Afin de protéger les denrées alimentaires, l’industrie d’emballage enduit sur un film une couche très fine de polymère pour augmenter ses propriétés barrière aux gaz. Le problème majeur de ces enduits, généralement faits de poly (chlorure de vinylidène), vient de leur production de gaz toxiques à l’incinération. Les restrictions environnementales mondiales évoluent rapidement et sont de plus en plus strictes. De ce fait, des bioplastiques sont envisagés comme alternative. Dans ce contexte, l’objectif de la présente thèse est d'étudier le revêtement de films poly(téréphtalate d’éthylène) avec un polysaccharide, le chitosane. Ce dernier possède de bonnes propriétés barrières au gaz à sec. Cependant, son application dans l’emballage est limitée à cause de son caractère hydrophile. Le but de notre étude est donc d'améliorer les propriétés barrières à sec du chitosane par l’ajout de nano-charges d’argile et sa résistance à l’humidité par greffage de l’acide palmitique à la chaine du chitosane. L'efficacité d'incorporation de la vermiculite a été confirmée par DLS, DVS et DRX. Un facteur d'amélioration de la barrière (BiF) d’environ 100 pour l'hélium et de plus de 10 pour le dioxygène avec l'addition de 50% de vermiculite a été obtenu à sec. Le greffage de l’acide palmitique a été confirmé par spectroscopie IR-TF, ATG, DSC et RMN. Les résultats de mesures de la perméabilité hélium montrent une amélioration de facteur de la barrière (BIF) de 2 d’une couche de chitosane-g-acide palmitique et vermiculite à 60% en poids par rapport au PET non revêtu à 98% HR. / In order to protect food, the packaging industry performs a film coating with a very thin polymer layer to increase its gas barrier properties. The major problem of these coatings is that they are generally made of poly(vinylidene chloride) which leads to a toxic gas production during incineration. In view of the rapid change of the global environmental restrictions that become quite stringent, bioplastics seem promising alternatives. In this context, this thesis deals with a fundamental study of poly(ethylene terephthalate) films coated with a polysaccharide: chitosan. Chitosan offers good barrier properties in dry conditions. However, its application in the packaging is limited because of its hydrophilic character. Therefore, the main goal of our work is on one hand to enhance the dry barrier properties of the material through adding nanoclays and on the other hand to improve its resistance to moisture by incorporating palmitic acid by grafting it to the chitosane backbone. The incorporation efficiency of vermiculite was confirmed by DLS, DVS and XRD. A barrier improvement factor (BiF) of about 100 for helium and more than 10 for dioxygen with the addition of 50% vermiculite was obtained under dry conditions. The grafting of palmitic acid has been confirmed by FTIR spectroscopy, ATG, DSC and RMN. The results of helium permeability measurements showed an improvement of the barrier factor (BIF) of 2 in the case of a chitosan-grafted-palmitic acid layer with 60 weight% of vermiculite compared to the uncoated PET at 98% RH.

