Avaliação das propriedades físico-químicas de sistemas a base de carboximetilcelulose e poli (N-isopropilacrilamida) em soluções aquosas para aplicação na indústria do petróleo

Sustainable development is a major challenge in the oil industry and has aroused growing interest in research to obtain materials from renewable sources. Carboxymethylcellulose (CMC) is a polysaccharide derived from cellulose and becomes attractive because it is water-soluble, renewable, biodegradable and inexpensive, as well as may be chemically modified to gain new properties. Among the derivatives of carboxymethylcellulose, systems have been developed to induce stimuli-responsive properties and extend the applicability of multiple-responsive materials. Although these new materials have been the subject of study, understanding of their physicochemical properties, such as viscosity, solubility and particle size as a function of pH and temperature, is still very limited. This study describes systems of physical blends and copolymers based on carboxymethylcellulose and poly (N-isopropylacrylamide) (PNIPAM), with different feed percentage compositions of the reaction (25CMC, 50CMC e 75CMC), in aqueous solution. The chemical structure of the polymers was investigated by infrared and CHN elementary analysis. The physical blends were analyzed by rheology and the copolymers by UV-visible spectroscopy, small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and zeta potential. CMC and copolymer were assessed as scale inhibitors of calcium carbonate (CaCO3) using dynamic tube blocking tests and chemical compatibility tests, as well as scanning electron microscopy (SEM). Thermothickening behavior was observed for the 50 % CMC_50 % PNIPAM and 25 % CMC_75 % PNIPAM physical blends in aqueous solution at concentrations of 6 and 2 g/L, respectively, depending on polymer concentration and composition. For the copolymers, the increase in temperature and amount of PNIPAM favored polymer-polymer interactions through hydrophobic groups, resulting in increased turbidity of polymer solutions. Particle size decreased with the rise in copolymer PNIPAM content as a function of pH (3-12), at 25 °C. Larger amounts of CMC result in a stronger effect of pH on particle size, indicating pH-responsive behavior. Thus, 25CMC was not affected by the change in pH, exhibiting similar behavior to PNIPAM. In addition, the presence of acidic or basic additives influenced particle size, which was smaller in the presence of the additives than in distilled water. The results of zeta potential also showed greater variation for polymers in distilled water than in the presence of acids and bases. The lower critical solution temperature (LCST) of PNIPAM determined by DLS corroborated the value obtained by UV-visible spectroscopy. SAXS data for PNIPAM and 50CMC indicated phase transition when the temperature increased from 32 to 34 °C. A reduction in or absence of electrostatic properties was observed as a function of increased PNIPAM in copolymer composition. Assessment of samples as scale inhibitors showed that CMC performed better than the copolymers. This was attributed to the higher charge density present in CMC. The SEM micrographs confirmed morphological changes in the CaCO3 crystals, demonstrating the scale inhibiting potential of these polymers

Thermal and pasting properties of cassava starch-dehydrated orange pulp blends

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Vegetal polymer in repair of defects of the orbital floor: an experimental study in rabbits

Background: An experimental study was done to assess the ability of the vegetal polymer miniplates and screws to repair defects of the orbital floor.Methods: An artificial standard-sized defect was created in the bony floor of right orbit of 45 albino rabbits. The animals were divided into three experimental groups: control group (G1) involving animals with orbital floor defect and no treatment; titanium group (G2) containing animals with orbital floor defect repaired by titanium miniplates and screws; vegetal polymer group (G3) composed of animals with similar orbital floor defects repaired by vegetal polymer miniplates and screws. Throughout the course of the experiment, the animals were clinically evaluated. At 15, 30 and 60 days after surgery, the animals were killed. They were X-rayed immediately after the floor defect and at the moment of sacrifice. Histological and morphometric evaluation of inflammatory reaction and bone healing was done. Data were statistically evaluated.Results: No implants were extruded. Bone consolidation was similar in G2 and G3 and better than in G1 group animals. Inflammatory reaction was most pronounced in animals of G3 15 days after surgery, and it subsided over time.Conclusion: Vegetal polymer miniplates and screws induces small inflammatory reaction and had the ability to stimulate bone growth with good integration in the orbital floor defect allowing to consider the vegetal polymer adequate option to treat orbital floor defects. Future studies involving long-term follow-up and biomechanical tests to evaluate material resistance to traction are needed.

