ABSTRACT An asymmetric membrane of polysulfone (PSf) was synthesized by phase inversion method. Permeation experiments were carried out between 2 to 5 bar pressure, and at temperatures 20 to 45°C. The dense-selective layer of PSf membrane presents regular thickness (about 5 µm), and was not possible to observe the formation of macrovoids in porous layer. The CO2 permeability through membrane was 18.8 Barrer at 35°C and 2 bar pressure, and this relationship between the pressure and the CO2 permeability was described adequately by Dual-mode model. The absence of CH4 permeability at 2 and 3 bar pressure, qualifies the PSf membrane for gases separation with high selectivity in this range.

Oil is a major pollutant of water resources, affects aquatic life, causing environmental degradation. Currently there is an increase in studies of membrane applied to separation of oil-water. Among these membranes, there are composite membranes, which show as main characteristic an association of organic and inorganic membrane properties. In a tangential flow process, the ceramic tube (support) is responsible for the mechanical strength of the membrane and the selective barrier property of the membrane is established by the polymer. The aim of this work is the application of α-alumina/polyamide 66 composite membrane in the retention of sunflower oil from oil-water emulsions and the study of resistance of such membranes in ultrafiltration processes. The α-alumina ceramic tubes were impregnated internally with a solution of polyamide 66 (PA66) (5% w/v) and tested with distilled water and sunflower oil solutions at concentrations of 50, 100 and 200 mg·L-1. Membranes impregnated with PA66 showed a sunflower oil retention between 53.5 and 99.5% and superior membrane resistance (MR) to the permeate flux (1.92 x 1013 a 5.52 x 1013) which explains the decrease in the permeate volume.

This paper aims the morphological and structural characterization of ceramic membranes of mullite and their application in the removal of Escherichia coli. A complex irregular structure presented by the pores of the membrane was verified by scanning electron microscopy (SEM). The average pore size and distribution were determined by mercury intrusion porosimetry. The average pore size of the material presented was 0,39 µm. Microfiltration tests resulted in a protein retention of 46, 76 and 89% for trypsin (TR), egg albumin (EA) and bovine serum albumin (BSA), proving the efficiency of the membrane microfiltration tests for molecular weight of 69 kDa. The application of the membranes on the retention of gram-negative bacterium E. coliresulted in a 66% efficiency at a pressure of 200 kPa and a 98% efficiency when applied a pressure of 50 kPa. Therefore, the use of mullite membranes show limited efficiency towards bacteria retention. Nevertheless, they present fluxes similar to other materials proposed in the literature.

In this work, a protocol for the formulation of an enzyme concentrated product to be applied in fruit juice treatment is described. Downstream processing conditions for the recovery and concentration of pectinases produced by the new strain Aspergillus niger LB-02-SF in solid state cultivation were assessed. The solid-liquid ratio in the extraction step of pectinases recovery from the cultivated media was evaluated and the highest activity was obtained with a solid-liquid ratio of 1:10. The crude extract was concentrated by ultrafiltration and the total pectinase (TP) activity was 73.6-fold concentrated in relation to the crude extract, and a final TP titer of 663 U mL–1 was obtained with 73.7% of recovery yield. KCl and different glycerol concentrations were added to the concentrated extract and the stability of pectinases during the storage at 5°C for 59 weeks was tested. The formulation with 50% w/w glycerol was applied to the treatment of apple and grape juices and the results of these tests were statistically comparable to those obtained with two high-quality commercial preparations.

This study aims to evaluate the influence of pro-oxidant additive and accelerated aging on the degradation of polyethylene (PE) samples in simulated soil, in accordance with ASTM G160-03. Films of polyethylene with and without pro-oxidant additive were studied, before and after 72 hours of accelerated aging. The films were initially characterized by analyses of Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) (to evaluate the Carbonyl Index (CI)). The films were exposed for 30, 60 and 90 days in simulated soil, with controlled moisture and soil pH. The results showed the degradation of polyethylene films through an increase of CI in samples with additive and accelerated aging after 30 days of exposure, and a decrease, after 60 and 90 days, indicating the uptake of material oxidation by-products by microorganisms. The polyethylene films without pro-oxidant additive after accelerated aging showed greater structural and surface modifications, as compared to films with the additive.

