Volume 7 Issue 1

The effects on sugar yields of acid concentration, temperature, and time in the first (decrystallization) stage of a two-stage concentrated sulfuric acid hydrolysis of softwood (Scots pine) and hardwood (aspen) were investigated. The study focused on the multi-variable effects of the decrystallization stage and applied a statistical modeling with Central Composite Face (CCF) design of experiment to systematically study and simulate the effect of decrystallization reaction conditions on hydrolysis products and degradation products. The models were statistically significant and showed that for both aspen and pine, the reaction temperature and acid concentration were the most influential variables on monosaccharides and total sugar yields compared to the reaction time. The interaction between temperature and acid concentration was the most important for both species. The sugar degradation products were much influenced by the decrystallization temperature on both aspen and pine. The models were validated by a test-set and showed a good agreement between the experimental and predicted values. The optimum predicted total sugar yields were 56 g / 100 g d.w for aspen (74% theoretical) and 64 g / 100 g d.w for pine (91% theoretical).

Paulownia Tomentosa was pretreated by steam explosion. The cellulase complex NS 50013 and the β-glucosidase NS 50010 of Novozymes AS were used for the enzymatic conversion of cellulose to glucose. The kinetics of enzyme conversion was studied using the exponential kinetic equation valid for processes taking place at uniformly inhomogeneous surfaces. The kinetic coefficient of inhomogeneity accounts for the energy and entropy inhomogeneity of the system and depends on the temperature. It was established that both the activation energy and the pre-exponential factor increase simultaneously with increasing of conversion degree. A compensation effect between pre-exponential factor and activation energy was observed. The energetic hindrances established cannot be completely compensated by the positive effect of the pre-exponential factor increase. Hence, the activation energy has a determining influence on how quickly the rate of hydrolysis decreases.

In this study three different ways of applying ultrasound for the production of nanocellulose from native cellulose were explored. In the first option bleached hardwood kraft pulp was oxidized with the ultrasound (US) assisted TEMPO/NaBr/NaOCl-system (US-TEMPO-system) followed by mechanical separation of nanocellulose. The pulp oxidized by the US-TEMPO-system had higher carboxyls content and ca. 10% increase in nanocellulose yield when compared to the TEMPO-system without sono catalysis. In the second option ultrasound pretreated pulp was oxidized using the TEMPO-system. Although there was no gain in carboxyls content in this process versus the oxidation with TEMPO-system without ultrasound treatment, a higher degree of fibrillation was obtained after ultrasound treatment. In the third case the TEMPO oxidized pulp was subjected to mechanical and ultrasound treatments for nanocellulose production. Under similar treatment time the subsequent ultrasound treatment achieved higher nanocellulose yield than the subsequent mechanical treatment. However, in comparison, the ultrasound treated nanocellulose had lower Rheometer Stresstech viscosity. Furthermore, it was observed that cellulose nanofibrils produced by ultrasound treatment were slightly thinner compared to those produced using the mechanical method.

The objective of this study was to determine the effects of some boron compounds, which have fire retardant properties, as well as melamine-urea-formaldehyde (MUF) resins having different melamine contents (10%, 15%, and 20%) on some physical and mechanical properties of medium density fiberboard (MDF) panels. It was found that the water absorption (WA) and thickness swelling (TS) of MDF panels increased depending on types and concentrations of boron compounds. However, the WA and TS values of MDF panels decreased with increasing melamine content in MUF resins. It was also found that the modulus of rupture (MOR) and internal bond strength (IB) of MDF panels showed different trends depending on the experimental parameters. Boron compounds showed some negative effects on the MOR and IB values. However, these effects decreased with increasing melamine content in MUF resins. The best results were obtained in MDF panels manufactured with an MUF resin having 20% melamine content. Consequently, increasing melamine content in MUF resins showed positive effects on some properties of MDF panels.

A tung oil (TO) based monomer for rigid thermosetting polymer was synthesized, characterized, and copolymerized with styrene in this study. Tung oil was alcoholyzed with pentaerythritol (PER) to get tung oil pentaerythritol alcoholysis products (TOPER), and the optimized conditions were explored according to the yields of TOPER analyzed by gas chromatography-mass spectrometry (GC-MS). The resulting alcoholysis products were maleinated to form tung oil maleate half ester (TOPERMA), and the reaction conditions were determined by monitoring the reaction extents of TOPER and maleic anhydride (MA) with 1HNMR spectroscopy. The TO alcoholysis and maleinization reaction products were characterized by IR, 1HNMR, and electrospray ionization-mass spectrometry (ESI-MS) techniques. At last, the TOPERMA mixture was cured with styrene (St), and the initiator tert-butyl peroxy benzoate (TPB). Differential scanning calorimetry (DSC) was employed to characterize the curing process. Mechanical properties of the cured TOPERMA/St resin further confirmed the best procedure for the maleinization reaction. The loading of TO reached about 30% weight of the resulting thermosetting polymer. This promising material from renewable resources can be a potential substitution for petroleum products when used as sheet molding compounds.

