15 research outputs found

    Novel monomers with N-methyl-D-glucamine segments and their application in structured porous materials for arsenic capture

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    The N-methyl-D-glucamine moieties exhibit high ability and selectivity toward arsenate ions in water by a complexation mechanism that involves their hydroxyl groups. In this work, the syntheses of two monomers containing N-methyl-D-glucamine, namely 4-vinylbenzyl-N-methyl-D-glucamine (VbNMDG), and N-methyl-D-glucamine methacrylamide (MNMDG) were studied. Different synthetic routes were considered in order to obtain liquid monomers able to polymerize and selectively capture arsenic. Furthermore, the incorporation of protective groups like trimethylsilyl moieties in the molecular structure was assessed to prevent transfer reactions during further polymerization. After polymerization, hydroxyl groups were deprotected using hydrofluoric acid. Following this methodology, structured microporous polymeric films based on colloidal crystal templates were prepared. NMR and FTIR techniques were used to follow the reactions and to determine the chemical structure of the obtained products. The morphology of materials was characterized by SEM. The performances of the developed polymeric films to selectively capture arsenic were determined. Films showed an improved and reproducible sensitivity to arsenic detection exhibiting high values of arsenic capturing capability (around 90%)

    Uma revisão sobre polimerização de olefinas usando catalisadores Ziegler-Natta heterogêneos

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    Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling

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    A mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. Special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. The thermodynamic model is based on a cubic equation of state and a mixing rule applied to the low-pressure vapor-liquid equilibrium of polymeric solutions, suitable for modeling the auto-refrigerated polymerization reactors, which use the vaporization rate to remove the reaction heat from the exothermic reactions. The simulation results show the high predictive capability of the proposed model when compared with plant data for conversion, average molecular weights, polydispersity, melt flow index, and thermal properties for different polymer grades
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