Proizvodnja i karakterizacija poli(3-hidroksibutirata) iz oleinske kiseline s pomoću bakterije Ralstonia eutropha

The aim of this research is to investigate the influence of oleic acid concentration on the cell growth and the physical properties of the polymer formed by cultures of Ralstonia eutropha in mineral medium. Cells were cultivated in Erlenmeyer flasks with 300 mL of mineral medium, containing glucose and fructose as a carbon source (30 g/L) and ammonium sulphate (5.0 g/L) as a nitrogen source. Oleic acid was added as nutritional supplement in different concentrations (0, 0.3, 0.9, 1.5 and 3.0 g/L) and the cells were incubated at 30 °C and 150 rpm. The films prepared by casting were evaluated by X-ray diffraction, thermogravimetry and differential scanning calorimetry. These results indicate that the increase of oleic acid concentrations leads to a higher specific growth rate and cell productivity. The characterization of the films revealed that the increase of the concentration of oleic acid from 0 to 1.5 g/L has no influence on thermal behaviour and crystallinity degree. However, the thermal stability, melting temperature, glass transition temperatures and crystallinity degree decreased when 3.0 g/L of oleic acid were used.Svrha je ovoga istraživanja bila ispitati utjecaj koncentracije oleinske kiseline na rast stanica i fizikalna svojstva polimera koji proizvodi bakterija Ralstonia eutropha na mineralnoj podlozi. Stanice su uzgojene u Erlenmeyerovim tikvicama s 300 mL mineralne podloge, uz dodatak glukoze i fruktoze kao izvora ugljika (30 g/L) i amonijeva sulfata (5,0 g/L) kao izvora dušika. Kao dopunsko hranjivo dodana je oleinska kiselina u različitim koncentracijama (0; 0,3; 0,9; 1,5 i 3,0 g/L), nakon čega su stanice uzgojene na 30 °C pri 150 rpm. Lijevanjem dobiveni filmovi ispitani su difrakcijom x-zraka, termogravimetrijom i diferencijalnom skenirajućom kalorimetrijom. Rezultati su pokazali da je porast koncentracije oleinske kiseline uzrokovao povećanje specifične brzine rasta i broja stanica. Karakterizacijom filmova otkriveno je da koncentracija oleinske kiseline od 0 do 1,5 g/L nije utjecala na toplinska svojstva i stupanj kristalizacije. Međutim, toplinska stabilnost, talište, staklište i stupanj kristalizacije smanjili su se s povećanjem koncentracije oleinske kiseline iznad 3,0 g/L

Study of poly(lactic acid) films obtained by solution blow spinning reinforced with cellulose nanocrystals

Solution blow spinning is a technique to produce micro- and nano-scale fibers, forming films with high porosity and surface area. Chemical modifications or the incorporation of nanostructures in these fibers can improve the performance of these films for various applications, such as membranes, tissue engineering and sensors. Therefore, the aim of this work was to study poly(lactic acid) (PLA) films obtained by solution blow spinning reinforced with cellulose nanocrystals (CNC). First, different solvents were evaluated in order to determine the best processing conditions and the feasibility of using the solvent dimethyl carbonate (DMC) in the production of PLA films by solution blow spinning. Polymer concentration showed to be the most significant parameter affecting fiber diameter and DMC presented advantages over 1,1,1,3,3,3-hexafluoro-2-propanol (HFP) and chloroform due its less toxicity, and therefore, is an alternative solvent with an affordable price, using a more environmentally-friendly process. Subsequently, the CNCs were extracted from bleached eucalyptus kraft pulp by sulfuric acid hydrolysis, which were chemically modified with maleic anhydride (CNCMA). Then, composite films of PLA/CNC and PLA/CNCMA were obtained by solution blow spinning and the results indicated that the addition of nanocrystals did not significantly affected fiber diameters, although the fiber diameters tended to decrease with the increase of the nanocrystals concentration. The results also indicated that the nanocrystals may have increased the degree of PLA polymer chains orientation and that the composite films presented a more hydrophilic behavior when compared to the pure PLA film. It suggests that some of the nanocrystals may be on the surface of the fibers, indicating that these composite films are promising for filter and adsorbents membranes application.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A técnica de fiação por sopro em solução produz fibras em escala micro e nanométrica, formando filmes com elevada porosidade e área superficial. Modificações químicas ou a incorporação de nanoestruturas nestas fibras podem melhorar o desempenho destes filmes para diversas aplicações, como por exemplo, membranas, engenharia de tecidos e sensores. Portanto, o objetivo deste trabalho foi estudar filmes de poli(ácido lático) (PLA) obtidos por fiação por sopro em solução reforçados com nanocristais de celulose (CNC). Primeiramente, avaliou-se diferentes solventes a fim de determinar as melhores condições de processamento e a viabilidade de uso do solvente dimetilcarbonato (DMC) na obtenção de filmes de PLA por fiação por sopro em solução. A concentração de polímero mostrou ser o parâmetro mais significativo que afeta o diâmetro das fibras e que o DMC possui vantagens sobre o 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) e o clorofórmio por ser menos tóxico, sendo, portanto, um solvente alternativo com preço acessível, utilizando um processo ambientalmente mais correto. Em seguida, foram extraídos os CNC a partir da polpa branqueada de eucalipto via hidrólise com ácido sulfúrico, os quais foram modificados quimicamente com anidrido maleico (CNCMA). Então, foram obtidos filmes compósitos de PLA/CNC e PLA/CNCMA por fiação por sopro em solução e os resultados indicaram que a adição dos nanocristais não alterou significativamente o diâmetro das fibras, embora observou-se uma tendência de redução nos diâmetros com o aumento da concentração dos nanocristais. Os resultados também indicaram que os nanocristais podem ter aumentado o grau de orientação das cadeias poliméricas do PLA e que os filmes compósitos apresentaram caráter mais hidrofílico quando comparados ao filme de PLA puro. Isto sugere que parte dos nanocristais possam estar na superfície das fibras, indicando que estes filmes compósitos são promissores para aplicação em membranas filtrantes e adsorventes.CNPQ: 202445/2014-

Production and Characterization of Poly(3-Hydroxybutyrate) from Oleic Acid by Ralstonia eutropha

The aim of this research is to investigate the influence of oleic acid concentration on the cell growth and the physical properties of the polymer formed by cultures of Ralstonia eutropha in mineral medium. Cells were cultivated in Erlenmeyer flasks with 300 mL of mineral medium, containing glucose and fructose as a carbon source (30 g/L) and ammonium sulphate (5.0 g/L) as a nitrogen source. Oleic acid was added as nutritional supplement in different concentrations (0, 0.3, 0.9, 1.5 and 3.0 g/L) and the cells were incubated at 30 °C and 150 rpm. The films prepared by casting were evaluated by X-ray diffraction, thermogravimetry and differential scanning calorimetry. These results indicate that the increase of oleic acid concentrations leads to a higher specific growth rate and cell productivity. The characterization of the films revealed that the increase of the concentration of oleic acid from 0 to 1.5 g/L has no influence on thermal behaviour and crystallinity degree. However, the thermal stability, melting temperature, glass transition temperatures and crystallinity degree decreased when 3.0 g/L of oleic acid were used

Solution blow spun nanocomposites of poly (latic acid)/cellulose nanocrystals from eucalyptus kraft pulp.

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