No description available.

Flax fibers can be used as environmentally friendly alternatives to conventional reinforcing fibers (e.g., glass) in composites. The interest in natural fiber-reinforced polymer composites is growing rapidly due to its high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. These advantages place natural fiber composites among the high performance composites having economic and environmental advantages. In the field of technical utilization of plant fibers, flax fiber-reinforced composites represent one of the most important areas. On the other hand, lack of good interfacial adhesion and poor resistance to moisture absorption make the use of natural fiber-reinforced composites less attractive. In order to improve their interfacial properties, fibers were subjected to chemical treatments, namely, mercerization, silane treatment, benzoylation, and peroxide treatment. Selective removal of non-cellulosic compounds constitutes the main objective of the chemical treatments of flax fibers to improve the performance of fiber-reinforced composites. The objective of this study was to determine the effects of pre-treated flax fibers on the performance of the fiber-reinforced composites. Short flax fibers were derived from Saskatchewan-grown flax straws, for use in fiber-reinforced composites. Composites consisting of high-density polyethylene (HDPE) or linear low-density polyethylene (LLDPE) or HDPE/LLDPE mix, chemically treated fibers and additives were prepared by the extrusion process. Extrusion is expected to improve the interfacial adhesion significantly as opposed to simple mixing of the two components. The extruded strands were then pelletized and ground. The test samples were prepared by rotational molding. The fiber surface topology and the tensile fracture surfaces of the composites were characterized by scanning electron microscopy to determine whether the modified fiber-matrix interface had improved interfacial bonding. Mechanical and physical properties of the composites were evaluated. The differential scanning calorimetry technique was also used to measure the melting point of flax fiber and composite. Overall, the scanning electron microscopy photographs of fiber surface characteristics and fracture surfaces of composites clearly indicated the extent of fiber-matrix interface adhesion. Chemically treated fiber-reinforced composites showed better fiber-matrix interaction as observed from the good dispersion of fibers in the matrix system. Compared to untreated fiber-reinforced composites, all the treated fiber-reinforced composites had the same tendency to slightly increase the tensile strength at yield of composites. Silane, benzoylation, and peroxide treated fiber-reinforced composites offered superior physical and mechanical properties. Strong intermolecular fiber-matrix bonding decreased the high rate of water absorption in biocomposites. The incorporation of 10% untreated or chemically treated flax fibers also increased the melting point of composites. Further investigation is required to address the effect of increase in fiber content on the performance of composites.

Flax fibers can be used as environmentally friendly alternatives to conventional reinforcing fibers (e.g., glass) in composites. The interest in natural fiber-reinforced polymer composites is growing rapidly due to its high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. These advantages place natural fiber composites among the high performance composites having economic and environmental advantages. In the field of technical utilization of plant fibers, flax fiber-reinforced composites represent one of the most important areas. On the other hand, lack of good interfacial adhesion and poor resistance to moisture absorption make the use of natural fiber-reinforced composites less attractive. In order to improve their interfacial properties, fibers were subjected to chemical treatments, namely, mercerization, silane treatment, benzoylation, and peroxide treatment. Selective removal of non-cellulosic compounds constitutes the main objective of the chemical treatments of flax fibers to improve the performance of fiber-reinforced composites. The objective of this study was to determine the effects of pre-treated flax fibers on the performance of the fiber-reinforced composites. Short flax fibers were derived from Saskatchewan-grown flax straws, for use in fiber-reinforced composites. Composites consisting of high-density polyethylene (HDPE) or linear low-density polyethylene (LLDPE) or HDPE/LLDPE mix, chemically treated fibers and additives were prepared by the extrusion process. Extrusion is expected to improve the interfacial adhesion significantly as opposed to simple mixing of the two components. The extruded strands were then pelletized and ground. The test samples were prepared by rotational molding. The fiber surface topology and the tensile fracture surfaces of the composites were characterized by scanning electron microscopy to determine whether the modified fiber-matrix interface had improved interfacial bonding. Mechanical and physical properties of the composites were evaluated. The differential scanning calorimetry technique was also used to measure the melting point of flax fiber and composite. Overall, the scanning electron microscopy photographs of fiber surface characteristics and fracture surfaces of composites clearly indicated the extent of fiber-matrix interface adhesion. Chemically treated fiber-reinforced composites showed better fiber-matrix interaction as observed from the good dispersion of fibers in the matrix system. Compared to untreated fiber-reinforced composites, all the treated fiber-reinforced composites had the same tendency to slightly increase the tensile strength at yield of composites. Silane, benzoylation, and peroxide treated fiber-reinforced composites offered superior physical and mechanical properties. Strong intermolecular fiber-matrix bonding decreased the high rate of water absorption in biocomposites. The incorporation of 10% untreated or chemically treated flax fibers also increased the melting point of composites. Further investigation is required to address the effect of increase in fiber content on the performance of composites.

