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.

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For the aim of production of poly(ethylene terephthalate), PET based flame retardant composites / boron based flame retardant additives, 3.5 mole hydrated zinc borate and boron phosphate were synthesized. Zinc borate was synthesized with the reaction of boric acid and zinc oxide in both laboratory and pilot scale reactors. Effects of reaction parameters on kinetics of reaction and final product particle size were evaluated. Boron phosphate was synthesized via dry, wet and microwave methods. In addition to the synthesized flame retardant additives, several non-halogenated flame retardant additives, which were commercially available, were also used. Composites were prepared using twin screw extruder and molded by injection molding, followed by characterization in terms of flame retardancy behavior, mechanical and thermal properties, and morphologies. Based on the results of first stage experiments, aiming to determine effective additives, different amounts and combinations of triphenyl phosphate, triphenyl phosphine oxide, zinc borate and microwave produced boron phosphate were chosen and used in PET matrix. Flame retardancy of the composites were determined by conducting horizontal burning rate and limiting oxygen index (LOI) tests. Smoke emissions during fire were also measured. According to the LOI test results, LOI of neat PET was determined as 21%, and with the addition of 5% boron phosphate and 5% triphenyl phosphate together, LOI was increased up to 36%. The smoke density analysis results implied that, boron phosphate was a successful smoke suppressant for PET matrix. In addition to flammability properties, tensile and impact properties of the composites were also improved with flame retardant additives and expecially with the addition of triphenyl phosphate.

The present study was aimed at exploring the purification and modification of montmorillonite rich Turkish bentonites by organic salts and their subsequent effects on the morphology (X-diffractometry, transmission electron microscopy, scanning electron microscopy), melt flow index, mechanical (Tensile, Impact) and especially thermal stability (thermal gravimetric analysis, differential scanning calorimetry) properties of polymer/organoclay nanocomposites with and without an elastomeric compatibilizer. The bentonite clay mined from Resadiye (Tokat/Turkey) was purified by sedimentation, resulting in higher cation exchange capacity and thermal stability in comparison to unpurified clay, and then used in the synthesis of six thermally stable organoclays by replacing the interlayer inorganic sodium cations with two (alkyl, aryl) phosphonium and four di-(alkyl, aryl) imidazolium surfactant cations in an attempt to overcome the problem of early decomposition of alkyl ammonium organoclays usually used in polymer nanocomposites. An optimum amount of these organoclays (wt %2) was then used in the production of Polyamide 66 and Poly(ethylene terephthalate) based nanocomposites by melt blending with the help of an optimum amount of elastomeric compatibilizer (wt %5) which also acted as impact modifier. Phosphonium organoclays were used in the production of nanocomposites for both polymers, whereas imidazolium organoclays were used with PET only. The importance of clay purification was revealed in the removal of non-clay minerals available in the raw bentonite clay as confirmed by XRF and XRD, the significant increase in cation exchange capacity and the improved thermal stability of the purified clays as proven by TGA. The interlayer spacing of the phosphonium organoclays ranged from 1.78 to 2.52 nm indicating arrangement between pseudo-trilayers and paraffin-type chains, while the interlayer spacing of imidazolium organoclays ranged between 1.35 nm and 1.45 nm indicating a monolayer arrangement. The effects of chemical structure (chain type), counter ion and alkyl chain length on the thermal stability of the imidazolium salts were investigated. TGA analysis showed that the thermal stability of (alkyl, aryl) phosphonium and di-(alkyl, aryl) imidazolium organoclays proved to be superior to conventionally used quaternary alkyl ammonium organoclays. Not only the thermal stability of the organoclays prevented the nanocomposite from early decomposition, but these organoclays also improved the onset decomposition temperatures of PA66 and PET nanocomposites compared to the pure polymer owing to the dominant barrier effect of the silicate layers as a result of the formation of carbonaceous-silicate char. The reinforcement of PA66 with surface modified phosphonium organoclays and PET with surface modified phosphonium and imidazolium organoclays enhanced the mechanical and thermal properties of the binary and ternary nanocomposites. The mechanical properties were in good agreement with DSC analysis for all the PA66 and PET compositions. The presence of elastomer and organoclays promoted the nucleation process in PA66 blend, binary and ternary nanocomposites. However, the presence of elastomer and organoclay retarded the nucleation in most of the PET composites.

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Glass fiber reinforced poly(ethylene terephthalate), GF/PET has excellent potential for future structural applications of composite materials. PET as a semi-crystalline thermoplastic polyester has high wear resistance, low coefficient of friction, high flexural modulus and superior dimensional stability make it a versatile material for designing mechanical and electromechanical parts. Glass fibers are currently used as strength giving material in structural composites because of their high strength and high performance capabilities. In order to obtain high interfacial adhesion between glass fiber and polymer, glass fibers are treated with silane coupling agents. The objective of this study is to produce GF/PET composites with varying glass fiber concentration at constant process parameters in a twin screw extruder. Also, by keeping GF content constant, it is aimed to observe the effects of process parameters such as screw speed and feed rate on structural properties of the composites. Another objective of the study is to investigate the influence of different coupling agents on the morphological, thermal and mechanical properties and on fiber length distributions of the composites. Tensile strength and tensile moduli of the GF/PET composites increased with increasing GF loading. There was not a direct relation between strain at break values and GF content. The interfacial adhesion between glass fiber received from the manufacturer and PET was good as observed in the SEM photograps. Degree of crystallinity values increased with the addition of GF. Increasing the screw speed did not affect the tensile strength of the material significantly. While increasing the feed rate the tensile strength decreased. The coupling agent, 3-APME which has less effective functional groups than the others showed poor adhesion between glass fiber and PET. Therefore, lower tensile properties were obtained for the composite with 3-APME than those of other silane coupling agents treated composites. Number average fiber length values were reduced to approximately 300&amp / #61549 / m for almost all composites prepared in this study.