Histomorphometric evaluation of human sinus floor augmentation healing responses to placement of calcium phosphate or Ricinus communis polymer associated with autogenous bone

Background: Prosthetic rehabilitation of the posterior maxilla with dental implants is often difficult because of proximity to the maxillary sinus and insufficient bone height. Maxillary sinus floor augmentation procedures aim to obtain enough bone with an association between biomaterials and autogenous bone.Purpose: the purpose of this study was to evaluate histomorphometrically two grafting materials (calcium phosphate and Ricinus communis polymer) used in maxillary sinus floor augmentation associated with autogenous bone.Materials and Methods: Biopsies were taken from 10 consecutive subjects (mean age 45 years) 10 months after maxillary sinus floor augmentation. The sinus lift was performed with a mixture of autogenous bone and R. communis polymer or calcium phosphate in a 1:2 proportion. Routine histologic processing and staining with hernatoxylin and eosin were performed.Results: the histomorphometric analysis indicated satisfactory regenerative results in both groups for a mean of bone tissue in the grafted area (44.24 +/- 13.79% for the calcium phosphate group and 38.77 +/- 12.85% for the polymer group). Histologic evaluation revealed the presence of an inflammatory infiltrate of mononuclear prevalence that, on average, was nonsignificant. The histologic sections depicted mature bone with compact and cancellous areas in both groups.Conclusion: the results indicated that both graft materials associated with the autogenous bone were biocompatible, although both were still present after 10 months.

Effect of an acrylic resin combined with an antimicrobial polymer on biofilm formation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genotoxicity assessment of water soluble fractions of biodiesel and its diesel blends using the Salmonella assay and the in vitro MicroFlow (R) kit (Litron) assay

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxicity of water-soluble fraction from biodiesel and its diesel blends to human cell lines

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphological Changes in Poly(Caprolactone)/Poly(Vinyl Chloride) Blends Caused by Biodegradation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and morphological changes in Poly(caprolactone)/poly(vinyl chloride) blends caused by UV irradiation

Films made from a blend of poly(epsilon-caprolactone) and poly(vinyl chloride) (PCL/PVC) retained high crystallinity in a segregated PCL phase. Structural and morphological changes produced when the films were exposed to high potency ultraviolet (UV) irradiation for 10 h were measured by UV-Vis spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). They were different to those observed with homopolymer PCL and PVC films treated under the same conditions. The FTIR spectra of the PCL/PVC blend suggest that blending decreased the susceptibility of the PCL to crystallize when irradiated. Similarly, although scanning electron micrographs of PCL showed evidence of growth of crystalline domains, particularly after UV irradiation, the images of PCL/PVC were fairly featureless. It is apparent that the degradation behavior is strongly influenced by the interaction of the two polymers in the amorphous phase.

Aerobic biodegradation of butanol and gasoline blends

This work aimed to assess the aerobic biodegradation of butanol/gasoline, blends (5; 10; 15 and 20% v/v), being the latter compared to the ethanol/gasoline blend (20% v/v). Two experimental techniques were employed, namely the respirometric method and the redox indicator DCPIP test. in the former, experiments simulating the contamination of natural environments (addition of 50 mL of fuel kg(-1) of soil from a non-contaminated site and 20 mL of fuel L(-1) of water from a river) were carried out in biometer flasks (250 mL), used to measure the microbial CO(2) production. The DCPIP test assessed the capability of four inocula to biodegrade the blends of 20%. The addition of butanol at different concentrations enhanced the biodegradation of gasoline in soil. However, no practical gains were observed for concentrations of butanol above 10%. Ethanol showed to have a much faster biodegradation rate than butanol, particularly in water, and the following order of biodegradability was found: ethanol > butanol > gasoline. The addition of the alcohols to the gasoline resulted in positive synergic effects on the biodegradation of the fuels in soil and water matrices. Furthermore, results suggest that, in soil, butanol better enhanced the biodegradation of gasoline than ethanol. (C) 2009 Elsevier Ltd. All rights reserved

Biodegradation of biodiesel/diesel blends by Candida viswanathii

This work is aimed to assess the aerobic biodegradation of biodiesel/diesel blends (0, 2, 5, 20 and 100%, v/v) by Candida viswanathii. The biodegradation potential of the inoculum was assessed with the redox indicator 2,6-dichlorophenol indophenol (DCPIP) test and with respirometric experiment in biometer flasks (250 mL) used to measure the microbial CO(2) production. In the latter, the inoculum was added to a contaminated soil with the blends (addition of 50 mL of fuel/Kg of soil from a non-contaminated site). C. viswanathii was able to increase significantly (approximately 50% in terms of CO(2) production) the biodegradation in soil of biodiesel/diesel blends and neat biodiesel since it preferable biodegrades biodiesel. Without inoculum the biodegradation of diesel oil was higher than biodiesel and blends (47.3, 51.1, 5.7 and 22.1% in terms of CO(2) production by B2, B5, B20 and B100, respectively) presumably due to the presence of the antioxidant terc-butyl-hydroquinone (TBHQ) in the biodiesel.

Aerobic biodegradation of butanol and diesel oil blends

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Application of abrupt cut-off models in the analysis of the capacitance spectra of conjugated polymer devices

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Polymer induced condensation of DNA supercoils

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electroluminescence and electric current response spectroscopy applied to the characterization of polymer light-emitting electrochemical cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)