Made available in DSpace on 2017-07-21T20:42:46Z (GMT). No. of bitstreams: 1 Kairin Ribeiro.pdf: 6162677 bytes, checksum: 0f20c9db1f4680a94411d055fb3f2d62 (MD5) Previous issue date: 2014-08-15 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Researches based on the mixture of synthetic with natural polymers have intensified in recent times. The idea of using polysaccharides nano or micro level with polyolefins is the new of this work. Three compositions of polypropylene and commercial citrus pectin was prepared in proportions of 1, 3 and 5%. A coupling agent was used, the graphitized polypropylene with maleic anhydride to advance interaction between natural and synthetic particles. The obtaining of particles in nanometric scale pectin was made from colloid mill grinding. Some particles arrived near 100nm and majority the particles reached scales around 300nm. The structural analysis by X-ray diffraction and Fourier transform infrared spectroscopy demonstrated an interaction between maleic anhydride and pectin despite clusters of hydrophilic particles that were seen by scanning electron microscopy In the X-ray diffraction, the presence of crystals of sugars were detected. These crystals may have caramelized because processing temperatures are close to 200 C and were detected by colorimetry. Based on the mechanical data, it is possible realize that pectin had a plasticizing effect on the synthetic polymer, corroborating the rheological data and thermogravimetric tests, considering that the addition of higher amount of particles produces more thermal stability of the synthetic polymer. / Os estudos baseados na mistura de polímeros sintéticos com polímeros naturais têm se intensificado nos últimos tempos. A ideia de usar polissacarídeos em nano ou micro escala junto com poliolefinas é a novidade deste trabalho. Foram preparadas três composições de polipropileno e pectina cítrica comercial em proporções de 1, 3 e 5%. Foi utilizado um agente compatibilizante, o polipropileno grafitizado com anidrido maleico para favorecer a interação entre partículas naturais e as sintéticas. A obtenção de partículas em escala nanométricas de pectina foi feita partir de moagem em moinho coloidal e chegou próxima da faixa de 100nm, pois as partículas atingiram escalas em torno de 300nm. A análise estrutural feita por infravermelho e difração de raios-X demonstrou que houve interação entre o anidrido maleico e a pectina apesar dos aglomerados de partículas hidrofílicas que foram percebidos através da microscopia eletrônica de varredura. Também a partir dos dados de difração de raios-X, a presença de cristais de açúcares foram detectados, que por colorimetria podem ter se caralemizado devido temperaturas de processamento estarem próximas de 200ºC. A partir dos dados mecânicos, é possível perceber que a pectina teve um efeito plastificante no polímero sintético, corroborando com dados reológicos e com os testes termogravimétricos, considerando que quanto maior adição de partículas, maior a estabilidade térmica do polímero sintético.

L’objet de ce travail est la description de la dynamique de diffusion dans les polymères à l’approche de la transition vitreuse et notamment les processus de relaxation hors équilibre. Nous développons, pour les mélanges compressibles de polymères et polymère-solvant, un modèle thermodynamique qui permet de calculer les forces thermodynamiques dans des situations hors d’équilibre (formalisme général d’Onsager). La dynamique correspondante repose sur l’existence d’hétérogénéités dynamiques près de Tg dues aux fluctuations de concentration (modèle de Long et Lequeux). Nous avons développé deux méthodes. La première est basée sur une équation de Fokker-Planck décrivant, à l’échelle des hétérogénéités (quelques nm), la distribution des fluctuations de concentration de polymère et de solvant. Après l’étude des mécanismes de relaxation à cette échelle, nous étudions l’échelle macroscopique, pour rendre compte de la pénétration du solvant dans un matériau vitreux ou du séchage d’un mélange polymère-solvant près de Tg. La deuxième méthode consiste en la simulation de ces mécanismes de relaxation par une description spatiale. Celle-ci est basée sur une discrétisation de l’espace, chaque site pouvant échanger du solvant ou des monomères selon une dynamique décrite par des équations de Langevin non-linéaires couplées. Cette dernière méthode est plus générale mais plus coûteuse en temps de calculs. Nous montrons que les résultats obtenus des deux façons sont cohérents. Il s’agit de la première méthode permettant de décrire microscopiquement et quantitativement la diffusion de solvant près et en dessous de la transition vitreuse / The aim of this work is to describe the diffusion dynamics in polymers close to the glass transition (relaxation processes at non equilibrium states). A thermodynamic model for polymer-polymer and polymer-solvent blends is developed. It is able to compute the thermodynamic forces existing at non equilibrium for the mentioned blends (Onsagers formalism). The correspondent dynamic are based upon the existence of thermodynamic heterogeneities close to Tg due to concentration's fluctuations (Long-Lequeux model). Two methods were developed. The first is based on a Fokker-Planck equation which describes, at the heterogeneity scale (i.e. nanometric scale), the distribution of fluctuations of polymer and solvent. Following the study on the relaxation mechanism in the nanometric scale, a microscopic scale was then considered, in order to take in account either the solvent penetration within a glassy material or the drying of a polymer-solvent blend close to Tg. The second method consists in the simulation of the mentionned relaxation mechanisms using a spatial approach. This approach is based on a special discretization, each site being able to exchange solvent molecules or monomers according to the dynamics described by coupled non-linear Langevin equations. This second method is a more general approach. However the calculations related to it are more time-consuming. The results obtained by both methods are in good agreement. This is the very first method able to describe microscopically and quantitatively the solvents diffusion close to or below Tg

