Search

A new process for the production of nanocellulose from selected cellulose-containing natural materials has been developed. The liquefaction reaction, using glycols and mild acid catalysis (methane sulphonic acid), was applied to four model materials, namely cotton linters, spruce wood, eucalyptus wood and Chinese silver grass. The process contains only four steps, the milling, the glycolysis reaction, centrifugation and final rinsing with an organic solvent. The nanocrystalline cellulose recovery was between 56% and 75%. The crystallinity index was greater than that of the starting materials due to the liquefaction of lignin, hemicelluloses and amorphous cellulose. The final product was a stable, highly concentrated nanocrystalline cellulose suspension in the organic medium. The liquid residue, after the liquefaction of the cotton linters contained significant quantities of levulinic acid. Different sugars were identified in the liquid residues that were derived from cellulose and hemicelluloses during the liquefaction reaction. [ABSTRACT FROM AUTHOR]

Liquefied wood (LW) prepared in a microwave process was applied as a novel; inexpensive precursor feedstock for incorporation of (R)-3-hydroxyvalerate (3HV) into polyhydroxyalkanoate (PHA) biopolyesters in order to improve the biopolyester's material quality; Cupriavidus necator was applied as microbial production strain. For proof of concept, pre-experiments were carried out on a shake flask scale using different mixtures of glucose and LW as carbon source. The results indicate that LW definitely acts as a 3HV precursor, but, at the same time, displays toxic effects on C. necator at concentrations exceeding 10 g/L. Based on these findings, PHA biosynthesis under controlled conditions was performed using a fed-batch feeding regime on a bioreactor scale. As major outcome, a poly(3HB-co-0.8%-3HV) copolyester was obtained displaying a desired high molar mass of Mw = 5.39 × 105 g/mol at low molar-mass dispersity (ĐM of 1.53), a degree of crystallinity(Xc) of 62.1%, and melting temperature Tm (176.3 °C) slightly lower than values reported for poly([R]-3-hydroxybutyrate) (PHB) homopolyester produced by C. necator; thus, the produced biopolyester is expected to be more suitable for polymer processing purposes. [ABSTRACT FROM AUTHOR]

In this study, we modified melamine-formaldehyde (MF) resin adhesive with liquefied wood (LW) and determined the properties of MF–LW adhesive mixtures. Furthermore, we produced particleboards using prepared MF–LW mixtures and evaluated their mechanical and physical properties. Results showed that with increasing content of LW in the adhesive mixture gel time and peak temperature increased while reaction enthalpy decreased. With increasing substitution of MF resin adhesive with LW the thermal stability of adhesive mixture reduced, namely thermal degradation started at lower temperature and weight loss increased. Properties of particleboards improved with increasing amount of LW in the adhesive mixture up to 20% and then deteriorated. Nevertheless, the properties of particleboard with 30% LW in the adhesive mixture were comparable to the properties of particleboard without LW while they worsen at greater portion of LW. Consequently, MF resin adhesive with 30% LW substitution could be used to produce particleboards with suitable mechanical properties and reduced formaldehyde release content. [ABSTRACT FROM PUBLISHER]

ABSTRACT Depolymerized polyethylene terephthalate and liquefied wood polyesters can be used as a polyol for the production of polyurethane/polyisocyanurate foams. In this research, liquefied wood was synthesized by using a combination of diethylene glycol and glycerol and due to the possibility of using glycerol that is a by-product in biodiesel production, our goal was to use as much glycerol in the liquefaction reagent as possible. We determined the properties of the polyols, properties of produced foams, and explained their correlation. Greater amount of glycerol in the liquefaction reagent resulted in higher OH number, molecular weight, functionality, and viscosity of the polyol, as well as in longer cream time and tack free time in foam preparation. Glass transition temperature, density, and water absorption of the foam increased with increasing amount of glycerol in liquefied wood. Compressive stress increased up to 30% of the glycerol in the reagent and then reduced, while thermal conductivity was not affected. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41522. [ABSTRACT FROM AUTHOR]