In the last decades, intensive research has been carried out in order to replace oil-based polymers with bio-based polymers due to growing environmental concerns. So far, most of the barrier materials used in food packaging are petroleum-based materials. The purpose of the barrier is to protect the packaged food from oxygen, water vapour, water and fat. The mechanical and barrier properties of coatings based on starch-plasticizer and starch-poly(vinyl alcohol) (PVOH)-plasticizer blends have been studied in the work described in this thesis. The plasticizers used were glycerol, polyethylene glycol and citric acid. In a second step, polyethylene coatings were extruded onto paperboard pre-coated with a starch-PVOH-plasticizer blend. The addition of PVOH to the starch increased the flexibility of the film. Curing of the film led to a decrease in flexibility and an increase in tensile strength. The flexibility of the starch-PVOH films was increased more when glycerol or polyethylene glycol was added than citric acid. The storage modulus of the starch-PVOH films containing citric acid increased substantially at high temperature. It was seen that the addition of polyethylene glycol or citric acid to the starch-PVOH blend resulted in an enrichment of PVOH at the surface of the films. Tensile tests on the films indicated that citric acid acted as a compatibilizer and increased the compatibility of the starch and PVOH in the blend. The addition of citric acid to the coating recipe substantially decreased the water vapour transmission rate through the starch-PVOH coated paperboard, which indicated that citric acid acts as a cross-linker for starch and/or PVOH. The starch-PVOH coatings containing citric acid showed oxygen-barrier properties similar to those of pure PVOH or of a starch-PVOH blend without plasticizer when four coating layers were applied on a paperboard. The oxygen-barrier properties of coatings based on a starch-PVOH blend containing citric acid indicated a cross-linking and increase in compatibility of the starch-PVOH blends. Polyethylene extrusion coating on a pre-coated paperboard resulted in a clear reduction in the oxygen transmission rate for all the pre-coating formulations containing plasticizers. The addition of a plasticizer to the pre-coating reduced the adhesion of polyethylene to pre-coated board. Polyethylene extrusion coating gave a board with a lower oxygen transmission rate when the paperboard was pre-coated with a polyethylene-glycol-containing formulation than with a citric-acid-containing formulation. The addition of polyethylene glycol to pre-coatings indicated an increase in wetting of the pre-coated paperboard by the polyethylene melt, and this may have sealed the small defects in the pre-coating leading to low oxygen transmission rate. The increase in brittleness of starch-PVOH films containing citric acid at a high temperature seemed to have a dominating effect on the barrier properties developed by the extrusion coating process. / Over the last few decades, industry and academia have made joint efforts to generate knowledge about renewable barrier materials in order to replace the oil-based barrier materials currently used in food packaging. This work has focused on the possibility of producing a material with high oxygen barrier properties including polyethylene as a moisture protection. The flexibility of starch films was increased by adding poly(vinyl alcohol) (PVOH) to the starch and the addition of a plasticizer to the starch-PVOH blend films further increase the flexibility of the films. The plasticizers used were glycerol, polyethylene glycol and citric acid. Curing of the films reduce their flexibility. The addition of citric acid to a starch-PVOH blend increased the compatibility of the starch-PVOH blend and affected the barrier properties of the coating layers containing citric acid. When a sufficient number of coating layers was applied, the starch-PVOH-citric-acid coatings showed oxygen-transmission-rate-values similar to those of the pure PVOH and of the starch-PVOH blend without plasticizers. Polyethylene extrusion coating on pre-coated paperboard resulted in a clear reduction in the oxygen transmission rate of all the pre-coating recipes based on starch-PVOH blends. The polyethylene extrusion coating showed a higher oxygen transmission rate for a board pre-coated with citric-acid-containing recipes than for a board pre-coated with polyethylene-glycol-containing recipes.

No description available.

No description available.

Polymer Nanocomposites (PNC) are a new class of materials characterized by their large interfacial areas between the host polymer and nanofiller. This unique feature, due to the size of the nanofiller, is understood to be the cause of enhanced mechanical, electrical, optical, and barrier properties observed of PNCs, relative to the properties of the unfilled polymer. This interface can determine the miscibility of the nanofiller in the polymer, which, in turn, influences the PNC's properties. In addition, this interface alters the polymer's structure near the surface of the nanofiller resulting in heterogeneity of local properties that can be expressed at the macroscopic level. Considering the polymer-nanoparticle interface significantly influences PNC properties, it is apparent that some atomistic level of detail is required to accurately predict the behavior of PNCs. Though an all-atom simulation of a PNC would be able to accomplish the latter, it is an impractical approach to pursue even with the most advanced computational resources currently available. In this contribution, we develop (1) an equilibrium coarse-graining method to predict nanoparticle