Cellulose acetates (CA) with different degrees of acetylation were synthesized from cellulose extracted from corn stover. Membranes were prepared for the ultrafiltration process with pure polymers and blend form of CA utilizing a dioxane/acetone system. The membranes were characterized according to their transport properties. The blend form materials presented the best results for application in ultrafiltration experiments. M-TAC/DAC (corn stover triacetate and diacetate) and M-TAC/DAC-Rho (corn stover triacetate and Rhodia diacetate) presented rejection to egg albumin protein of 87.39% and 80.50%, respectively. Thus, MWCO of 45 kDa was determined for these materials.

The aim of this paper was to prepare a poly (vinylidene fluoride) (PVDF) membrane using different non-solvents in the coagulation bath for the phase inversion method. In order to increase the mechanical strength of membranes, facing the pressure of work, was used a macro-porous polyester support. The morphology and structure of the resulting membranes were evaluated by scanning electron microscopy, porosity measurements, water and 1-octanol uptake, contact angle, pure water flux, hydraulic permeability and hydraulic resistance. The morphology and pure water flux changed significantly using ethanol (symmetric membrane) and/or water (asymmetric membrane) as the non-solvent. The symmetric membrane presented a high hydrophobic surface (water contact angle ~136º) and a higher pure water flux and porosity than the asymmetric membrane, which presented a lower hydrophobicity surface (water contact angle ~90º). The morphologies obtained suggest different applications.

In this study, thermoplastic polyurethanes (TPUs) were synthesized using the one-shot process in solution. To obtain the samples n-phenylaminopropyl polyhedric oligomeric silsesquioxane (POSS) was added as a chain modifier during the synthesis in four different amounts. The samples were characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and capillary rheometry. FTIR confirm the TPU attainment due the absence of the band at ~2253 cm-1 suggesting a complete conversion of the isocyanate terminations. The TGA showed that incorporation of POSS decreased the rate of mass loss of TPU under isothermal conditions. The flexible phase showed an enhanced stability to temperature, probably due to increased phase separation between the rigid and flexible domains. The DSC showed that incorporation of 0.4 wt. (%) of POSS increased the glass transition temperature of the flexible phase. Moreover, addition of POSS modified the melting behaviour, providing samples with a higher melting enthalpy compared to neat TPU as a consequence of the formation of larger crystals. The capillary rheometry analysis revels that the POSS addition showed a clear tendency toward higher intrinsic viscosities as the amount of POSS was increased.

Cellulose acetate produced from mango seed fibers cellulose was used as a matrix for preparation of microparticles empty and load with acetaminophen (Paracetamol) in order to evaluate the incorporation of an active agent during the formation of microparticles. The microparticles are characterized by Fourier Transformed Infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). The incorporation of paracetamol can be confirmed by the change in value of glass transition temperature (Tg). The formation of microparticles spherical was observed by SEM and showed an average diameter of 1.010 and 0.950 mm for empty and load microparticles respectively.

O poli(cloreto de vinila) (PVC) é um dos polímeros utilizado no campo das embalagens e no setor calçadista, e, em função da sua aplicação diversificada, apresenta elevados percentuais em aterros domésticos e industriais. É um polímero amorfo podendo apresentar diferentes teores de plastificante e outros aditivos responsáveis pela sua estabilização, os quais podem influenciar no tempo de vida útil e nas propriedades do produto final. Este trabalho apresenta o estudo da degradação química e biológica de filmes de poli(cloreto de vinila) flexível (PVC-f), no aterro sanitário São Giácomo, na cidade de Caxias do Sul/RS, antes e após 330 dias de disposição. As amostras de PVC-f antes e após a disposição no aterro sanitário foram avaliadas por análise térmica (TGA), estrutural (FT-IR) e morfológica (MEV e MO). Observou-se que as amostras de PVC-f dispostas no aterro sanitário (PVC-fa), apresentam um único evento de perda de massa, em relação ao PVC-f não degradado ou virgem (PVC-fv), além de um maior % de perda de massa e de mudanças estruturais. Nas amostras de PVC-fa foram observadas modificações morfológicas importantes para descrever os fenômenos de degradação como erosão da superfície, bioerosão, que propiciaram a ação das leveduras, bactérias e fungos presentes no meio no polímero aterrado.