The impact strength of Nylon 6 was improved by adding Ethylene- n-Butyl acrylate- maleic anhydride (E-nBA-MAH) terpolymer with various concentrations from 0% (w/w) to 15% (w/w). The bare interaction energy between two polymers was investigated by using melting point depression approach utilizing both the Flory-Huggins (FH) theory and the Sanchez-Lacombe Equation of State (SL EOS). The solution of the mixture was electrospun, and the effects of process parameters on the expected radii of nanofibers were investigated. The effects of process parameters such as polymer concentration in solution, electrical field, diameter of syringe needle, feed rate, and collector geometry on nanofibers were studied. The statistical analysis to relate these parameters on the diameter of nanofibers was carried out by using Johnson SB distribution. The ratio of elastic modulus to viscosity coefficient of nanofibers was worked out by using AFM and combined viscoelastic models. The experiments were carried out on single fiber. The ratio came out to be a function of nanofiber diameter and terpolymer concentration. Isothermal crystallization kinetics and WAXS diffraction patterns of blends revealed and also SEM images supported that after 5% addition of elastomeric terpolymer, the interaction between the components of the blend gets weaker. The elastic modulus of the blend with 5% of terpoymer was greater than that of the neat Nylon 6, but the elastic modulus decreased for the blends containing more than 5% terpolymer.

The goal of the work is to study possibilities for the modification of interface in immiscible polymer blends, which determine to a large degree of the blend properties. For this purpose novel coupling agents (named SCA) containing 2-oxazoline, 2-oxazinone, and hydrosilane reactive sites have been prepared. In blends of amino- functional and carboxylic acid terminated polymers the oxazoline and oxazinone units of the SCA react selectively with one of the polymers and, therefore, the SCA should locate at the interface. The remaining hydrosilane sites can now be used for further modification, e.g. for crosslinking. In the thesis we discussed the effect of the SCA on the morphology and thermal and rheological properties of blends based on carboxylic acid terminated polystyrene (PS) and amino-terminated polyamide 12 (PA) or poly(methyl methacrylate) (PMMA). The morphology of the blends and the location of the SCA strongly depends on the processing conditions. The crosslinkability of the interface could be proven by changes in the solubility behavior of the blends.

