanowire arrays in polymer. Influence of using AAO templates with several pore diameters for the synthesis of bimetallic nanowires were studied by growing Ni-Fe and Ni-Co bi-metallic nanowires. At a constant applied current by using templates with a pore diameters of 60 nm alloy formed while with a pore diameter of 130 nm core-shell nanowires formed. Polyvinylidene fluoride (PVDF) films and nanotubes were synthesized using a solution recrystallization method that favored the formation of piezoelectric β phase thin films. Variation in the concentration of polymer in the mixture solution allowed synthesis of different types of structures such as PVDF composites, nanorods and nanocrystals with tunable morphologies. Keywords: One-dimensional structures, electrodeposition, porous alumina, ferromagnetic nanostructures, magnetic core-shell nanowires, alloys, polymer composite, stimuli-active, PEGDA, azobenzene, and PVDF.