Volume 6 Issue 1

In this work tannin was isolated from the outer bark of the eucalyptus tree, then treated with Ba(OH)2 to synthesize barium tannate (Ba-tan). The derivative was evaluated as a thermal stabilizer for polyvinyl chloride (PVC). PVC was mixed with Ba-tan thermally at four percentages (0.5, 1.0, 2.0, and 2.5)% w/w. The samples were pressed thermally to films having thickness ranging between 0.25 and 0.30 mm. The effect of Ba-tan was studied by monitoring the weight of samples under iso-thermal conditions at 250 oC. Thermal stability of PVC increased with increasing Ba-tan percent. Samples weight curves also indicated that the additive had been suitably active to increase the resistance of PVC against thermal degradation, where the degradation rates decreased from about 0.21 % wt/min. at 0.5% of Ba-tan on PVC to reach to 0.05% wt/min. for the 2.5% treated sample. The ability of Ba-tan to react with and remove HCl from the system of polymer during thermal conditioning of samples and during the measurement led to this effect. Therefore the present results demonstrate the performance of this derivative as a thermal stabilizer.

Three switchgrass cultivars (‘Performer’, ‘BoMaster’, and ‘Colony’ switchgrass) were delignified using NaOH at varying concentrations and residence times at 121 oC for improved sugar production in enzymatic hydrolysis. Because of its greater carbohydrate/lignin ratio and the more substantial lignin reduction upon alkaline attack, ‘Performer’ switchgrass gave greater sugar productions under all the pretreatment conditions investigated. Maximum sugar production from ‘Performer’ was 425 mg/g raw biomass, which was achieved at 1% NaOH and 0.5 h. Sugar production increased with the improvement of delignification until the lignin reduction reached 30%. The more severe pretreatment conditions, which led to greater lignin reductions, did not favor the increase of sugar production because of greater solid losses. Linear models were proven effective in correlating a modified severity parameter log(Mo) to lignin reduction and sugar production of ‘Performer’ switchgrass.

The adsorption of xylan on pulp fibers improves the strength properties of paper. However, the optical properties are decreased significantly. The objective of our research was to bleach hardwood kraft pulp with adsorbed birch xylan by hydrogen peroxide and study the effect of bleaching parameters on paper properties. The bleaching parameters studied included bleaching temperature, time, initial pH as well as MgSO4 dosage. The optical properties (whiteness, brightness, opacity) and physical properties (tensile index, tearing index, bulk) of handsheets made from the pulp bleached with different process variables were measured. The results showed that better optical properties were obtained with higher bleaching temperature, longer bleaching time, and more MgSO4 dosage. Bleaching from an initial pH of 11 provided the highest brightness value. On the other hand, strength properties were improved with decreasing of the bleaching temperature, and increasing the initial pH and MgSO4 dosage. The relationship between strength properties and bleaching time varied depending on bleaching temperature. According to the results, both good mechanical properties and optical properties could be achieved when the operating parameters were controlled properly. Therefore hydrogen peroxide bleaching was proved to be a suitable method for bleaching hardwood kraft pulp with adsorption of birch xylan.

In this study the tropical light hardwood species jelutong (Dyera costulata), terbulan(Endospermum diadenum), batai (Paraserianthes moluccana), rubberwood (Hevea brasiliensis), and pulai (Alstonia pneumatophora) were treated with benzene diazonium salt to improve their dynamic Young’s modulus (Ed), and thermal stability. Benzine diazonium salt reacted with cellulose in wood and produced 2,6-diazocellulose by a coupling reaction, as confirmed by Fourier transform infrared (FTIR) spectroscopy. Values of Ed were calculated from the free-free flexural vibration method and found to increase on treatment. The morphological properties were studied by FTIR and scanning electron microscopy (SEM) and found to be changed. Thermal properties of treated wood samples were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The treated wood samples exhibited an increased thermal stability relative to the untreated wood samples; this increase may be related to the formation of 2, 6-diazo cellulose compound.

This study was centered on finding a locally sourced alternative to imported long-fibre pulp for Nigerian pulp and paper mills. Fibre characteristics, chemical composition, and paper properties of pulp handsheets at different levels of kappa number and freeness in the range of 10 oSR and 62 oSR were evaluated using air-dried bast fibre obtained from decorticated kenaf plants grown in southern guinea savanna near Jebba, Nigeria. Kenaf bast fibre compared well with softwood, with an average fibre length of 2.90 mm, a flexibility ratio of 57%, and a Runkel ratio of 0.76. Ash, lignin, and pentosan contents were 0.6%, 12.5%, and 10.6%, respectively, while the cellulose content was 55.5%. Under alkali charge of 15.0 and, sulphidity of 17.5 with constant temperature, cooking time, and liquor-to-fibre ratio of 4.5:1, the screen yield was between 48.8 to 52.8 % with kappa number 12.04 to 20.5. Unbleached pulpsheets at kappa number between 15 and18.5 and pulp freeness 55 oSR and bleached pulp freeness between 148 and 336 mLs had better quality paper in terms of overall pulpsheet strength properties.