The use of dense CO2 in polymer processing can provide a response to the need for more environmentally-friendly industrial processes. Products with high-purity, sterility, and porosity can be achieved using dense gas technology (DGT). Currently, DGT has been used in different aspects of polymer processing including polymerization, micronization, and impregnation. Due to its solubility in polymers, CO2 can penetrate and plasticize polymers, while impregnating them with low-molecular weight CO2 -soluble compounds. Biodegradable polymers and other medical-grade polymers have benefited from the application of DGT. Dense CO2 processing properties of inertness, non-toxicity, and affinity for various therapeutic compounds are specifically advantageous to the medical and biomedical industries. In this work, the different applications of DGT in polymer processing are revised, then implemented. The polymerization of polycarbonate (PC) and polycaprolactone (PCL) in dense CO2 are presented. The syntheses of both polymers were successful and were aided by the use of dense CO2 . A multi-stage approach using dense CO2 as a sweep fluid to extract the PC polymerization by-product phenol is reported. Polycaprolactone was synthesized with varying temperatures and dense CO pressures, then impregnated with a CO2 -soluble therapeutic agent. The impregnated PCL acted as a drug reservoir with a drug-loading of 27wt% and a sustained drug release profile was observed for all samples over several days. Polymer blends of PC/PCL have potential industrial and biomedical applications both in vivo and in vitro. The applicability of PCL can be extended by enhancing its mechanical properties by creating a bio-blend with a stronger polymer such as PC. In this work, PC/PCL nonporous and porous blends were produced. Three novel dense CO2 blending techniques were used. The macroporous PC/PCL blend was impregnated with a therapeutic agent using CO2 as the carrier. A drug loading of 20wt% was achieved and sustained drug release was observed over 3 days. The applicability of dense CO2 in polymer processing was further demonstrated by sterilizing macroporous PC/PCL blends and soft hydrogels with dense CO2 . The PC/PCL blends and hydrogels were inoculated with vegetative bacteria and bacterial endospores. Industrial standard sterilization levels were achieved.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17163号 / 工博第3653号 / 新制||工||1555(附属図書館) / 29902 / 京都大学大学院工学研究科化学工学専攻 / (主査）教授 大嶋 正裕, 教授 山本 量一, 教授 宮原 稔 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17229号 / 工博第3656号 / 新制||工||1556(附属図書館) / 29975 / 京都大学大学院工学研究科化学工学専攻 / (主査)教授 大嶋 正裕, 教授 瀧川 敏算, 教授 山本 量一 / 学位規則第4条第1項該当

This master’s thesis deals with plasticization of poly(3-hydroxybutyrate), polylactid acid and their blend. It explores effect of chemical structure of plasticizer on mechanical properties of this polymer blend and on its diffusion from the polymer blend. Syntheses of plasticizers based on oligomeric polyadipates, citrates, lactate and esters of 2 ethylhexanoic acid with poly(ethyleneglycol) were carried out. Molecular weight distribution of synthesized plasticizers was determined using gel permeation chromatography. Poly(3-hydroxybutyrate), polylactid acid and their blend were plasticized with synthesized and commercial plasticizers. From commercial, chosed plasticizers were based on citrates and ester of 2-ethylhexanoic acid with poly(ethyleneglycol). Thermal stability of selected commercial plasticizers in polylactid acid was studied using thermogravimetry. Diffusion of plasticizers from poly(3-hydroxybutyrate), polylactid acid and their blend during exposure to 110 °C was also investigated. Mechanical properties of prepared blends were tested by tensile test. Almost all used plasticizers showed positive softening effect in blend. The highest elongation at break was detected for the blend with commercial acetyltributylcitrate, where elongation at break reached 328 % relative to 21 % for neat non-plasticized blend.

No description available.

This research is focused on the investigation of phase morphology and blend stability within ionomeric perfluorocyclobutane (PFCB)/poly(vinylidene difluoride) (PVDF) copolymer blend membranes. The morphologies of these unique materials, designed as proton exchange membranes (PEMs) for proton exchange membrane fuel cells (PEMFCs), have been examined not only in the as-cast/as-received state, but also as a function of exposure to various ex-situ aging environments. The morphological investigations used to probe the response of these ionomer blends have been designed to mimic the environment within a PEMFC and will therefore enhance our understanding of the implications of morphological changes which may occur during fuel cell operation. Thermal annealing of the membranes has been conducted to determine the materials' morphological response to various temperatures in the absence of hydration. The results of these thermal annealing studies have facilitated the isolation of morphological contributions stemming from thermal exposure. Immersion of the blend membranes in liquid water has allowed for singular identification of the role of hydration in the blend membranes' morphological rearrangement and phase stability. However, as the typical fuel cell environment to which these membranes will be exposed is complicated by the presence of both temperature and humidity, our ex-situ investigations have also included the exposure of PFCB/PVDF copolymer blend membranes to simultaneous thermal annealing and hydration conditions – a treatment we refer to as "hygrothermal aging." This unique procedure serves as a simplified method whereby the complex fuel cell environment may be simulated, and the resultant morphological response researched. While the work presented herein has enhanced our understanding of the blend stability of the specific membranes investigated, we have also advanced the fundamental knowledge of the role of morphology with respect to the fuel cell performance of blend materials and the corresponding implications of morphological rearrangements. Such an understanding is essential in the development of morphology-property relationships and eventual optimization of membrane materials designed for use in fuel cells. / Ph. D.