dispersion in a polymer melt, (2) a dynamic coarse-graining method to predict rheological properties of polymer-nanoparticle melt mixtures, and (3) a numerical approach that includes interfacial layer effects and polymer rigidity when predicting barrier properties of PNCs. In addition to the above, we study how particle and polymer characteristics affect the interfacial layer thickness as well as how the polymer-nanoparticle interface may influence the entanglement network in a polymer melt. More specifically, we use a mean-field theory approach to discern how the concentration of a semiflexible polymer, its rigidity and the particle's size determine the interfacial layer thickness, and the scaling laws to describe this dependency. We also utilize molecular dynamics and simulation techniques on a model PNC to determine if the polymer-nanoparticle interaction can influence the entanglement network of a polymer melt. / text

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No. of bitstreams: 1 DissLGPC.pdf: 2392298 bytes, checksum: a409c9e72a219a2757100cff85329f59 (MD5) Previous issue date: 2015-09-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Due to the high postharvest losses of fruit and vegetable, the development of new technologies, aiming to reduce losses and maintain quality has greatly increased. Improved packaging can bring great benefits to the whole production chain, including enhancing shelf life, ensuring quality, and increasing product sale potential. It is important to know each packaging material properties, such as the barrier properties. Moreover, recognizing and evaluating the potential use of new technologies, such as adding metallic nanoparticles to the materials used in packaging production, can improve their properties and contribute to reduce the high postharvest losses. This research aimed to develop a simple and effective method for evaluating permeability of plastic films containing silver nanoparticles used for food storage, as well as to evaluate their permeability in regular storage conditions. To determine the permeability of plastic films, permeation chambers were designed and constructed. Those chambers allow both the gas exchange through a plastic film and permeability measurements for each specific film. Low density polyethylene (LDPE) and polyvinyl chloride (PVC) films, with and without silver nanoparticle (NpAg) addition, were evaluated. The as-prepared permeation chambers were also used to evaluate the plastic film permeability during storage of strawberries. The results evidence that the permeation chambers as well as the developed method for measuring the permeability are efficient and convenient. Such chambers can also be used for many types of polymeric films. Likewise, the developed method for evaluating the permeability in storage conditions of fruits and vegetables is effective; thus, it can assist for planning modified atmosphere packaging applied to different produces. The difference found in permeability values of the tested films under storage conditions was up to 50% when compared to the values obtained under experimental conditions. However, there were no significant permeability differences in films with NpAg when compared to films without that additive. / Frente às elevadas perdas de frutas e hortaliças, o desenvolvimento de novas tecnologias, visando redução das perdas e manutenção da qualidade, tem demonstrando grande crescimento. Melhores condições de embalagem podem trazer grandes benefícios para toda a cadeia produtiva, aumentando a vida de prateleira, garantindo a qualidade e ampliando o potencial de comercialização destes produtos. Conhecer as propriedades de cada material de embalagem, como suas propriedades de barreira, é de grande importância. Além disto, conhecer e avaliar o potencial de utilização de novas tecnologias, como a adição de nanopartículas metálicas aos materiais usados na produção de embalagem, pode melhorar suas propriedades e contribuir para a redução das elevadas perdas pós- colheita atualmente observadas. Esta pesquisa teve como objetivo o desenvolvimento de um método simples e eficaz para avaliação da permeabilidade de filmes plásticos aditivados com nanopartículas de prata e utilizados na armazenagem de alimentos, bem como a avaliação de sua permeabilidade em condições práticas de armazenamento. Para a determinação da permeabilidade dos filmes plásticos, foram projetadas e construídas câmaras de permeação que permitem a troca gasosa através de um filme plástico e aferição da permeabilidade específica de cada filme. Foram avaliados filmes de polietileno de baixa densidade (PEBD) e de policloreto de vinila (PVC), com e sem adição de nanopartículas de prata (NpAg). As câmaras de permeação construídas foram também utilizadas para a avaliação da permeabilidade de filmes plásticos durante o armazenamento de morangos. Os resultados obtidos demonstram que as câmaras de permeação e o método desenvolvido para aferição da permeabilidade são eficientes e convenientes para avaliações de permeabilidade, podendo ser utilizado para diversos tipos de filmes poliméricos. Outrossim, o método desenvolvido para avaliação da permeabilidade de filmes em condições práticas de armazenamento de frutas e hortaliças é eficaz e, desta forma, pode auxiliar no planejamento de embalagens para atmosfera modificada de diversos produtos. Foram observadas diferenças de até 50% na permeabilidade dos filmes testados em condições de armazenamento, quando comparado aos valores obtidos em condições experimentais. Todavia, não foram observadas diferenças consideráveis de permeabilidade nos filmes aditivados com NpAg, quando comparados aos filmes sem este aditivo.

