Composites based on binary polymer blends of polystyrene (PS)/poly(ethylene-co-vinyl alcohol) (EVOH) (70/30 wt%) containing natural Montmorillonite, Na-MMTs (Nanomer PGW or Cloisite Na+) and organically modified Montmorillonite clays, OMMTs (Nanomer I.30T, Cloisite 30B or Cloisite 10A) were prepared via melt compounding. The interactions between the polymers and clays were studied using flow micro-calorimetry (FMC). Data obtained from FMC indicated that the probe molecule mimicking EVOH (butan-2-ol) interacted with the MMTs and OMMTs much more strongly than PS. Scanning electron microscopy (SEM) revealed that composites based on binary blends had dispersed/continuous morphologies, in which EVOH was dispersed in a PS matrix. The size of the EVOH droplets in the PS matrix increased with increasing clay loading. Transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD) were used to determine the extent of dispersion and location of clay in the PS/EVOH/clay composites. These techniques confirmed the formation of intercalated clay structures. As predicted by FMC, the clay platelets were selectively located in the EVOH phase, independent of the blending sequence and the type of organic modifier in the OMMT. Composites containing OMMTs showed better dispersion of platelets within the EVOH phase than those containing Na-MMTs. Differential scanning calorimetry (DSC); showed the crystallisation behaviour of EVOH to depend on the clay loading and the nature of the organic modifier in the OMMT. Nanomer PGW, Cloisite Na+ and Cloisite 30B acted as weak nucleating agents. In contrast, Nanomer I.30T and Cloisite 10A significantly hindered the crystallisation of EVOH in the blends due to the restriction of chain segment mobility. Dynamic mechanical thermal analysis (DMTA) confirmed that the presence of clay increases the storage modulus of the composites compared to an unfilled blend. In addition, the improvement in storage modulus reflected the dispersion state of the different clays and their interaction with the polymers of the blend. Ternary-blend based composites were formed by adding poly(styrene-co-acrylonitrile) (SAN) to the composites based on binary PS/EVOH blends. This resulted in a finer dispersion of the EVOH phase and the development of a core-shell morphology, in which SAN encapsulated and formed shells around EVOH droplets. In contrast to binary blend composites, the clay platelets were found at the interface between SAN and EVOH in the ternary blends.

Cette thèse présente l’élaboration de thermodurcissables et de composites biosourcés synthétisés à partir d’huiles végétales époxydées (lin et soja) et d’alcool furfurylique (FA). La première partie de ce travail concerne l’étude de la polymérisation du FA en polyalcool furfurylique (PFA) (i) en solvants protiques polaires, (ii) en combinaison avec le bois et (iii) suivant l’ajout de nouveaux amorceurs. En solvant, les changements de structures observés ont été reliés aux propriétés thermomécaniques. Une autre modification de structure du PFA a été obtenue grâce au 2,5 diméthylfurane. Ce travail a permis d’obtenir une meilleure compréhension de la réactivité du FA au sein du bois et montre que les composites bois/PFA ont une densité et une résistance plus élevées que leurs homologues non modifiés. Enfin, l’amorçage des réactions du FA par l’acide lévulinique ou par le p-toluène sulfonylhydrazine permet de proposer deux nouveaux amorceurs, respectivement biosourcé et « latent ». La seconde partie de ce travail concerne l’élaboration d’une résine époxyde totalement biosourcée et synthétisée à partir d’huiles végétales époxydées. L’huile de lin et de soja ont été chacune copolymérisées avec un acide dicarboxylique. Un premier travail fondamental a consisté à corréler la réactivité de copolymérisation avec les structures des polymères obtenus puis à établir le lien avec les propriétés thermomécaniques. Ensuite, des nanocomposites ont été synthétisés à partir de ces résines époxydes et de sépiolite. Les différentes voies de dispersion et de modification de la sépiolite mises en œuvre conduisent à des niveaux de dispersion différents de la nanocharge au sein de la matrice. / The work presents the elaboration of biobased thermosets and composites synthesized from epoxidized vegetable oils (linseed and soybean) and furfuryl alcohol (FA). A first area of research focused on the study of the polymerisation of FA into polyfurfuryl alcohol (PFA) (i) in protic polar solvents, (ii) in combination with wood and (iii) in the presence of new reaction initiators. In presence of solvents, the observed structural changes have been linked to the thermomechanical properties. Another PFA structure modification was obtained with 2,5 dimethylfuran. This work allowed a better understanding of the reactivity of FA within the wood and shows that the obtained wood/PFA composites have higher density and resistance than their non-modified equivalents. Finally, the initiation of FA polymerization by levulinic acid and p-toluene sulfonylhydrazine, respectively biobased and « latent » initiators has been studied. The second topic of thesis concerns a new type of fully bio-based epoxy resin synthesized from epoxidized vegetable oils. Linseed and soybean oils have both been copolymerized with a dicarboxylic acid as curing agent. A first fundamental work was to correlate the reactivity of copolymerization with the polymer structure and to link them with thermomechanical properties. The obtained thermosets have been used to prepare nanocomposites with sepiolite. Different methods of dispersion and/or modification of sepiolite conduct to diverse morphologies of nanofiller dispersions into the matrix.