No description available.

Once current nuclear reactor operation ceases in the U.K. there will be an estimated 99,000 tonnes of irradiated nuclear graphite waste which may account for up to 30% of any future UK geological ILW disposal facility [1]. In order to make informed decisions of how best to dispose of such large volumes of irradiated graphite (I-graphite) within the UK nuclear programme, it is necessary to understand the nature and migration of isotopes present within the graphite structure. I-graphite has a combination of short and long term isotopes such as 14C, 3H and 36Cl, how these behave prior to and during disposal is of great concern to scientific and regulatory bodies when evaluating present decommissioning options. Various proposed decontamination and immobilisation treatments within the EU Euroatom FP7 CARBOWASTE program have been explored [2, 3]. Experiments have been carried out on UK irradiated British Experimental Pile Zero and Magnox Wylfa graphite in order to remove isotopic content prior to long term storage and to assess the long term leachability of isotopes. Several leaching conditions have been developed to remove 3H and 14C from the irradiated graphite using oxidising and various acidic environments and show mobility of 3H and 14C. Leaching analysis obtained from this research and differences observed under varying leaching conditions will be discussed. Thermal analysis of the samples pre and post leaching has been performed to quantify and validate the 14C and 3H inventory. Finally the research objectives address differences in leachability in the graphite to that of structural and operational variation of the material. Techniques including X-ray Tomography, Scanning Electron Microscopy, Autoradiography and Raman spectroscopy have been examined and show a significant differences in microstructure, isotope distribution and location depending of irradiation history, temperature and graphite source. Ultimately the suitability of the developed chemical treatments will be discussed as whether chemical treatment is a viable option prior to irradiated graphite long term disposal.