The barrier properties and long term strength retention of polymers are of significant importance in a number of applications. Enhanced lifetime food packaging, substrates for OLED based flexible displays and long duration scientific balloons are among them. Higher material requirements in these applications drive the need for an accurate measurement system. Therefore, a new system was engineered with enhanced sensitivity and accuracy. Permeability of polymers is affected by permeant solubility and diffusion. One effort to decrease diffusion rates is via increasing the transport path length. We explore this through dispersion of layered silicates into polymers. Layered silicates with effective aspect ratio of 1000:1 have shown promise in improving the barrier and mechanical properties of polymers. The surface of these inorganic silicates was modified with surfactants to improve the interaction with organic polymers. The micro and nanoscale dispersion of the layered silicates was probed using optical and transmission microscopy as well as x-ray diffraction. Thermal transitions were analyzed using differential scanning calorimetry. Mechanical and permeability measurements were correlated to the dispersion and increased density. The essential structure-property relationships were established by comparing semicrystalline and amorphous polymers. Semicrystalline polymers selected were nylon-6 and polyethylene terephthalate. The amorphous polymer was polyethylene terphthalate-glycol. Densification due to the layered silicate in both semicrystalline and amorphous polymers was associated with significant impact on barrier and long term creep behavior. The inferences were confirmed by investigating a semi-crystalline polymer - polyethylene - above and below the glass transition. The results show that the layered silicate influences the amorphous segments in polymers and barrier properties are affected by synergistic influences of densification and uniform dispersion of the layered silicates.

En la presente Tesis Doctoral se han usado diferentes estrategias para incorporar compuestos activos no volátiles y volátiles en películas biodegradables a base de almidón (S) procedente de diferentes fuentes, quitosano (CH) y mezclas CH:S. Se evaluaron las propiedades funcionales de las películas y las cinéticas de liberación del compuesto activo debido a la incorporación de los polifenoles del tomillo (TE) y del ácido tánico (TA). Además, las propiedades funcionales y cinéticas de liberación de películas de almidón obtenidos por casting o por termoconformado también fueron evaluados en función de la adición de eugenol (E) en forma libre o previamente encapsulado con diferentes materiales (proteína de suero de leche (WP) o lecitinas (LE) junto con maltodextrinas como agente coadyuvante). Los productos microencapsulados en polvo fueron obtenidos por atomización. El efecto de la incorporación de ácido oleico (OA) en los encapsulados, como soporte para el E, y CH, como estabilizador potencial de las capsulas también fue estudiado. Las diferentes formulaciones fueron caracterizadas antes y después del secado en términos de eficiencia de encapsulación (EE), estabilidad térmica, cinéticas de liberación y capacidad antioxidante y antimicrobiana. Los resultados mostraron que TE confirió a las películas de S y CH actividad antioxidante. Los polifenoles (TE y TA) interaccionaron con las cadenas de CH y actuaron como agentes de entrecruzamiento, mejorando el comportamiento mecánico de las películas y reduciendo la velocidad de liberación y la cantidad de polifenol liberado de las películas en agua y en disoluciones acuosas de etanol. El efecto opuesto fue observado cuando el TE fue incorporado en la matriz de S pura. Todas las películas con TE fueron más oscuras, más rojizas y menos transparentes, especialmente las matrices de S:TE, lo que sugiere que los compuestos de TE fueron escasamente encapsulados. Éstas películas mostraron la liberación más rápida y la mayor proporción de TE liberado. Se observó una buena EE en los polvos sin CH (87-98%). Sin embargo, el empleo de CH provocó una disminución de la EE en los polvos formulados con WP y con LE (22% y 46%, respectivamente). Las formulaciones mostraron un comportamiento similar en cuanto a la liberación de E en simulantes alimentarios de diferente polaridad, donde prácticamente el contenido de E fue liberado a una velocidad similar. El efecto antibacteriano de polvos sin CH