Made available in DSpace on 2014-12-17T14:07:16Z (GMT). No. of bitstreams: 1 EdnaMSC_DISSERT.pdf: 4754889 bytes, checksum: 7ba8ec4a5f3d11921ca74b85b2fe0b3b (MD5) Previous issue date: 2013-07-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This employment has the function the utilization of mango seeds Tommy Atkins, like starch source to obtain biopolymers and fibers source and nanowhiskers cellulose also, that will be use like reinforcing fillers in micro and nanobiocomposites polymeric. The fibers in natura removed from tegument mango seed were characterized, as weel as the treated fibers and nanowhiskers of cellulose extracted from them. The starch extracted from seed s almond showed a good performance (32%) and a high purity. The chemicals analyzes, of crystallinity and morphological of the fibers in natura, treated fibers and nanowhiskers of cellulose confirmed the efficacy of the chemical treatement performed to remove amorphous constituents (hemicellulose and lignina). The thermoplastic starch (TPS) obtained from two sources, corn starch and starchy material mango, was produced in a twin screw extruder with compositon mass of 62,5% of starch, 9,4% of water and 28,1% of glycerol. The starch material mango was the main objective of this work for the production of biodegradable materials, and the starch corn was utilized during the production stage to evaluate the processability of the starch and use as parameter for comparison, according of being a conventional source for obtaining conventional comercial starch. The incorporation of fibers (6% in mass) and nanowhiskers cellulose (1% in mass) in matrix of TPS to obtain composite and nanocomposite, respectively, it was performed in single screw extruder. The biocomposites and bionanocomposites polymeric were obtained and the TPS from starchy material mango presented better results of thermal and mechanicals properties when compared to TPS corn starch. Concludes that the sediment generated of the agroindustrial processing mango used presents potencial to producing of biodegradables materials / Este trabalho apresenta como objetivo a utiliza??o de caro?os da manga Tommy Atkins, como fonte de amido para obten??o de biopol?meros e, tamb?m, como fonte de fibras e nanowhiskers de celulose, que foram utilizadas como cargas refor?antes em micro e nanobiocomp?sitos polim?ricos. As fibras in natura removidas do tegumento do caro?o de manga foram caracterizadas, bem como as fibras tratadas e nanowhiskers de celulose extra?dos a partir delas. O amido extra?do das am?ndoas do caro?o apresentou um bom rendimento (32%) e elevado grau de pureza. As an?lises qu?micas, de cristalinidade e morfol?gicas das fibras in natura, fibras tratadas e nanowhiskers de celulose confirmaram a efic?cia do tratamento qu?mico realizado em remover os constituintes amorfos (hemicelulose e lignina). O amido termopl?stico (TPS) obtido de duas fontes, amido de milho e material amil?ceo de manga, foi produzido em extrusora rosca dupla com a composi??o em massa de 62,5% de amido, 9,4% de ?gua e 28,1% de glicerol. O material amil?ceo de manga foi o objetivo principal deste trabalho para produ??o de materiais biodegrad?veis, e o amido de milho foi utilizado durante a etapa de produ??o para avaliar a processabilidade do amido e utilizar como par?metro de compara??o, em fun??o de ser uma fonte convencional de obten??o de amido comercial. A incorpora??o das fibras (6% em massa) e nanowhiskers de celulose (1% em massa) em matriz de TPS para obter comp?sitos e nanocomp?sitos, respectivamente, foi realizada em extrusora monorosca. Os biocomp?sitos e bionanocomp?sitos polim?ricos foram obtidos e os TPS do material amil?ceo de manga apresentaram melhores resultados de propriedades t?rmicas e mec?nicas quando comparados aos TPS de amido de milho. Concluiu-se que os res?duos gerados do processamento agroindustrial da manga utilizados apresentaram potencial para a produ??o de materiais biodegrad?veis

Tato dizertační práce se zabývá přípravou a charakterizací nanokompozitních polymerních pěn se zaměřením na strukturu materiálu a aplikaci v 3D tisku. Cílem práce je studium materiálu s vysoce organizovanou hierarchickou strukturou – od nanoměřítka, přes mikroskopickou strukturu po makroskopická tělesa. V první části práce byly řešeny strukturní vlastnosti nanokompozitů připravených z polymerních skel roztokovou metodou. Byl hledán obecně platný trend, pomocí kterého by bylo možné předpovídat disperzi nanočástic v kompozitu. Ukázalo se, že řídícím faktorem může být závislost na rozdílu parametrů rozpustnosti polymeru a rozpouštědla. Tento poznatek byl ověřen na systémech obsahujících různé nanočástice, polymery a rozpouštědla. Se znalostí principů pro řízení struktury nanokompozitů byly připraveny nanokompozity impaktního polystyrenu plněného nanosilikou. Tyto nanokompozity posloužily jako základ pro přípravu polymerních nakompozitních pěn. Porézní struktury bylo dosaženo pomocí termálního chemického nadouvadla azodikarbonamidu. Z těchto materiálů byly extrudovány filamenty, které byly následně zpracovány pomocí 3D tisku do požadovaných tvarů a vypěněny. Výsledkem byla hierarchická struktura s organizací struktury od nano (organizace nanočástic), přes mikro (struktura dvoukomponentní polymerní směsi a struktura pěny) po makroměřítko (struktura pěny a design 3D tisku). Byl pozorován vliv nanočástic na strukturu a termální a mechanické vlastnosti polymerních pěn. Nanočástice fungují při tvorbě pěny jako nukleační činidlo, na jejich povrchu snadno dochází k tvorbě pórů, takže s obsahem nanočástic v materiálu bylo vytvořeno více menších pórů, což napomohlo k homogenitě pěnové struktury. Přítomnost nanočástic změnila povrchovou energii zrn nadouvadla, díky čemuž docházelo k jeho rozkladu za nižích teplot a pěnění bylo i rychlejší. Nanočástice mají zároveň potenciál vyztužit stěny pěny a zlepšit tak mechanické vlastnosti. 