The poly (vinyl chloride) (PVC) is one of the polymers used in the field of packing materials and footwear sector, and due its diversified applications, it has presented in a high percentage of domestic and industrial landfills It is an amorphous polymer and may present different levels of plasticizer and other additives responsible for its stabilization, which can influence the lifetime and the properties of the final product. This work presents the study of the chemical and biological degradation of poly (vinyl chloride) flexible (PVC-f) films, at São Giácomo landfill, in Caxias do Sul city after 330 days of disposition. The samples of PVC-f were evaluated by thermal (TGA), structural (FT-IR) and morphological (MEV and MO) analysis after disposition. Samples of PVC-f disposed to landfill (PVC-fa) showed a single event of weight loss, when compared to PVC-f undegraded or virgin (PVC-fv), besides a higher weight loss and structural changes. In the PVC-fa samples, morphological modifications were observed, which are very important to describe the degradation phenomenon as superficial erosion and bioerosion, which propitiated the action of the yeast, bacteria and fungi present in the environment on the disposed polymer.

O poli(fluoreto de vinilideno) (PVDF) é um polímero semicristalino contendo uma fase amorfa e uma cristalina. Essa característica é importante para o preparo de membranas assimétricas, pois a fase cristalina tem grande influência na formação da estrutura da membrana e a fase amorfa na porosidade. Membranas de PVDF foram preparadas pelo processo de inversão de fases e avaliadas quanto à permeabilidade e morfologia, bem como o efeito do tratamento térmico. Foram comparadas as seguintes membranas: membrana sem tratamento térmico, membrana com tratamento térmico e membrana comercial. Ensaios de resistência química, fluxo permeado de água a várias pressões, difusão de íons, Microscopia Eletrônica de Varredura (MEV), Calorimetria Exploratória Diferencial (DSC) e Análise Termogravimétrica (TGA) foram realizados para verificar o comportamento das membranas.

Poly(Vinylidene Fluoride) (PVDF) is a semicrystalline polymer containing an amorphous and a crystalline phase. This characteristic is important for the preparation of asymmetric membranes, because the crystalline phase has great influence on the membranes structure, while the amorphous phase affects the porosity. PVDF membranes were prepared by the phase inversion process, which were then evaluated with regard to permeability and morphology, as well as the thermal treatment effect. The following membranes were compared: without thermal treatment, with thermal treatment and commercially-available membrane. The analysis of chemical resistance, water permeability flux to different pressures and diffusion of ions, in addition to studies with Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA), were performed to investigate the membranes properties.

This paper compares the thermal stability of the sawdust of different wood species, an important factor in producing reinforced polymers. The compositions of two wood species, Pinus taeda and Eucalyptus grandis, were determined to evaluate the influence of the main wood components on the thermal stability of this material. The two species were submitted to thermogravimetric analysis at different heating rates to calculate the activation energy (Ea) using the Flynn-Wall-Ozawa (FWO) and Kissinger methods. The results suggest that larger quantities of holocellulose and lignin associated with lower extractive contents give the wood greater thermal stability. The Ea values calculated for the two species were in the range of 146-165 kJ.mol-1. Evaluation of the activation energy values offers a simplified means to better understand the thermal decomposition of the sawdust of different wood species used in developing composites.

This article describes the application of software tools to investigate the degradation /biodegradation of the commodity polymer polypropylene (PP) in the sanitary filling of Sao Giacomo in Caxias Do Sul, RS. A description is given of the sanitary filling, in addition to the physicochemical variables that are relevant for the process. The data are organized in matrices and a Principal Component Analysis (PCA) algorithm is applied to interpret the variables correlated with the degradation and biological activity. For analyzing the data, use was made of the tools Matlab and InfoStat, with the purpose of establishing the physicochemical parameters involved in the degradation/biodegradation, and for determining the correlated components in order to predict the behavior of the parameters and the polymer degradation in the sanitary filling. The PCA analysis allowed one to describe the structure and interrelations of the original variables for the biodegradation of organic matter. The important parameters were found to be DQO and DBO which measure biodegradability and ammoniac nitrogen, an indicative of biological activity.

