Bioplastics are emerging as most promising materials to replace oil based thermoplastics particularly in packaging. Bioplastics can mitigate and address concerns about the negative role of plastics in the environment creating pollution and depleting resources hence bioplastics can enable an innovative approach toward addressing these issues. However, manufacturing of bioplastic is still costly and their mechanical and thermal properties require extensive development. Therefore there has been substantial interest to improve processing and properties of bioplastics to diminish the environmental impacts caused by continuous use of synthetic polymers of petroleum origin. In this research, Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV and Polybutylene succinate (PBS) composites and blends were developed to improve the properties of PHBV as the matrix polymer and hence produce a novel formulation for product development. Three approaches were studied in this work:  The effect of talcum powder as a nucleating agent and reinforcing filler.  The effect of oligomer chain extenders on miscibility, crystallinity, thermal and thermomechanical, mechanical and morphological properties of PHBV/PBS blends.  The effect of acrylic core-shell impact modifier on crystallinity, thermal and thermomechanical, mechanical and morphological properties of PHBV were also evaluated. All the above scientific approaches have been studied. It was noticed that talc can change the sluggish crystallinity of PHBV. Talc enhances nucleation of PHBV in the composites which leads to a faster crystallization rate. The heat distortion temperature, crystallinity and the modulus of PHBV/talc composite were also increased. In the presence of the chain extender (CE) the miscibility conditions of PHBV/PBS blends were changed. The results were supported by calculation of the activation energies. The elongation at break and tensile strength of PHBV/PBS/Chain extender blends increased indicating miscibility change. The possible reaction mechanism between PHBV, PBS and CE are proposed and the results supported by using FTIR. Immiscibility results of the PHBV/PBS blends are supported by SEM images. Addition of the impact modifier to PHBV reduced the crystallization rate and prolonged crystallization time. It has been found that the shell of impact modifier (PMMA) is partially miscible with PHBV. The absorbed impact energy is improved by the impact modifier but the improvement was not as satisfactory as results noted for PLA. The SEM images showed the average fine dispersion of different sized particles inside the matrix.

Thesis (PhD)--University of South Australia, 1996

Cette étude s’inscrit dans le projet ANR Blanc COPIN qui a pour but de développer et de comprendre les nanocomposites à partir de nanoparticules inorganiques mélangées à un polymère semi-cristallin. L’innovation du partenaire du projet, Imerys, a été de synthétiser des particules de talcs à l’échelle nanométrique. Le talc étant connu pour ces effets nucléants, l’objectif est d’utiliser ces nanoparticules pour voir leur influence sur un matériau semi-cristallin et plus spécifiquement sur la cristallisation de ce dernier lorsqu’elles sont orientées. Différents talcs synthétiques ont été étudiés changeant au niveau de leur durée de synthèse ou encore de leur modification de surface. Pour cela, la première partie de cette étude a été de disperser le talc en utilisant ou non des modifications chimiques de surface ainsi que des compatibilisants afin d’obtenir le meilleur état de dispersion et de distribution des particules. Ces continuums d’interactions ainsi créés montrent une nette amélioration de l’état de dispersion mais aussi l’amélioration des propriétés telles que la tenue en température. Les parties suivantes ont concernées plus spécifiquement la cristallisation en convoitant d’expliquer comment les nanoparticules peuvent s’orienter lors de l’écoulement tel que le cisaillement, comment elles génèrent une orientation cristalline spécifique du à leur effet nucléant, quel est le mécanisme prépondérant de la cristallisation entre la nucléation par l’orientation de macromolécules ou la nucléation provenant des nanoparticules. Il a aussi été question de déterminer les morphologies cristallines des nanocomposites lors du cisaillement / This study is part of the ANR Blanc COPIN which aim is to develop and understand the nanocomposites from inorganic nanoparticles mixed with a semi-crystalline polymer. The innovation of the project partner, Imerys, was to synthesized talc particles at the nanoscale. Talc is known for his nucleating effects and the goal is to use these nanoparticles to see their influence on a semi-crystalline material. Several synthetic talcs were employed differing from the synthesis time and chemical surface modifications. For this, the first part of this study was to disperse the talc using or not chemical modifications of surfaces as well as compatibilizers to obtained the best dispersion state and particles distribution. These continuums interaction created show a real improvement in the dispersion but also of properties such as heat resistance. The following parties concerned more specifically the crystallization trying to explain how nanoparticles can be oriented during shear flow, what is the leverage of these talcs on the crystallization when it was oriented, how they generate a specific crystal orientation coming from their nucleating effect, which is the predominant mechanism of crystallization nucleation between the macromolecules orientations or the nucleation of nanoparticles. It was also a question of determining the resulting crystal morphologies