After initial studies, further research work on the combustion properties of second generation biofuels, obtained through soivolysis in polyhydroxy alcohols is oriented towards different types of liquefied wood that exhibit several favorable properties. In this study, different types were obtained by altering the reactant ratios of the fuels. These were focused on increased wood content and elevated pH value that would increase the techno-economic attractiveness of the fuel. Three different types of fuels were tested in a laboratory scale gas turbine, and evaluated through CO, THC and NOx emissions measurements, while varying multiple operating parameters. To achieve sufficient atomization quality, the high viscosity of the fuels was reduced by preheating to 100 °C. To speed up the droplet evaporation process and additionally to resemble conditions present in commercially available systems, high temperatures of primary air were employed by the use of exhaust gas heat regenerator. CO and THC emissions were found to be highly dependent on wood content and turbine inlet temperature, whereas with partial neutralization of the fuel this dependency was less pronounced and only NOx concentrations were influenced by altered elemental composition of the fuel. Results indicate it is possible to maintain successful combustion in microturbines even with fuels that exhibit higher pH value and reduced reactivity and with fuels containing higher amounts of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the presented work was to replace phthalate based plasticizers with environmentally friendly materials to provide similar properties for poly(vinyl acetate) (PVAc) adhesives. Polyesters synthesized from the liquefied wood (PE-LW) and depolymerized polyethylene terephthalate (PE-PET) were used as renewable raw materials and evaluated as plasticizers used in PVAc dispersion adhesives for flooring applications. As a reference plasticizer, 1,2,3-triacetoxypropane was used. PVAc adhesives were evaluated with respect to solids content, viscosity, glass transition temperature (T g), tensile shear strength and binding strength. TGA analysis showed significant differences between the thermal stability of added polyesters and the commercial plasticizer. Samples prepared with PE-PET exhibit the best thermal stability even with an increase of 25% PE-PET. The addition of coalescing agents or plasticizers leads to a temporary softening of the PVAc polymer and a decrease in the glass transition temperature. The type and content of plasticizer have great influence on wood–wood binding strength, tensile strength and elongation. The requirements for the mechanical properties of adhesives were fulfilled by the compositions containing 8.8% (w/w) of PE-PET and 20% (w/w) of PE-LW. [Copyright &y& Elsevier]

Beech (Fagus Sylvatica) milled-wood lignin was used as a model substrate in a study of lignin-catalyzed liquefaction in the presence of p-toluene sulfonic acid monohydrate (PTSA) or sulphuric acid as the catalysts. The structural changes that lignin undergoes during the treatment were studied by NMR spectroscopy, FTIR, size-exclusion chromatography, and high-performance liquid chromatography. For the sulphuric acid-catalyzed liquefaction, it was shown that the greater hydronium ion concentration in the reaction mixture induced formation of more condensed structures compared to the ones obtained after PTSA-catalyzed liquefaction. In addition, lignin during the PTSA-catalyzed liquefaction suffered degradation and was functionalized by the ethylene glycol. Gradual introduction of the ethylene glycol moieties into the lignin structure formed a condensed lignin-based polymeric material with predominant aromatic hydroxyl groups. HPLC and NMR analysis of the liquefied lignin with low-molecular mass fraction confirmed the presence of lignin monomers and further conversion of initially identified products into the aliphatic, aromatic (syringyl- and guaiacyl-based) esters and acids. [ABSTRACT FROM PUBLISHER]