El presente artículo describe la aplicación de herramientas de software al estudio de degradación/biodegradación de polímeros commodity polipropileno (PP) en el relleno sanitario de São Giacomo de Caxias do Sul, RS. Se hace inicialmente una descripción del relleno sanitario, luego se describen las variables fisicoquímicas que intervienen en el proceso, se organizan las matrices de datos y se aplica el algoritmo PCA para interpretar las variables correlacionadas con la degradación y la actividad biológica. En el análisis de los datos multivariados se usaron las herramientas Matlab, InfoStat, con el fin de establecer los parámetros fisicoquímicos involucrados en la degradación/biodegradación, y determinar los componentes correlacionados con el fin de poder predecir el comportamiento de los parámetros y la degradación del polímero en el relleno sanitario. El análisis de componentes principales (PCA) permitió la reducción de 12 variables del 2 componentes principales que muestram a correlación de las variables. Los parámetros importantes son: relación DBO/DQO que miden la biodegradabilidad y nitrógeno amoniacal un indicativo de actividad biológica. Los resultados del análisis PCA describen la estructura y las interrelaciones de variables originales en el fenómeno de biodegradación de la materia orgánica a través del análisis e interpretación de los componentes principales.

Expanded poly(butadiene-co-styrene) (SBR), a residue of the shoe industry of Rio Grande do Sul, is a crosslinked material. For further utilization in recycling and reclaiming processes this residue was ground under ambient conditions. The obtained powder (SBR-r) was physically, thermally and chemically characterized and the results were analyzed as for its suitability for reuse methods. This characterization provides a better understanding of the SBR residue components, which may lead to economic and environmental advantages. The SBR-r (3548 mesh) is composed by 22.2% of SBR and 77.8% of filler. The elastomeric fraction has 71.4% of crosslinked material. The results demonstrate that SBR can be recycled for use in microcellular composites.

Neste trabalho, foram preparados três diferentes elastômeros microcelulares de poliuretano (EMPU) baseados em 4,4'- diisocianato de difenilmetano (MDI), com diferentes concentrações de fase rígida (Formulações 1, 2 e 3, com 32, 35 e 42% de fase rígida, respectivamente). As amostras foram preparadas através do método de duas etapas, pelo sistema de pré-polímero. As amostras dos EMPU foram caracterizadas através de ensaios físico-mecânicos, químicos e morfológicos. Os resultados dos ensaios mecânicos mostraram que o aumento no percentual da fase rígida levou a um aumento na resistência à tração e na resistência ao rasgo. O alongamento na ruptura não apresentou variação significativa com a modificação do percentual da fase rígida. O ensaio de resistência química demonstrou que os EMPU formulados apresentaram baixos índices de inchamento para solventes industriais comumente utilizados. Entretanto, em acetona, um elevado índice de inchamento foi observado. As análises morfológicas indicaram que o aumento no percentual da fase rígida promoveu a formação de células menores distribuídas de forma mais homogênea no EMPU.

In this study, three different microcellular polyurethane elastomers (MPUE) based on 4,4'-diphenylmethane diisocyanate (MDI) with different rigid segment contents were prepared (Formulations 1, 2 and 3 with 32, 35 and 42% of rigid segment content, respectively). The MPUE were obtained through a two-step method using the prepolymer system. The samples were analyzed to determine their physical, mechanical, morphological and chemical properties. The results showed that a greater rigid segment content gave higher tensile, compressive and tear strength values. The deformation at break did not show significant changes with a variation in the rigid segment content. The MPUE had a low swelling index in common industrial solvents. However, in acetone a high swelling index was observed. The SEM micrographs indicated a large number of closed cells, and that a higher rigid segment content gave a better cell homogeneity of the samples.