Nowadays, the discovery of lignocellulolytic microorganisms that are better adapted to operational conditions while exhibiting the strong degrading activities is highly desired for successful lignocellulose biotransformation processes. In this study, microorganisms were isolated from lignocellulose-rich composting materials by selective methods. A screening of isolates known to have lignocellulolytic abilities was performed using several tests. Seven microorganisms showed ligninolytic potential and were subjected for further analysis according to their degrading activity. The fungus Pseudallescheriaangusta MF4 demonstrated high decolorization rates for three aromatic dyes: Poly R-478, Poly S-119, and Remazol Brilliant Blue R. In addition, the fungus showed a high production rate of ligninolytic enzymes in the presence of inducers. This fungus achieved the highest values of growth after 21 days of incubation on sawdust without any additional nutrients. Owing to its proven ligninolytic activity and capability of growing on a lignocellulosic substrate, the application of this isolate could be of interest in different biotechnological applications, particularly in biological treatment of wood fibres in order to improve the production of wood-based composites.

The potential use of kapok fiber for pulping and papermaking has been investigated. The kapok fibers were cooked using the optimal dosage of sodium hydroxide determined from the experiments. Then, the pulp was refined with two passes using a disc refiner and mixed with commercial hardwood pulp and/or softwood pulp at different blend ratios to make papers. It was found that addition of the kapok pulp to the mixed pulps improved the tensile and burst strengths of the sheets but decreased the tear resistance and elongation. Water repellency of the sheets prepared from the kapok pulp mixed with the commercial pulps was also improved. These results indicate that kapok fiber can be a quality pulp source for papermaking, especially for packaging paper requiring strength and water repellency.

This research provides an optimal design of structural parameters for ring-die granulators used in the cool briquetting process. Experimental research on the briquetting rate of pellets was carried out for three kinds of crop straws with different granularities, moisture ratios, and length-diameter ratios of the die hole. Results showed that: when the swoop angle β was 45o and the diameter ratio of roller to die was equal to 0.585, the equipment would have higher productivity and lower die-roller contact strength, yielding a good comprehensive briquetting effect; when the granularity was 4mm, the moisture ratio was 16% and the length-diameter ratio was 5.2, the equipment would ensure a higher briquetting rate of pellets and the lowest power consumption per ton of material, yielding the best briquetting effect. This provides references for structural design and process parameters selection of ring-die granulators.

This study examines the dimensional stability of fast-growing poplar clones wood after treatment by impregnation with methyl methacrylate (MMA). Six hybrid poplar clones from one plantation in Quebec were sampled. The effects of hardening with MMA on density as well as longitudinal, radial, tangential, and volumetric swelling properties (S), water uptake capacity (D), anti-swelling efficiency (ASE), and water repellent efficiency (WRE) after soaking were investigated. Hardening treatment increased the density of all poplar woods by 1.2 to 1.6 and decreased the inner water migration rate during soaking. S and D values of hardened woods were significantly lower than those of controls, depending on the clone type. ASE and WRE values suggested that incorporating MMA effectively improved the dimensional stability of poplar wood at the early soaking stage, but was less effective in the long term.

The organization of the major polymers in the wood fiber has a large impact on the properties of the structure. Numerous studies have been devoted to the cellulose microfibril arrangement, providing the longitudinal strength of the fiber, while less is known regarding the structural organization of other components, such as hemicelluloses and lignin. For the hemicelluloses, as being part of the cellulose aggregation process, indications of a strong coupling to the cellulose structure have been shown. For lignin, being laid down in a later stage, no clear picture has emerged. Here the orientation of lignin vis-à-vis the cellulose orientation was examined for a number of different fiber structures. It was shown that the lignin in the middle lamella region seems to be non-oriented, thus more resembling an isotropic material, while the lignin in the secondary wall is to some extent oriented. The orientation of this lignin is less pronounced than the orientation of cellulose but has a preferential alignment in the direction of the fiber axis. The reason for this alignment could be related to structural restrictions of this lignin, deposited in the spaces remaining after the initial forming of the structured cellulose/hemicellulose fibrillar structure.