Endometrial cancer is the most common female reproductive cancer in the United States. Most known risk factors for endometrial cancer are either genetic or related to exposure to estrogens; less is known about risk due to environmental exposures. While several studies have examined the relationship between perineal powder use and ovarian cancer risk, only one study has addressed the relationship with endometrial cancer risk. The Women's Health Initiative Observational Study, a prospective cohort study of 93,676 United States postmenopausal women from 1993-2005, measured perineal powder use at baseline via self-report. Cases of endometrial cancer were self-reported and confirmed by both local and central physician adjudicators. Cox proportional hazards regression was used to examine the association between perineal powder use and endometrial cancer, adjusting for known risk factors. Of the 48,912 women in our analysis, 25,181 (52%) reported ever use of perineal powders. There were 452 incident cases of endometrial cancer diagnosed during 366,872 person-years of follow-up. Ever use of perineal powder was not significantly associated with increased risk of endometrial cancer (hazard ratio 1.05, 95% confidence interval 0.87-1.27). However, use of any perineal powder for 20 or more years was associated with a 30% increase in risk (hazard ratio 1.30, 95% CI 1.01-1.67) compared to never users. Use of powder on both a diaphragm and the perineal area was associated with a 39% increase in risk (hazard ratio 1.39, 95% CI 1.00-1.93). Cessation of perineal powder use, particularly on a diaphragm, may help reduce risk of endometrial cancer.

No / The aims of the present work were to pelletize talc by extrusion-spheronization technique using microcrystalline cellulose (MCC) as a pelletization aid and to study its performance as a neutral substrate for coating. A 32 factorial design was used to study the effect of independent variables (X1, amount of talc, and X2, MCC) on pellet properties.

Les matériaux et minéraux argileux, abondent au Gabon. Les travaux pionniers révèlent la présence d’argiles rouges dans la série barrémienne de l’Agoula et d’argiles rouges à violettes dans la série néocomienne de Ndombo. Les argiles constituent une ressource précieuse et abondante qui a été largement valorisée tant en constructions traditionnelles de terre crue qu'en terre cuite en divers endroits du pays. Les présentes recherches sont initiées pour inventorier les ressources en différentes argiles facilement accessibles au Gabon, et dédiées à sélectionner des gisements à potentiel applicatif, selon la nature des argiles. Ce travail a été réalisé dans les régions de Libreville et de Tchibanga. Les échantillons prélevés font l’objet d’analyses macroscopique, microscopique, chimique, structurale et superficielle. Des essais de formulation font l’objet d’applications dans les domaines des briques, tuiles et celui des réfractaires. La croissance démographique de la République Gabonaise engendre une demande importante en divers matériaux locaux qui satisfassent les besoins de la vie courante. L’accent est mis sur les applications relatives aux terres cuites : briques, tuiles et carreaux. Des zones d'intérêt à potentiel économique sont identifiées. Les argiles de la région de Libreville, riches en kaolinites et illite sont intéressantes pour des applications en terre cuite. La caractérisation des propriétés minéralogiques des roches argileuses, est réalisée dans le but d'identifier les usages industriels les plus intéressants. Les caractérisations et les tests d’applications, identifient des matières premières pour la construction, la céramique, mais aussi dans bien d'autres domaines comme la pharmacologie (galénique), la papeterie, la cosmétique, l’agro-alimentaire, le caoutchouc, la peinture, le génie civil, le génie de l’environnement. Comme dans tous les pays d’Afrique Centrale, le développement durable passe inéluctablement par une maîtrise des ressources locales. La caractérisation fine des argiles du crétacé de Libreville est réalisée par : diffraction des rayons X, spectrométrie infrarouge à transformée de Fourier, microscopie électronique à balayage, détermination de la capacité d’échange cationique, granulométrie, analyses chimiques, indice de plasticité, test de céramique. Selon la diffraction des rayons X, ces argiles sont à kaolinite, et/ou illite et montmorillonite, quartz, ± muscovite, ± microcline, ± hématite, ± rutile, ± anatase. L’observation en Microscopie Electronique à Balayage et le traitement à l’Ethylène Glycol ou chauffé à 550°C analysé en DRX confirme la présence prépondérante de ces minéraux / Materials and clayey minerals abound in the Gabon. The pioneers works reveal the presence of red clays in the barrémian series of Agoula and red clays with violets in the neocomian series of Ndombo. Clays constitute a precious and plentiful resource which was widely beneficiated as well in traditional constructions of green clays as in terra-cotta in diverse places of the country. The present researches aim at inventorying the resources in various clays easily accessible in Gabon, and in the study of selection of deposits with application potential, according to the nature of clays. This work is carried on in the regions of Libreville and Tchibanga. The collected samples are the object of macroscopic, microscopic (tiny), chemical, structural and superficial analyses. Trials of formulation are the object of applications in the domains of bricks, tiles and refractories. The population growth of the Gabonese Republic generates a demand in diverse local materials satisfying the needs for the current life. The emphasis is put on the applications concerning terra-cottas: bricks, roof tiles and floor tiles. Zones of interest with economic potential are identified. Clays of the region of Libreville, rich in kaolinites and illite are interesting for applications in terra-cotta. The characterization of the mineralogical properties of the clayey rocks is realized with the aim of identifying the most interesting industrial uses. Characterizations and tests of applications, identify raw materials for the construction, the ceramic, but also in many other domains as pharmacology (galenic), paper industry, cosmetics, food-processing industry, rubber, paint, civil engineering and environment engineering. As in all the countries of Central Africa, the sustainable development passes inevitably by a control of the local resources. The fine characterization of clays of the Cretaceous of Libreville is realized by: X-ray Diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, determination of the cation exchange capacity, particle size analysis, chemical analyses, plasticity index, ceramic tests. According to the X-ray diffraction, these clays are mixtures of kaolinite, and/or illite and montmorillonite, quartz, ± muscovite, ± microcline, ± hematite, ± rutile ± anatase. The observation in Scanning Electron Microscopy and the treatment with Ethylène Glycol or heating at 550°C in XRD confirms the dominating presence of these minerals