contra E. coli fue coherente con su contenido de eugenol. Un efecto adicional positivo de OA se detectó en la actividad antilisteria de este polvo. El proceso de moldeo por termocompresión de las películas provocó importantes pérdidas de E (80-65%), minimizadas cuando se utilizó OA en las microcápsulas. En las películas con E no encapsulado, se promovió la retención de E debido a la formación de complejos S-E. La presencia de E microencapsulado aumentó las discontinuidades en la matriz polimérica, produciendo películas menos resistentes y elásticas. Las propiedades barrera se mejoraron al agregar microencapsulados a las películas, a excepción de las microcápsulas con OA. La liberación de E de las películas se vio afectada por la microcápsula, su composición y el simulante alimentario. En la película de S obtenida por casting, la adición de polvo E microencapsulado en las dispersiones formadoras de película modificó la microestructura de las películas, que fueron menos resistentes y menos elásticas con un contenido reducido de humedad, y una menor transparencia y permeabilidad al oxígeno en comparación con las películas formuladas con E no encapsulado. La adición de E microencapsulado con OA promovió la actividad antioxidante de las películas, especialmente en los simulantes alimenticios menos polares. Las películas S-EOA-LE fueron efectivas para prevenir la oxidación del aceite de girasol durante 53 días de almacenamiento a 30°C. / In the present Doctoral Thesis, different strategies have been used to incorporate non-volatile (polyphenols from thyme extract) and a volatile active compound (eugenol) into biodegradable films prepared with starch (S) of different sources or chitosan (CH) or with mixtures of CH:S. The functional properties and release kinetics of casted films prepared with pea starch or CH or CH:S blends were evaluated as affected by the incorporation of polyphenols from an aqueous thyme extract (TE) and tannic acid (TA), a polyphenol which was used as a cross-linking agent. Moreover, the functional properties and release kinetics of corn starch films, obtained by casting or by thermo-compression moulding, were evaluated as a function of the addition of eugenol (E) in free form or pre-encapsulated with different wall materials. In order to encapsulate E, whey protein isolate (WP) or soy lecithin (LE), as wall material, and maltodextrin (MD), as drying coadjuvant, were selected. Microencapsulate powders were obtained by spray-drying. The effect of the addition of oleic acid (OA), as eugenol carrier, and CH, as a potential capsule stabilizer, was also analysed. The different formulations were characterized before and after drying, in terms of encapsulation efficiency, thermal stability, release kinetics and antioxidant capacity and antimicrobial activity. Results showed that TE provided pea starch and chitosan films with antioxidant activity. Polyphenols (TE and TA) interacted with CH chains and acted as cross-linkers, thus improving the tensile behaviour of films and reducing the release rate and the amount of polyphenol released from the films in water and ethanol aqueous solutions. The opposite effect was observed when TE was incorporated into the pure S matrix. All the films became darker, more reddish and less transparent when TE was incorporated, and this effect was more marked in pure S matrices, which suggests that the TE compounds were poorly encapsulated. Thus, S:TE films showed the fastest delivery rate and the highest delivery ratio of TE. A good encapsulation efficiency (EE) of E was observed in the CH-free powders (87-98%). However, the use of CH provoked a marked EE decrease in both WP and LE powders (22% and 46%, respectively). The formulations exhibited similar E release behaviour in food simulants of different polarity, where practically the total E content was delivered at a similar rate. The antibacterial effect of CH-free powders against E. coli was also coherent with their eugenol content. An additional positive effect of OA was detected in terms of the antilisterial action of this powder. The process of thermo-compression moulding of the films led to important E losses (80-65%), which were minimised when using OA in the microcapsules (EOA-WP or EOA-LE). In the films containing non-encapsulated E, the retention of E was promoted due to the formation of E-starch complexes. The presence of microencapsulated eugenol increased the presence of discontinuities in the