Extrusion can be a viable continuous biomass pretreatment that industry can adopt readily due to its uniqueness (including pretreatment time less than 90 s) over other pretreatment methods. The current study was undertaken to evaluate the combined effect of alkali soaking and extrusion of big bluestem to improve the sugar recovery to nearly quantitative. In order to evaluate the combined effect of alkali soaking and extrusion on the performance of enzymatic saccharification, big bluestem (2-10 mm) was soaked in different alkali concentrations (0.5-2.5 % w/v NaOH) for 30 min at room temperature and then extruded using a lab scale single screw extruder at various barrel temperatures (45-225°C) and screw speeds (20-200 rpm). Statistical analyses confirmed that all the independent variables considered had a significant effect on sugar recovery. A proposed quadratic model to predict sugar recovery had high F and R2 values with a low p value, and adequately represented the relationship among the independent variables on sugar recovery. The optimum pretreatment condition found was the following: 90°C barrel temperature, 155 rpm screw speed, 2.0% alkali concentration, and 4 mm particle size resulted the maximum glucose, xylose, and combined sugar recovery of 90.1, 91.5, and 89.9%, respectively.

The usage of non-wood pulps in furnishes for the production of various paper grades is a real alternative for the substitution of wood pulp in papermaking. In terms of the papermaking process, the main limiting factor for non-wood pulp utilization is poor dewatering. This problem can be partially solved by means of retention aids, and the modern microparticle-based retention aids are very promising for this application. In this study the main aim was to characterize how the microparticle retention systems affect the retention, dewatering, and formation of a non-wood pulp furnish and how these effects and mechanisms differ when compared to normal wood pulp. The performance of several commercially available retention aids was studied by making dynamic sheet forming tests for reference and an organosolv wheat straw furnish. The emphasis in the experiments was on drainage enhancement. The maximum drainage gain obtained with the bentonite-CPAM retention aid system was about 5%. Despite the improved drainage, dewatering of the reference furnish was better than for the non-wood containing furnish.

The assessment of wood biomass density through multivariate modeling of mid-infrared spectra can be useful for interpreting the relationship between feedstock density and functional groups. This study looked at predicting feedstock density from mid-infrared spectra and interpreting the multivariate models. The wood samples possessed a random cell wall orientation, which would be typical of wood chips in a feedstock process. Principal component regression and multiple linear regression models were compared both before and after conversion of the raw spectra into the 1st derivative. A principal component regression model from 1st derivative spectra exhibited the best calibration statistics, while a multiple linear regression model from the 1st derivative spectra yielded nearly similar performance. Earlywood and latewood based spectra exhibited significant differences in carbohydrate-associated bands (1000 and 1060 cm-1). Only statistically significant principal component terms (alpha less than 0.05) were chosen for regression; likewise, band assignments only originated from statistically significant principal components. Cellulose, lignin, and hemicelllose associated bands were found to be important in the prediction of wood density.

Hardwood soda-AQ pulps are believed to be rich in benzyl sugar ethers (BSE) that can be partially cleaved by aqueous acidic treatments. The aim of this investigation was to evaluate the effect of acidolysis on final bleached brightness for kraft and soda-AQ (SAQ) hardwood pulps. The increase in final brightness due to acidolysis at 110 °C was twice as high for a eucalyptus SAQ pulp as compared to the kraft pulp. An oxygen delignified maple C-SAQ pulp (carbonate pre-treated SAQ) was acidolyzed at 120 °C and pH 2.6 for 30 min. When 1.60% ClO2 + 0.25% H2O2 on pulp was used in DEPD final bleaching of the control sample a brightness of 91.5% was achieved. When only 1.00% ClO2 + 0.25% H2O2 on pulp was used for the acidolyzed sample a brightness of 92.0% was attained. Analyses of the maple pulp after the acidolysis showed no major change in lignin content, brightness, or pulp yield. The minor changes suggest that a facile reaction such as benzyl ether cleavage was responsible for the improved bleachability. Preliminary research involving a lignin model compound and commercial birch xylan showed that lignin-carbohydrate condensation products were generated under SAQ cooking conditions. Furthermore, a fraction of these lignin-carbohydrate moieties were subsequently cleaved by acidolysis at pH 2.5 and 105 °C.

Recently, the use of nanoparticles in Wood Plastic Composites (WPCs) has been considered by researchers. In this study, Multi-Walled Carbon Nanotubes (MWCNTs) were compounded with PVC, wood-flour, and foaming agent in an internal mixer. The wood flour amount was constant at 40 phr. For CNT and chemical foaming agent , different levels of 0, 1, 2 phr and 0, 3, 6 phr were considered respectively. The samples were foamed via batch process using a compression molding machine at 180°C. Morphology, density, water absorption, thickness swelling, and tensile properties of foamed composites were evaluated as a function of CNT and chemical foaming agent contents. The experimental results indicated that in the presence of CNT, cell density increased and cell size decreased. Density of the foamed composites was not affected by chemical foaming agent contents. Water absorption and thickness swelling of samples were decreased as compared with wood plastic composite without CNTs. Also, the maximum tensile strength and modulus were increased by up to 20% and 23% respectively.