Este estudo teve o objetivo de avaliar, por meio do ensaio de microtração, o efeito na resistência adesiva e no modo de fratura da Y-TZP quando cimentada a blocos padronizados de resina composta com um cimento resinoso autoadesivo (RelyX Unicem 3M ESPE, Saint Paul/ Minnesota, EUA), sob diferentes tratamentos de superfície, antes e após o envelhecimento. Doze amostras de Y-TZP foram divididas em seis grupos, de acordo com os seguintes tratamentos de superfície: Ru (sem tratamento de superfície); Ap (Alloy Primer); Zp (Z-Prime Plus); Na (solução de hidróxido de sódio - NaOH); NaAp (solução de NaOH, seguida pela aplicação de Alloy Primer); NaZp (NaOH, seguida pela aplicação de Z-Prime Plus). Após os tratamentos de superfície e a cimentação, de acordo com as recomendações do fabricante, os blocos foram armazenados por 24h em água destilada e cortados em seguida. O teste de microtração aconteceu em dois momentos: 72h após os procedimentos de corte e após seis meses de envelhecimento (E). Ao final do teste de microtração, os espécimes foram analisados em estereomicroscópio e no microscópico eletrônico de varredura (MEV), para caracterização do modo de fratura. A distribuição Weibull a dois parâmetros (Synthesis 9, Weibull ++; Reliasoft, Tucson, AZ, USA) foi utilizada para cálculo da probabilidade de sobrevida em função da resistência adesiva em 10 MPa, 15 MPa e 20 MPa. A comparação entre os grupos também foi realizada com o módulo de Weibull e a resistência característica (resistência adesiva). As resistências adesivas imediatas e após o envelhecimento foram: (Ru 15,26 MPa e RuE 12,15 MPa; Ap 13,82 MPa e ApE 10,72 MPa; Zp 14,19 MPa e ZpE 9,72 MPa; Na 17,92 MPa e NaE 13,15 MPa; NaAp 21,25 MPa e NaApE 18,13 MPa; NaZp 16,25 MPa e NaZpE 8,66 MPa). Nos grupos imediatos, a utilização da solução básica, sozinha ou associada aos primers, apresentaram maior quantidade de falhas mistas, porém, após o envelhecimento, as falhas adesivas foram mais frequentes para esses tratamentos. Através dos resultados obtidos, pôde-se concluir que a solução de NaOH associada ao Alloy Primer, foi o único tratamento de superfície que apresentou os maiores valores de resistência adesiva, antes e após o envelhecimento, apresentando modo de fratura predominantemente mista. O tempo de armazenamento levou a uma redução da probabilidade de sobrevida em função da carga de 10 MPa e 15 MPa para todos os tratamentos, exceto para o NaAp. / This study aimed to evaluate, through microtensile test, the effect of bond strength and fracture modes of the Y-TZP when it is cemented to a standard composite resin blocks with a self-adhesive resin cement (RelyX Unicem - 3M ESPE, Saint Paul / Minnesota, USA) under different surface treatments before and after aging. Twelve samples of Y-TZP were divided into six groups, according to the following surface treatments: Ru (no surface treatment); Ap (Alloy Primer); Zp (ZPrime Plus); Na (sodium hydroxide solution - NaOH); NaAp (NaOH solution, followedby Alloy Primer); NaZp (NaOH solution, followed by Z-Prime Plus). After the surface treatment and cementation, according to the manufacturer\'s recommendations, the blocks were stored for 24 hours in distilled water and then cut. The microtensile testing was performed in two times: 72 hours after the cutting procedures and after six months of aging (E). At the end of microtensile test, the specimens were analyzed in stereomicroscope and scanning electron microscope (SEM) to characterize the fracture mode. The 2-parameter Weibull distribution (Synthesis 9, Weibull ++; Reliasoft, Tucson, AZ, USA) was used to calculate the survival probability function of the adhesive strength at 10 MPa, 15 MPa and 20 MPa. Comparisons between groups were also analysed with Weibull modulus and characteristic strength (bond strength). Results showed that the immediate and after aging bond strength were: (Ru 15.26 MPa and RuE 12.15 MPa; Ap - 13.82 MPa and ApE - 10.72 MPa; Zp - 14.19 MPa and ZpE - 9.72 MPa; Na - 17.92 MPa and NaE - 13.15 MPa; NaAp 21.25 MPa and NaApE - 18.13 MPa; NaZp 16.25 MPa and NaZpE - 8.66 MPa). In the immediate groups, using the basic solution, alone or in association with primers the results showed an increased amount of mixed failures, but after aging, the adhesive failures was more frequent for such treatments. It was possible to conclude that the NaOH solution associated with the Alloy Primer was the only surface treatment that showed the highest bond strength values before and after aging, with predominantly mixed fracture mode. The storage time promoted a reduction in survival probability function load of 10 MPa and 15 MPa for all treatments except for the NaAp.