polymeric matrix, thus yielding films that were mechanically less resistant and stretchable, except for E-LE-S films, which became more resistant to break. The barrier properties were improved when adding microencapsulates to the films, except for OA-based microcapsules. Eugenol release from the films was affected by microcapsule, their composition and the food simulant. In starch film obtained by casting, the addition of microencapsulated eugenol powder in starch film-forming dispersions modified film microstructure, yielding less resistant and less elastic films with reduced moisture content, transparency and oxygen permeability as compared to casted films formulated with non-encapsulated eugenol. The addition of eugenol microencapsulated with OA promoted the preservation of the antioxidant activity of the films, especially in less polar food simulants. S-EOA-LE films were effective in preventing sunflower oil oxidation during 53 days of storage at 30¿C. / En la present Tesi Doctoral s'han usat diferents estratègies per a incorporar compostos actius no volàtils i volàtils en pel·lícules biodegradables a base de midó (S) procedent de diferents fonts, quitosano (CH) i mescles CH:S. Es van avaluar les propietats funcionals de les pel·lícules i les cinètiques d'alliberament del compost actiu a causa de la incorporació dels polifenoles del timó (TE) i de l'àcid tànnic (TA). A més, les propietats funcionals i cinètiques d'alliberament de pel·lícules de midó obtinguts per càsting o per termoconformat també van ser avaluats en funció de l'addició d'eugenol (E) en forma lliure o prèviament encapsulat amb diversos materials (proteïna de sèrum de llet (WP) o lecitines (LE) junt amb maltodextrines com a agent coadjuvant). Els productes microencapsulats en pols van ser obtinguts per atomització. L'efecte de la incorporació d'àcid oleic (OA) en els encapsulats, com a suport per al E, i CH, com estabilitzador potencial de les càpsules també va ser estudiat. Les diferents formulacions van ser caracteritzades abans i després de l'assecat en termes d'eficiència d'encapsulació (EE), estabilitat tèrmica, cinètiques d'alliberament i capacitat antioxidant i antimicrobiana. Els resultats van mostrar que es va conferir a les pel·lícules de S i CH activitat antioxidant. Els polifenols (TE i TA) van interaccionar amb les cadenes de CH i van actuar com a agents d'entrecreuament, millorant el comportament mecànic de les pel·lícules i reduint la velocitat d'alliberament i la quantitat de polifenol alliberat de les pel·lícules en aigua i en dissolucions aquoses d'etanol. L'efecte oposat va ser observat quan el TE va ser incorporat en la matriu de S pura. Totes les pel·lícules amb TE van ser més fosques, més rogenques i menys transparents, especialment les matrius de S:TE, la qual cosa suggerix que els compostos de TE van ser escassament encapsulats. Estes pel·lícules van mostrar l'alliberament més ràpid i la major proporció de TE alliberat. Es va observar una bona EE en les pols sense CH (87-98%). No obstant, la incorporació de CH va provocar una disminució de l'EE en les pols formulats amb WP i amb LE (22% i 46%, respectivament). Les formulacions van mostrar un comportament semblant quant a l'alliberament de E en simulants alimentaris de diferent polaritat, on pràcticament el contingut de E va ser alliberat a una velocitat semblant. L'efecte antibacterià de pols sense CH contra E. coli va ser coherent amb el seu contingut d'eugenol. Un efecte addicional positiu d'OA es va detectar en l'activitat antilisteria d'esta pols. El procés de modelat per termocompresió de les pel·lícules va provocar importants pèrdues de E (80-65%) , minimitzades quan es va utilitzar OA en les microcàpsules. En les pel·lícules amb E no encapsulat, es va promoure la retenció de E a causa de la formació de complexos S-E. La presència de E microencapsulat va augmentar les discontinuïtats en la matriu polimérica, produint pel·lícules menys resistents i elàstiques. Les propietats barrera es van millorar a l'agregar microencapsulats a les pel·lícules, a excepció de les microcàpsules amb OA. L'alliberament de E de les pel·lícules es va veure afectada per la microcàpsula, la seua composició i el simulant alimentari. En la pel·lícula de S obtinguda per càsting, l'addició de pols E microencapsulat en les dispersions formadores de pel·lícula va modificar la microestructura de les pel·lícules, que van ser menys resistents i menys elàstiques amb un contingut reduït d'humitat, i una menor transparència i permeabilitat a l'oxigen en comparació amb les pel·lícules formulades amb E no encapsulat. L'addició de E microencapsulat amb OA va promoure l'activitat antioxidant de les pel·lícules, especialment en els simulants alimentaris menys polars. Les pel·lícules S-EOA-LE van ser efectives per a previndre l'oxidació de l'oli de gira-sol durant 53 dies d'em / Talón Argente, E. (2018). INCORPORATION OF ACTIVE COMPONENTS IN BIOPOLYMER-BASED FILMS FOR FOOD USE [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/101283 / TESIS