Cellulose was treated in ethylene glycol with p-toluene sulfonic acid monohydrate as a catalyst at different temperatures. At the highest treatment temperature (150 °C) liquefaction of wood pulp cellulose was achieved and was dependant on cellulose polymerization degree (DP). Furthermore, the rate of amorphous cellulose weight loss was found to increase with cellulose degree of polymerization, while the rate of crystalline cellulose weight loss was reciprocal to the size of the crystallites. The cellulose degradation was studied by monitoring of the molecular mass decrease by size-exclusion chromatography. It was revealed that microcrystalline cellulose degrades via a 'quantum mode' mechanism, while the degradation of Whatman filter paper no 1. and cotton linters proceeded randomly and were partly dependent on the starting polymerization degree, crystallinity, and treatment temperature. The kinetics of cellulose degradation in heterogeneous media was described by means of a one-stage model, characterised by the consumption of glycosidic bonds in amorphous and crystalline cellulose regions until the levelling-off degree of polymerization is reached. [ABSTRACT FROM AUTHOR]

Abstract: In our research, we have utilized high energy ultrasound for the liquefaction of different lignocellulosic materials, wood wastes in particular. We developed a highly efficient way of transforming this biomass waste into valuable chemicals. It was found, that the reaction yield in all experiments was high and that the reaction times were shortened up to nine times when using the ultrasound process with smaller residual particles and with no influence on the hydroxyl number of the final products. The use of the ultrasound process inhibits the formation of the large molecular structures during the liquefaction from the degradation products, by keeping the reactive segments apart and due to such a short reaction time being used. The short reaction time and subsequent low energy consumption for the liquefaction reaction leads to the creation of the new method for the transformation of the wood waste materials into valuable chemicals. [Copyright &y& Elsevier]

Abstract: A blend of spruce (Picea spp.) and fir (Abies spp.) sawdust was liquefied by an optimized technique in the presence of multifunctional alcohols and p-toluene sulfonic acid monohydrate as a catalyst. The lignin behaviour during wood liquefaction was studied at different reaction times. Samples prepared by the new separation procedure were characterized by quantitative 31P, 13C NMR and by size-exclusion chromatography. The final products showed increased molar masses indicating the condensation reactions between the lignin and the multifunctional alcohols. Aliphatic chains were found to be incorporated into the lignin network after liquefaction. The resulting polymer showed an increased content of aliphatic hydroxyl groups with respect to the starting material and a high degree of solubility in multifunctional alcohols. [ABSTRACT FROM AUTHOR]

Abstract: Different types of southern European hardwoods and softwoods were subjected to a liquefaction process with glycerol/diethylene glycol. The liquefied spruce wood was reacted in a condensation reaction in the hot press with different melamine–formaldehyde and melamine–urea–formaldehyde resin precursors and used as adhesives for wood particle boards. The mechanical properties of these particle boards and the determination of formaldehyde release, proved that addition of 50% of the liquefied wood to such resin precursors caused the product to meet the European standard quality demands for particle boards. Up to 40% reduction of the formaldehyde emission was achieved. The temperature of the press unit was lowered from 180°C to 160°C with no significant influence on the mechanical properties. On the basis of the presented results it was possible to conclude that liquefied wood can be used as substitute for synthetic resin precursors in adhesives that are used for the particle board production. [Copyright &y& Elsevier]

The article presents a study which performed liquefaction of Central-European softwoods meal using a mixture of diethylene glycol and glycerol and a minor addition of p-toluenesulfonic acid as a catalyst. Adipic acid and phthalic acid anhydrides were used as reagents in synthesizing three different polyesters. Fourier transform infrared (FTIR), gel permeation chromatography /size exclusion chromatography (GPC/SEC ), and viscosity measurements characterized the products.