Dentre os resíduos da agroindústria brasileira, a vinhaça, efluente da produção de etanol, se destaca por ser produzida em grande volume e ser altamente poluente. Por apresentar elevada concentração de nutrientes, sua principal aplicação tem sido a fertirrigação da lavoura canavieira, prática que pode causar impactos adversos ao solo e recursos hídricos. Uma alternativa promissora é sua utilização como meio de cultura na produção de biomassa de microalgas, as quais produzem lipídios conversíveis a biodiesel, sendo necessária a redução da concentração de partículas causadoras de cor e turbidez, proporcionando melhoria das condições de entrada de luz nos fotobiorreatores. Nesse sentido, o presente trabalho propôs a utilização das técnicas de coagulação, floculação e sedimentação para a clarificação da vinhaça, visando sua adequação ao cultivo de microalgas. Na etapa I foram investigados os coagulantes cloreto férrico, sulfato de alumínio, hidróxido de cálcio, tanino e cinco polímeros sintéticos, em diferentes concentrações e faixas de pH, visando-se as maiores remoções de cor e turbidez. Nas dosagens empregadas, os coagulantes cloreto férrico e sulfato de alumínio não apresentaram desempenho satisfatório. Os melhores resultados foram obtidos com o uso do polímero catiônicoLAB TAE 409, o qual proporcionou reduções de 22% da cor e 78% da turbidez (com relação à vinhaça pré-centrifugada), mesmo em baixas dosagens (20 mg/L). Na etapa II foram realizados ensaios em jarteste, onde foram determinados a melhor temperatura (30ºC), a dosagem de polímero LAB TAE 409 (20 mg/L), o pH (~4,70, sem ajuste) e os parâmetros de mistura e sedimentação (TML = 5 min, GML = 60 s-1 e VSED = 1 cm/min), os quais proporcionam as maiores reduções de cor (76%) e turbidez (96%), com relação à vinhaça bruta. A partir do melhor tratamento definido na etapa II, a vinhaça foi empregada como meio para o cultivo da microalga Chlorella vulgaris (etapa III), conforme seguintes proporções: V1 (90% vinhaça tratada / 10% inóculo), V2 (45% vinhaça tratada / 45% água deionizada / 10% inóculo), V3 (5% vinhaça tratada / 85% água deionizada / 10% inóculo), comparados ao cultivo em meio padrão WC. Embora menores que os crescimentos (biomassa) obtidos no cultivo em meio padrão WC, os meios constituídos de vinhaça pré-tratada proporcionaram crescimento de Chlorella vulgaris, com velocidades específicas de crescimento próximas ao meio WC, indicando seu potencial uso na obtenção de biomassa dessa espécie de microalga. / Among the brazilian agro-industrial residues, vinasse, effluent from ethanol production, stands out for being produced in large volume and can be highly pollutant. Presenting high concentration of nutrients, its main application has been the irrigation of sugarcane, a practice that may cause adverse impacts to soil and water resources. A promising alternative is to use the vinasse as the culture medium for microalgal biomass production, which produce lipids convertible to biodiesel. Therefore, it is required an adaptation to this type of cultivation, mainly, through the reduction of the concentration of particles that cause turbidity and color, providing improved lighting conditions in photobioreactors. In this way, this work proposed the use of the coagulation, flocculation and sedimentation techniques for clarifying vinasse, aiming the cultivation of microalgae. In step I were investigated the coagulants ferric chloride, aluminum sulfate, calcium hydroxide, tannin and five synthetic polymers, at different concentrations and pH ranges, aiming at the highest color and turbidity removal. In the dosages investigated, ferric chloride and aluminum sulfate did not show satisfactory performance. The best results were obtained with use of the cationic polymer LAB TAE 409, which provided a 22% reduction of color and 78% of turbidity (relative to vinasse pre-centrifuged), even at low dosages (20 mg/L). In step II, tests were carried out in jartest, which were determined the best temperature (30 ºC), the polymer LAB TAE 409 dosage (20 mg/L), pH (~ 4.70, without adjustment), and the mixing and sedimentation parameters (TML = 5 min, GML = 60 s-1 VSED = 1 cm/min), which provided the major reductions in color (76%) and turbidity (96%), relative to the raw vinasse. From the best treatment defined in step II, vinasse was used as medium for the cultivation of microalgae Chlorella vulgaris (stage III), according to the following proportions: V1 (90% treated vinasse / 10% inoculum), V2 (45% vinasse treated / deionized water 45% / 10% inoculum), V3 (5% vinasse treated / deionized water 85% / 10% inoculum), compared to standard WC medium. Although lower than the growths (biomass) obtained in culture using WC, the mediums with pretreated vinasse have provided the growth of Chlorella vulgaris, with specific growth rates near the WC medium, indicating its potential use for obtaining this microalgal biomass.

Physical property data was used to test two hypotheses pertaining to the impact of a chemical pre-treatment on the qualities of low consistency refined pulp. The first objective was to determine whether the addition of a chemical treatment would effectively accelerate the refining process when compared to a regular pulp. This involved the measurement of the physical property data and how it changed with increased refining energy. The second objective was to determine how the chemical treatment affected fibre development during refining, and whether its implementation could result in enhancement of inter-fibre bondability. Theoretical models for the physical properties of paper were used to study the fibre-to-fibre bonding properties of the tested paper samples. Additionally, SEM images were obtained to study the deferences in morphology of the tested pulp samples.

Physical property data was used to test two hypotheses pertaining to the impact of a chemical pre-treatment on the qualities of low consistency refined pulp. The first objective was to determine whether the addition of a chemical treatment would effectively accelerate the refining process when compared to a regular pulp. This involved the measurement of the physical property data and how it changed with increased refining energy. The second objective was to determine how the chemical treatment affected fibre development during refining, and whether its implementation could result in enhancement of inter-fibre bondability. Theoretical models for the physical properties of paper were used to study the fibre-to-fibre bonding properties of the tested paper samples. Additionally, SEM images were obtained to study the deferences in morphology of the tested pulp samples.