The aim of this master thesis deals with the optimization of the preparation of thin hydrogel films based on polyvinyl alcohol (PVA) with the possibility of incorporating suitable additives (polyelectrolytes, plasticizers, etc.) into the structure of the prepared film to modify its properties. DEAE-Dextran hydrochloride and polyglutamic acid (PGA) were used as polyelectrolytes. The basic characterization of the properties was performed on modified films, which were compared with pure PVA films. The films were characterized by thickness, swelling ability, barrier properties, tensile properties, specific surface area, antimicrobial tests, and thermogravimetric analysis. The swelling ability of PVA/PGA films was very high, which may be a disadvantage for their use in the packaging industry. Swelling increases the amount of water in the matrix of the PVA film, what leads to a higher growth of microorganisms and to degradation of thin film. The water vapor transmission rate was greatly affected by the addition of a plasticizer. The small specific surface area of the films indicates a smooth surface that promotes good barrier properties. Films with the addition of a plasticizer showed relatively good mechanical properties. The values of tensile strength, elongation and elastic modulus were comparable to commercially available films such as polypropylene (PP) or polyethylene (PE). Based on all experiments, PVA, PVA/DEAEDextran films and their variants with the addition of glycerol as a plasticizer were evaluated as the best candidates for the use of these films as packaging materials. The follow-up work could be dealing with the optimization of PVA films for oxygen permeability. Furthermore, the possibilities of using these films in the packaging industry based on the relative humidity of the environment, could be defined as other interesting area of future research.

Thin films have been used to modify surface properties of various materials for many years. Plasma Enhanced Chemical Vapor Deposition (PECVD) is one of the possible methods for their preparation and this technique is applied in this work as well. An organosilicone – hexamethyldisiloxane – is used as precursor. Thin films are created on the surface of the substrate using mixture of precursor and oxygen in radiofrequently excited capacitively coupled plasma. The aim of the thesis is to find the optimal deposition conditions for production of transparent thin layers with good barrier capabilities, low oxygen transmission rate especially. Thin film depositions were realized for different compositions of the deposition mixture in continuous and pulsed mode of plasma with varying supplied power and duty cycle values. The deposition process itself was monitored in situ by optical emission spectroscopy. Thin film coatings were analyzed to determine their physical chemical properties (infrared spectroscopy, surface energy) and barrier properties. Using optical emission spectroscopy, important particles were identified in the deposition plasma. Vibrational, rotational and electron temperatures were determined from relative intensities of chosen fragments. Composition of thin films was studied by infrared spectroscopy. The best results of oxygen transmission rate were achieved with layers prepared from deposition mixture with high oxygen content. It was possible to improve barrier properties by performing deposition in pulsed plasma mode with 20–30% duty cycle. In this diploma thesis, optimal deposition conditions of thin films from hexamethyldisiloxane with low oxygen transmission rate were determined. It is possible to use these results in practical applications, such as corrosion inhibitors for archaeological objects. Optionally, they can be used in various industry branches where it is desirable and feasible to prevent oxygen access to the material by deposition of barrier coatings.