L’incorporation de nanoplaquettes d’argile dans une matrice ou un mélange de thermoplastiques s’avère prometteur pour en améliorer les propriétés d’usage. Récemment, un procédé de synthèse hydrothermale a permis d’obtenir un hydrogel chargé de nanoplaquettes de talc, ouvrant des perspectives d’élaboration de nanomatériaux à base de talc, potentiellement concurrents de ceux à base d’argile modifié. La grande quantité d’eau, introduite dans les appareils de mise en œuvre à l’état fondu, conduit à une perte de matière minérale importante et à l’agrégation partielle du talc. Ces contraintes rendent obligatoire l’utilisation de la mini-extrudeuse, de faible capacité, pour élaborer ces systèmes multiphasiques innovants, comme les nanocomposites polyamide/talc synthétique ou les mélanges polypropylène/polyamide (PP/PA) chargés de talc synthétique. Dans une phase polaire, le talc synthétique présente une structure constituée majoritairement de nanoparticules, mais aussi d’agrégats formés lors du malaxage. Il a été montré qu’une polarité accrue de la phase polyamide facilitait la nanodispersion du talc synthétique. Dans le cas des mélanges chargés, le talc synthétique est préférentiellement localisé dans les nodules de PA. Pour un polyamide peu polaire, l’effet émulsifiant est amplifié, ce qui s’explique par la rupture des nodules au niveau de zones peu cohésives PA/talc synthétique. D’autre part, l’augmentation de la viscosité de la matrice PP entraîne une localisation partielle du talc synthétique à l’interface matrice/nodules.Les relations structure-rhéologie des systèmes binaires et ternaires ont été discutées. / Addition of clay nanoplatelets within a thermoplastic matrix or immiscible thermoplastic blend usually improves final properties of materials. Recently, a hydrogel containing talc nanoplatelets has been obtained from hydrothermal synthesis, opening possibilities of development of talc based nanomaterials, which could rival the nanocomposites based on organically modified clay.The presence of large amount of water in the mixing chamber leads to significant losses of inorganic matter and to the presence of a few synthetic talc aggregates. These observations require the use of a twin screw mini-extruder which is appropriate to the elaboration of innovative multiphase materials, such as the synthetic talc/polyamide nanocomposites or the synthetic talc/polyamide/polypropylene blends.The structure of nanocomposites based on synthetic talc is mainly composed of nanometric entities, but also of a few micrometric aggregates. It has been shown that an increase of the polarity of the polyamide favours the dispersion of synthetic talc at nanometric scale.In the case of filled blends, the synthetic talc particles are preferentially located within PA nodules. The reduction of nodule size is explained by the breakup of nodules, due to numerous cohesion defects between synthetic talc nanoparticles and polyamide dispersed phase. Moreover, increasing polypropylene matrix viscosity leads to a selective localization of the synthetic talc at the nodule/matrix interface.Relationships between structure and rheology of binary and ternary systems have been discussed.

No description available.

