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In this study, the target was the generation of fermentable monosaccharides from hardwoods that can be converted into value-added chemicals, such as polyhydroxybutyrates (PHB). Poplar flour was subjected to a hot-water pretreatment. The pretreatment conditions were optimized using a response surface methodology (RSM) on a 2 3 full central composites design by varying temperature, reaction time and solid loading. The optimal pretreatment condition for producing sugars was 200 °C, 22 min and 20% solid loading. After pretreatment the solid residue was treated with a commercial cellulase/xylanase preparation and released sugars quantified. The total sugars yield was applied as response variable to the RSM. A maximum yield of 96% sugars was obtained. Potential fermentation inhibitors were also detected at low concentrations (acetic acid, furfural, hydroxymethylfurfural). A preliminary trial using wood hydrolysates in a fed-batch bioreactor using a mixed microbial consortia afforded PHB (14% on biomass basis) and maximum PHB productivity of 0.18 g/L/h. [ABSTRACT FROM AUTHOR]

Abstract: The preparation of hyperbranched polymers from a unique combination of commercially available A2, B3 and CB1 3-type monomers is presented. Direct melt condensation of aliphatic dicarboxylic acid (A2) to compounds having trihydroxy groups ((B3), triethanolamine) and trihydroxy-monoamino groups ((CB1 3), tris(hydroxymethyl)aminomethane) led to a series of hyperbranched polyesters with amine cores and amide linkages. Because of the monomers availability and simplicity of the synthetic process, hyperbranched poly(ester-amine-amide) (HBPEAA) materials can be readily scaled up. This approach was used to synthesize series of prepolymers with varying degree of branching (DB) and distance between branching points. Taking the advantage of reactivity differences of COOH with the NH2 and OH groups, the hyperbranched polymer with different arrangement of amide linkage along the network was synthesized. The influence of reaction conditions such as monomer compositions, temperature and mode of mixing on the polymerization was examined. The DB of the HBPEAA (0.46–0.63) was dependant on the synthetic route. The HBPEAA exhibited moderate molecular weights as determined by NMR and ESI-MS. Thermogravimetric analysis revealed that the prepolymers exhibit reasonable thermal stability. The synthesized prepolymer was successfully utilized to copolymerize with 40% lignin to form toughened elastomeric materials with tensile strength of 12 MPa, Young''s modulus of 33 MPa and 149% elongation. [Copyright &y& Elsevier]

Abstract: Combined characteristics of hydrogen bonded/cross-linked polymer networks based on lignin motifs have been developed. This new type of polymeric material was prepared from an industrial lignin and a highly branched poly(ester-amine) (HBPEA) obtained by melt polycondensation of 1,1,1-triethanolamine (TEA) and adipic acid (AA). The lignin-HBPEA polymers were shown to be insoluble in common organic solvents and were characterized by FTIR and NMR spectroscopies. Thermo-mechanical measurements showed that melt mixing HBPEA with 40% lignin results in a flexible and tough material (T g; 7.7 °C and E′ 3.5 GPa). The hydrogen bonding recognition was based on various hydroxyl groups in lignin and aliphatic ester groups from HBPEA. The extent of interactions could be controlled by varying the amount of lignin added. These networks were thermally reversible and have highly tunable mechanical properties that were controlled by the extent of interactions. High level of mechanical properties could be achieved through the addition of lignin-poly(ester-amine) covalent cross-links. This study shows that the poly(ester-amine) structure plays an important role in the thermo-mechanical properties. By varying the spacer length between lignin and tertiary amine unit, materials with various thermo-mechanical properties were also obtained from the same parent polymer backbone. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrate (PHB) is a bioplastic biosynthesized by microorganisms as an intracellular granule. In this study, PHB was produced by a mixed microbial culture fed crude glycerol in a sequencing batch bioreactor. Bioreactor operations were monitored by near infrared (NIR) spectroscopy (908–1708 nm) with a direct insertion probe to develop a model for predicting microbial PHB concentration. Multivariate statistical methods, principal component analysis (PCA) and partial least squares (PLS), were applied for modeling of the NIR spectral data. The results showed that NIR spectra can (i) be used to predict PHB content in-situ, with a calibration model and prediction model exhibiting a good fit (R 2 = 0.88 and R 2 = 0.89, respectively) and (ii) also be used to monitor substrate, glycerol, concentration. [ABSTRACT FROM AUTHOR]

The formation of liquid intermediates and the distribution of products were studied under slow and fast pyrolysis conditions. Results indicate that monomers are formed from lignin oligomeric products during secondary reactions, rather than directly from the native lignin. Lignin from Douglas-fir (Pseudotsuga menziesii) wood was extracted using the milled wood enzyme lignin isolation method. Slow pyrolysis using a microscope with hot-stage captured the liquid formation (>150 °C), shrinking, swelling (foaming), and evaporation behavior of lignin intermediates. The activation energy (E a) for 5–80% conversions was 213 kJ mol−1, and the pre-exponential factor (log A) was 24.34. Fast pyrolysis tests in a wire mesh reactor were conducted (300–650 °C). The formation of the liquid intermediate was visualized with a fast speed camera (250 Hz), showing the existence of three well defined steps: formation of lignin liquid intermediates, foaming and liquid intermediate swelling, and evaporation and droplet shrinking. GC/MS and UV-Fluorescence of the mesh reactor condensate revealed lignin oligomer formation but no mono-phenols were seen. An increase in pyrolytic lignin yield was observed as temperature increased. The molar mass determined by ESI-MS was not affected by pyrolysis temperature. SEM of the char showed a smooth surface with holes, evidence of a liquid intermediate with foaming; bursting from these foams could be responsible for the removal of lignin oligomers. Py-GC/MS studies showed the highest yield of guaiacol compounds at 450–550 °C. [ABSTRACT FROM AUTHOR]