A empresa estudada está sediada em Porto Alegre, RS, Brasil, e fabrica produtos de limpeza. Os efluentes provêm das águas de lavagens dos tanques e misturadores de produção, recipientes utilizados na separação de matérias-primas e da lavagem do próprio piso da fábrica, onde ocorrem derramamentos de produtos. Foi implantada uma estação de tratamento de efluentes que opera por processos físico-químicos de coagulação/floculação e adsorção. Entretanto, observou-se que era ineficiente para atender aos parâmetros de qualidade de água exigidos pela legislação. Assim, o objeto deste estudo foi minimizar a geração de efluentes e aperfeiçoar a operação da estação de tratamento dos efluentes líquidos da empresa. A metodologia de trabalho consistiu na caracterização do efluente industrial; monitoramento do desempenho da estação de tratamento de efluentes, implantação de mudanças no processo produtivo para verificar a possibilidade de minimização da geração de efluentes bem como da carga poluidora, e estudo de alternativas de tratamento para melhorar a qualidade da água. Os parâmetros avaliados foram pH, DQO, DBO, fósforo total, nitrogênio total, óleos e graxas, surfactantes, sólidos sedimentáveis e sólidos suspensos. Os resultados demonstram que o efluente apresenta pH alcalino, uma elevada carga orgânica, é rico em nitrogênio e fósforo e possui uma alta concentração de surfactantes. Entretanto, a implantação de um sistema de produção mais limpo, através da programação prévia do processo produtivo, e aplicação de novos procedimentos durante as operações de envase, permitiu que o volume de efluentes gerados diminuísse de 8 m3/dia para 6 m3/dia. A carga de poluente na ETE baixou significativamente, resultando em maior eficiência da estação de tratamento de efluentes. Assim, foi possível atingir, exata ou aproximadamente, todos os parâmetros de emissão padrão. O estudo das alternativas de tratamento também comprovou que o tratamento físicoquímico de coagulação/floculação é mais eficiente quando seguido de um tratamento de adsorção por carvão ativado. A fotocatálise heterogênea, com aplicação de luz UV como forma de polimento ao efluente, reduz substancialmente a quantidade de matéria orgânica e surfactantes presentes no efluente. Os valores da relação DBO/DQO, para o efluente tratado, que variam de 0,29 a 0,34, demonstram a possibilidade de degradação biológica, desde que haja aclimatação ou indução dos microrganismos. Esse fato abre a possibilidade de realizar o tratamento biológico do efluente industrial, misturado ou não ao esgoto cloacal gerado na empresa. / The company studied produces cleaning reagents and is located in Porto Alegre, RS, Brazil. The effluent comes from many washing operations, including equipment and ground cleaning. A physical-chemical treatment plant was installed. It is based on coagulation/flocculation and activated carbon adsorption. However, the treatment operation did not reach the water quality emission standards established by the legislation. Thus, the aim of this work was to minimize the effluent generation and to improve the effluent treatment plant efficiency. The methodology consisted of characterization of the industrial effluent, evaluation of effluent treatment plant, implantation of clean technology procedures and the study of new alternatives for water quality improvement. The parameters analyzed were pH, DQO, DBO, total phosphorous, total nitrogen, oils and greases, surfactants, settable solids, and suspended solids. The results showed that the effluent presents an alkaline pH, a high organic load, is rich in nitrogen and phosphorous, and presents a high concentration of surfactants. However, the implantation of clean technology procedures, by process programming and employees training, allowed a volume reduction from 8 m3/day to 6 m3/day. The load of pollutants was significantly reduced, allowing a better performance of the effluent treatment plant. The emission treatment reached, or became very near the standard. The study of new alternatives also proved that the physical-chemical treatment of coagulation/flocculation is more efficient when followed by an activated carbon adsorption treatment. The use of the TiO2 – photocatalysis process – reduced surfactants concentration in effluent. The BOD/COD relationship, ranged from 0,29 to 0,34, showed that biological degradation is possible, provided that there is microorganism acclimatizing. This fact allows the possibility for the biological treatment of the industrial effluent to be either dumped into the general sewage generated in the company or not.