3D tisk je oblíbená a hojně rozšířená technika, díky své jednoduchosti je v mnoha laboratořích a zkušebnách, proto roste poptávka po filamentech se speciálními vlastnostmi. Materiál vyvinutý v této dizertační práci je v podstatě hotovým a charakterizovaným produktem, který by mohl přispět k uspokojení této pohledávky.

For the commercial success of polymer - multiwalled carbon nanotube (MWNT) composites the production of these materials on industrial scale by melt processing is of significant importance. The complete dispersion of primary MWNT agglomerates in a polymer melt is difficult to achieve, making it an important and challenging technological problem. Hence, it is necessary to understand the process of MWNT agglomerate dispersion in a polymer melt. Based on an intensive literature research on mechanisms and influencing factors on dispersion of other agglomerated nanostructured fillers (e.g. carbon black), the main dispersion steps were evaluated and investigated concerning the agglomerated MWNT.Consequently, systematic investigations were performed to study the effect of the melt infiltration on MWNT agglomerate dispersion and to analyse the corresponding main dispersion mechanisms, namely rupture and erosion. The states of MWNT agglomerate dispersion were assessed by quantifying the agglomerate area ratio and particle size distribution using image analysis of optical transmission micrographs. Additionally, the composite’s electrical resistivity was determined. In the prevailing study, polycarbonates (PC) varying in molecular weight were used to produce composites containing 1 wt% MWNT (Baytubes C150HP) as model systems and a discontinuous microcompounder was applied as melt mixing device. The agglomerate structure of the used MWNT material made them especially suitable for the reported investigations. The step of melt infiltration into the primary nanotube agglomerates plays a crucial role for their dispersion in the PC melt. During melt mixing when low shear rates were applied, better state of MWNT dispersion was obtained in high viscosity matrices because applied shear stresses were high. On the contrary, if high shear rates were applied, similar states of MWNT dispersion were obtained in low and high viscosity matrices although significantly lower shear stresses were applied in the low viscosity matrix as compared to the high viscosity matrix. The results indicate that if the applied shear stress values are compared, with increasing matrix viscosity the agglomerate dispersion gets worsen. This is attributed to the fact that low viscosity matrices can infiltrate relatively faster than high viscosity matrices into the agglomerate making them weaker and reducing the agglomerate strength. Thus, at sufficient shear rates MWNT agglomerates disperse relatively faster in low viscosity matrix. This illustrates a balance between the counteracting effects of viscosity on agglomerate infiltration and agglomerate dispersion. Additionally, the effect of matrix molecular weight on the size of un-dispersed MWNT agglomerates was investigated. Under similar conditions of applied shear stress, the composites based on low molecular weight matrix showed smaller sized un-dispersed primary agglomerates as compared to composites with higher molecular weight matrices. This again highlights the role of matrix infiltration as the first step of dispersion. Following the step of melt infiltration, agglomerate size gets reduced due to the dispersion mechanisms. To analyse the corresponding contributions of different dispersion mechanisms (rupture and erosion), the kinetics of MWNT agglomerate dispersion was investigated. If high mixing speeds are employed dispersion is quite fast and needs less time as compared to low mixing speed. A model is proposed to estimate the fractions of rupture and erosion mechanisms during agglomerate dispersion based on the kinetic study in the discontinuous mixer. Under the employed experimental conditions, at high mixing speeds, the dispersion was found to be governed by rupture dominant mechanism, whereas at low mixing speeds the dispersion was controlled by both mechanisms. As far as electrical resistivity is concerned, for a given content of MWNT as the state of dispersion improves, the resistivity values decrease significantly but only up to a plateau value. The composites produced using low viscosity matrices have lower resistivity values as compared to high viscosity matrices. Additionally, composites were prepared using additives, whereas the additives were found to be useful for improving filler dispersion and electrical conductivity.