Philosophiae Doctor - PhD (Chemistry) / Rare earth elements (REEs) have widespread use and importance for industrial applications due to their metallurgical, optical and electronic properties. Several typical hydrometallurgical techniques such as adsorption, chemical precipitation, filtration, ion exchange and solvent extraction techniques have been used for separation and recovery of the rare earth metals from aqueous solutions. Adsorption was recognised as one of the most promising methods due to its simplicity, high efficiency and availability. Many adsorbents are being investigated but there are few adsorbents containing specific functional groups in practical use for REEs recovery. This aim of this study was to develop a nanofibre based adsorbent containing glycolic acid functional groups for the recovery of rare earth metals. Polystyrene (PS) and polyethylene terephthalate (PET) nanofibres were prepared by the electrospinning technique, glycolic acid functional groups were grafted onto the PS or PET nanofibres and the potential of the two modified nanofibre adsorbents for adsorption of Ce3+ or Nd3+ from aqueous solution were investigated and compared. The adsorption experiments were carried out to investigate the effect of different adsorption parameters such as pH, contact time and initial concentration in a batch system in order to achieve the objectives of this research.

Orientadores: Lucia Helena Innocentini Mei, Marcos Akira d'Avila / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-10T08:22:57Z (GMT). No. of bitstreams: 1 Bizarria_MariaTrindadeMarques_M.pdf: 2194752 bytes, checksum: 4e957a01de264fbcff7d460f5c539bac (MD5) Previous issue date: 2007 / Resumo: O estudo de nanocompósitos de poli(tereftalato de etileno) reciclado (PETr), principal objeto deste trabalho, foi dividido em duas partes. Preliminarmente, foram preparados nanocompósitos de PETr, com diversos teores (1, 3 e 5% em massa) de montmorilonita organicamente modificada (MMTm), pelo método de intercalação no estado fundido, em uma extrusora de dupla rosca corotacional à velocidade de 250 rpm. Buscando um melhor entendimento sobre as implicações que envolvem a preparação de nanocompósitos com respeito ao sistema PETr/MMTm disponível comercialmente, na segunda parte deste estudo, além de diferentes teores (neste caso 2,5 e 5,0%), distintas velocidades da rosca foram também utilizadas (250 e 150 rpm). Adicionalmente, para efeitos comparativos, foram ainda processados nanocompósitos com equivalentes formulações, porém com matriz de PET virgem. Como na primeira parte, a morfologia dos corpos de prova moldados por injeção foi avaliada por difração de raios-X (DRX) e microscopia eletrônica de transmissão (MET). As propriedades térmicas e mecânicas dos nanocompósitos obtidos foram então analisados por calorimetria diferencial exploratória (DSC) e testes de impacto e tração. As imagens de MET mostraram uma morfologia mista exibindo lamelas intercaladas e também algumas esfoliadas. Uma pequena quantidade de agregados pôde também ser observada. Teores mais elevados de MMTm conduziram a valores mais altos de cristalização desenvolvida dentro do molde de injeção, o que indica que a MMTm atuou como agente nucleante como ficou evidenciado pela diminuição e pelo aumento das temperaturas de cristalização, a frio e a partir do fundido, respectivamente, nos nanocompósitos resultantes. Os valores máximos para o módulo de Young foram observados nos nanocompósitos contendo 5% de MMTm processados a 150 rpm. A análise morfológica efetivamente revelou um maior grau de esfoliação para os nanocompósito baseados em matriz de PET virgem. Contudo a termo-estabilidade dos nanocompósitos de PETr, durante o processo de injeção, foi relativamente superior àquela mostrada pelos de PET virgem. A obtenção de nanocompósitos de PET reciclado (com vistas a futuras aplicações de engenharia) mostrou-se viável, mesmo quando comparada à de nanocompósitos com matriz do material virgem / Abstract: The study of the recycled poly(ethylene terephthalate) (rPET) nanocomposites, which was the main object of this work, has been divided into two parts. At first, nanocomposites of rPET with several amounts (1, 3 and 5wt.%) of an organic modified montmorillonite (mMMT) were prepared by direct melt intercalation process in a co-rotating twin-screw extruder at 250 rpm. In order to obtain a better understanding about the implications that involve the preparation of nanocomposites regarding the system rPET and a commercial mMMT, in the second part of this study, besides different amounts of mMMT (2.5 and 5.0% in this case), different screw rotation speed (250 and 150 rpm) were also used. In addition, as a reference, nanocomposites with the same formulations but with virgin PET matrix were also processed. As in the first part, the morphology of the injection-molded formulations was evaluated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal and mechanical properties of the resulting nanocomposites were then analyzed by differential scanning calorimetry (DSC), tensile and impact tests. The TEM images showed a mixed morphology with intercalated and some exfoliated platelets, a little amount of aggregated platelets could also be observed. Higher concentrations of mMMT led to higher values of crystallization into the mold. This indicates that mMMT actuated as nucleating agent, as evidenced by a decrease and an increase in both cold and melt crystallization temperatures in the obtained nanocomposites, respectively. Maximum enhancement in Young¿s modulus was observed in the nanocomposites containing 5 wt% of mMMT processed at 150 rpm. The morphological analysis has effectively revealed a better degree of exfoliation for the nanocomposites based in virgin PET matrix. However, the thermal stability of the rPET nanocomposites, during de injection-molding process, was relatively better than those of the virgin PET. The obtaining of rPET nanocomposites, having in mind future engineering applications showed availability even when compared with virgin material nanocomposites / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

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