Os polímeros têm sido usados em áreas diferentes, como indústrias automotivas, eletrônicas e de construção civil. A poliamida 6 (PA 6) é um dos principais plásticos de engenharia com aplicações em diversas áreas produtivas, devido as suas propriedades térmicas, mecânicas e a estabilidade dimensional. O objetivo principal deste trabalho foi estudar a potencialidade do uso do dióxido de silício coloidal (SiO2) como carga em substituição ao talco, estudando o efeito da radiação ionizante em suas propriedades. O SiO2 é uma substância amorfa com baixa densidade que tem potencial para ser usado como carga mineral em substituição ao talco na matriz da resina de PA 6. Atualmente o talco é a carga mineral mais utilizada pelas indústrias, por isto vem sofrendo redução de suas reservas ao longo dos anos. Este estudo foi desenvolvido a partir da preparação de um \"masterbeach\" de PA 6 com SiO2. Posteriormente, este \"masterbeach\" foi fracionado em diferentes porcentagens em uma matriz de PA 6. Os corpos de prova das amostras foram processados em uma extrusora dupla rosca, injetados e irradiados no acelerador de elétrons para estudar o efeito da radiação ionizante no compósito de PA 6 com diferentes porcentagens de SiO2. Assim sendo, as propriedades destes compósitos foram analisadas e comparadas com as propriedades das amostras de PA6 com talco. Os resultados mostraram que a utilização do SiO2 como carga para a poliamida 6 é tecnicamente viável, uma vez que suas propriedades foram semelhantes ao compósito de PA 6 com talco. A irradiação dos compósitos estudados apresentou melhorias principalmente nas propriedades térmicas e mecânicas. / Polymers have been used in different fields, such as automotive, civil construction and electronics industries. Polyamide 6 (PA 6) is one of the main engineering plastics with several productive applications areas. By the same token, there was an interest in improving their thermal, mechanical and dimensional stability properties. The main objective of this work was to study the potentiality of colloidal silicon dioxide such as filler. According to literature, SiO2 is an amorphous substance with low density. In addition, this material has the potential to be used as a mineral filler to replace the talc in the PA 6 resin matrix. Therefore, SiO2 load was compared to the mineral filler talc which is currently used by industries. Consequently, their reservations are decreasing all over the years. Indeed, these studies were developed from colloidal silicon dioxide with PA 6 the masterbatch elaboration. In addition, the masterbatch was fractionated in different percentages in a PA 6 matrix. It is important to emphasize that all samples were injected and irradiated by an electrons accelerator. Furthermore, the effect of ionizing radiation on the PA 6 composite in different SiO2 percentages was studied. In short, radiation interacts with the polymer by transferring energy to a polymer chain causing modifications that are interfering with its properties. Thus, the mechanical and thermal properties of these composites were measured. In this manner, the irradiation composite studied in that research brought improvements in the thermal and mechanical properties evaluated. In conclusion, results have shown that the use of colloidal silicon dioxide in polyamide 6 composite is technically feasible load to replace talc.

Polypropylene continues to be the mainstream choice thermoplastic for automotive applications. In many applications PP is filled with mineral fillers for improvement of properties. Biobased natural fillers or fibres are attractive materials to reduce the weight because of the low specific gravity of the biobased materials compared to the mineral fillers. Our group has done extensive research on the development of wheat straw fiber in thermoplastics in the past years. It is very important to understand the behaviour of single fillers on composites before studying the effects of mixing fillers or fibers (hybridization). The objective of this study is to evaluate and compare systematically the effects of wheat straw and mineral fillers in the polypropylene matrix. The study includes two types of wheat straw (WS) categorized based on their size (fine WS and medium WS) and three different types of natural minerals (Talc, Mica and Wollastonite). Three types of polypropylene (PP), Homopolymer PP, High Impact Copolymer PP and Homopolymer-Copolymer Blend PP, were investigated as the matrix. This study also evaluates the effect of combining two fillers (WS and mineral filler) in the hybrid composite. The fillers were formulated in three different percentages (20, 30 and 40wt %) and compounded via extrusion. Samples for all formulations were prepared by injection molding. The mechanical properties (flexural modulus and strength, tensile modulus and strength, impact strength), water absorption and density were measured. The properties of hybrid composites were evaluated by varying the amounts of two fillers at 10wt%-20wt%, 15wt%-15wt% and 20wt%-10wt% each, keeping the overall filler content constant at 30wt%. The effect of type of filler, filler size and filler content were critical in this work. The results obtained from this study indicated that filler type and filler content greatly influenced the mechanical properties and water absorption characteristics of the composites. The flexural modulus increased with increasing filler content. It was interesting to observe that though the impact strength decreased with the addition of fillers, increasing the filler content from 20 to 40 wt% did not affect the property. With respect to all fillers, wollastonite improved the mechanical properties significantly. Increasing the amount of WS content reduced the composite’s resistance to water absorption. Among mineral fillers, mica showed significantly higher percentage gain in weight with water absorption. Combination of fillers at varying percentages did not have any synergy effect on the mechanical behaviour of the composite. The percentage increase in weight with water absorption was observed to be increasing with increasing WS content in hybrid composites, but significantly lower than pure WS composites. The morphological study on WS composites revealed improved interaction of filler with homopolymer and polypropylene blend.