Cellulose nanocrystals (CNCs) were surface modified by esterification in tetrahydrofuran (THF) at 25 °C using different catalysts and anhydrides bearing different alkyl side chain lengths. Unmodified and acetic anhydride (AcAnh)-modified CNCs were studied as potential nanofillers for linear low-density poly(ethylene) (LLDPE). Nanocomposites were prepared by melt processing. Determination of the size and size distribution of CNCs in the nanocomposites by SEM revealed an enhanced compatibility of the AcAnh-modified CNCs with the LLDPE matrix, since the average size of the aggregates of the modified CNCs (0.5–5 μm) was smaller compared to that of the unmodified CNCs (2–20 μm). Tensile test experiments revealed an increase in the nanocomposites’ stiffness and strain at break—by 20% and up to 90%, respectively—at the CNC concentration of 5 wt %, which is close to the critical percolation concentration. Since the CNC nanofiller simultaneously reduced LLDPE crystallinity, the reinforcement effect of CNCs was hampered. Therefore, the molding temperature was increased to 120 °C, and, in this way, the greatest increase of the Young’s modulus was achieved (by ~45%). Despite the enhanced compatibility of the AcAnh-modified CNCs with the LLDPE matrix, no additional effect on the mechanical properties of the nanocomposites was observed in comparison to the unmodified CNC. [ABSTRACT FROM AUTHOR]

Eco-friendly “green” nano composites were fabricated from potato starch and cellulose nanofibers from pineapple leaf. Nanocomposites of starch/cellulose nanofibers were prepared by solution mixing followed by casting. The investigation of the viscoelastic properties confirms starch macromolecular chain confinement around the nano scale cellulose surface, superior dispersion and very good interaction between thermoplastic starch and cellulose nanofibers. The degree of chain confinement was quantified. The chain confinement was associated with the immobilization of the starch macromolecular chains in the network formed by the nano-scale cellulose fibers as a result of hydrogen boding interactions. From the results, it was assumed that the starch glycerol system exhibits a heterogenous nature and cellulose nanofibers tend to move towards glycerol rich starch phase. Barrier properties also improved with the addition of nanofiller up to 3 wt.% but further addition depreciated properties due to possible fiber agglomeration. The kinetics of diffusion was investigated and typical kinetic parameters were determined and found that the nanocomposites follow pseudo fickian behaviour. The outcome of the work confirms that the prepared nanocomposites films can be used as a swap for packaging applications. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports foremost the results of a successful combustion of an innovative lignocellulosic biofuel in a gas turbine. The fuel was processed through liquefaction of lignocellulosic materials with polyhydroxy alcohols in an acid catalyzed reaction. The liquefaction process features: high efficiency, high liquid yields and inexpensive, easily available process equipment. For the purpose of this analysis the following were developed: an experimental gas turbine with internal combustion chamber, a preheated pressurized fuel supply system with swirl-air fuel injector and a heat exchanger to obtain high primary air temperatures. The paper gives results on the emissions of CO, THC, NOx and soot. For the purpose of benchmarking the turbine was also run on diesel fuel. The paper presents analyses of the underlying phenomena with which it aims to provide guidelines for improvements in the fuel processing and in the experimental equipment. It has been shown that direct utilization of this innovative lignocellulosic biofuel gives promising results. Although the CO and THC emissions are higher compared to the benchmark diesel results it has been shown that both emissions decrease with increased turbine inlet temperature and with the increased fuel preheat temperature, due to a very high viscosity of the fuel. It is additionally shown that NOx emissions are low and comparable to those of the diesel fuel, whereas soot emissions are very low for both fuels. [Copyright &y& Elsevier]

In this research work, we propose a synergistic effect of a green crosslinker and cellulose nanomaterial on the crystallinity, viscoelastic, and thermal properties of starch nanocomposites. A disaccharide derivative was used as a bio crosslinker and nanofiber from pineapple leaf as a reinforcing phase for starch. Sucrose was oxidised using periodate, that can selectively oxidise the vicinal hydroxyl group of sucrose and form tetra aldehyde derivative. Crystallinity of films after crosslinking decreased with successive addition of crosslinker. The melting temperature of films increased because of formation of more dense structure after crosslinking. Morphological investigations were analysed by atomic force microscopy. Polymer chain confinement and mechanics were quantified. The crosslink densities of the films were calculated using two models, phantom model and affine model, using storage modulus data. By using very low amount of crosslinker and nanoreinforcement, the properties of thermoplastic starch were significantly improved. Unlabelled Image [ABSTRACT FROM AUTHOR]