Research Articles

Effects of alkali treatment of rice straw flour on the mechanical properties of rice straw flour-polypropylene composites were investigated. Rice straw flour (40 mesh) was first treated with sodium hydroxide using two concentrations of sodium hydroxide, 5 and 10% (W/W), and two treatment times (45 and 90 min) for a total of four treatments. The composites were then made with the rice straw flour as a filler (30%), polypropylene (65%) as a matrix, and maleic anhydride (5%) as a coupling agent. The polypropylene/rice straw flour mixtures were blended in an internal Haake mixer and made into molds that were later used for mechanical testing. The results showed that the treatment of rice straw flour with 5% alkali (W/W) increased the tensile modulus and impact strength. Longer treatment time also resulted in a higher tensile modulus and impact strength. The fiber/matrix interaction was analyzed from the mechanical data and morphological (SEM) studies. Treatment of rice straw flour with 10% alkali (W/W), however, decreased these properties even under a longer treatment time. Increasing the alkali concentration and treatment time increased the flexural modulus, flexural strength, and tensile strength of the composites. The SEM results showed greater adhesion between the rice straw flour and the polypropylene matrix at higher alkali concentrations and longer treatment times.

The effects of different circular saws on surface roughness were determined for heat-treated wood, including Scots pine (Pinus sylvestris L.), eastern beech (Fagus orientalis L.), Uludağ fir (Abies bornmülleriana Mattf.), and sessile oak (Quercus petraea L.), which are used commonly in Turkey. Samples were heat-treated for 3, 5, or 7 hours at 140 or 160ºC, and cut with circular saws with 28, 48, 60, 72, or 96 teeth. Then, the surface roughness of the samples was determined using a scanning device (TIME TR200) with respect to the ISO 4287 standard. Heat treatment increased the surface roughness of the wood used, and changed the colour of the wood. To obtain smooth surfaces with or without heat treatment, a circular saw with 28 teeth and a double chamfered (WZ) mouth profile is recommended.

Surface treatment is an important step of papermaking, namely for improving the final product quality. For uncoated printing and writing papers (P&W), surface sizing is becoming a common practice for controlling paper surface characteristics and liquid spreading and absorption. This work aims at evaluating the potential of assessing and controlling paper surface chemistry, by analyzing the impact of the application of different surface sizing formulations both on the chemical surface characteristics of the modified paper samples and on the final printing quality. For that, blends of cationic starch and minor quantities (5%, 10%, and 20% w/w) of four distinct copolymers of styrene were used, resulting in a total of 12 different surface sizing formulations. A sample surface sized only with cationic starch was taken as reference. Surface chemical properties were determined by using contact angle measurements and inverse gas chromatography. Finally, the inkjet printing quality was evaluated. The results revealed that the surface sizing treatments tested have a substantial influence on the surface energetics and partially explain the differences detected in the inkjet printing quality.

Scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy were used for determination of morphology, crystal structure, and surface chemical groups. Thermal behavior was analyzed by thermogravimetric analysis. can induce cellulose folding, surface erosion, and , together with the shorter average length of NCC (96 nm) than that prepared without ultrasonication (150 nm). Due to the smaller size and larger number of free ends of chains, the thermal stability of NCC was lower than BSKP. The degradation of BSKP exhibited one significant pyrolysis stage within the range of 300 to 420 °C. In contrast, UH-NCC exhibited three pyrolysis stages within the range of 210 to 450 °C. NCC prepared with ultrasonication decomposed at lower temperature and over a wider temperature range, together with higher char yield of 43% (compared with 27% for that without ultrasonication). The obtained NCC had similar (74%).

Empty fruit bunches (EFB) from palm oil were characterized. The holocellulose (66.97%), α-cellulose (47.91%), and lignin (24.45%) are similar to wood materials, and various non-wood materials, but the fiber length is shorter (0.53 mm). The influence of operational variables in the EFB pulping [formic acid (75-95%), hydrochloric acid (0.05-0.15%), and time (30-150 min)], on the yield, kappa number, viscosity, and brightness of the pulps was studied. By using a factorial design, equations that reproduced the experimental results for the dependent variables, errors less than 10% were obtained. These equations could be used to find suitable conditions, so that operating with not too high values of operating variables (with minor costs of capital and of operation), pulps could be obtained with acceptable properties. In this way, a cellulosic pulp with a 42.3% yield, 22.7% brightness, and a 512 mL/g viscosity was obtained under the following conditions: 92.5% of formic acid, 0.075% of hydrochloric acid, and a time of 60 min. A pulp (31.1 kappa number and 606 mL/g viscosity) was bleached by EPabOPoP sequence, achieving a brightness of 69.4%, a loss of viscosity and yield of 34.8% and 13.1%, respectively. The residual liquor from the pulping with formic acid 95%, 0.05% hydrochloric acid and 30 min, provides a liquor with 18.2% residual lignin, 4.1% glucose, 9.8% xylose, and 1.2% arabinose, all on dry weight of original material.

Xylose-extracted corncob residue (X-ER), a byproduct from the xylose production industry, is a potential cellulose-rich energy resource. However, attempts to achieve large-scale production of cellulosic ethanol using X-ER have been unsatisfactory due to a lack of understanding of the substrate. This study presents the first characterization of the X-ER to evaluate its potential utilization in the sequential production of cellulosic ethanol. The current dilute acid treatment procedures used for the corncobs by the xylose-production industry were insufficient for efficient deconstruction of cellulose structure to release available sugars for subsequent cellulosic ethanol conversion. After a secondary dilute acid hydrolysis of the X-ER, an additional 30% hemicellulose was recovered. In addition, a more efficient enzymatic hydrolysis of X-ER was observed resulting in a significantly higher yield of glucose conversion compared with an untreated X-ER control. These results suggest X-ER can be utilized for cellulosic ethanol production. However, improved corncob pretreatment procedures are needed for economical cellulosic ethanol conversion.

A novel manganese peroxidase (MnP) produced by an indigenous white rot fungal strain Trametes versicolor IBL-04 in solid state medium of corncobs was purified and characterized. The fungus produced 964U/mL MnP in the presence of additional carbon (glucose) and nitrogen (yeast extract) supplements added at a C:N ratio of 25:1, 1mM Tween-80 (1mL), 1mM MnSO4 (1mL), and 1mM CuSO4 (1mL). The MnP was purified by ammonium sulfate fractionation (65% saturation) and dialysis, followed by Sephadex G-100 gel filtration chromatography. Purification procedures resulted in 2.4-fold purification with an overall yield and specific activity of 3.4% and 660 U/mg, respectively. The purified MnP was monomeric of molecular weight of 43 kDa, showing a single band on sodium dodecyl sulfate poly acrylamide gel electrophoresis (SDS-PAGE). The enzyme was optimally active at pH 5 and 50oC and was stable for 1 h over a broad range of pH (4-7) and temperature (40-65oC). Kinetic constants KM and Vmax of purified MnP were 70 µM and 540 U/mL for MnSO4 substrate. The effect of possible activators and inhibitors of enzyme were also investigated, and it was observed that EDTA, Cystein, and Ag+ caused MnP inhibition and inactivation to different extents, whereas MnP was activated by 4 and 3 mM of Cu2+ and Fe2+, respectively. High thermo-stability, low KM and high Vmax features of this novel MnP isolated from culture filtrate of T. versicolor IBL-04 suggests its suitability for various industrial and biotechnological applications.

Finland currently has tremendous enthusiasm to increase decentralised pellet production alongside of large-scale factories. The aim of research is to promote the development of eco-/cost-efficient Nordic wood-based pellet production by means of multidisciplinary research. Using Finnish conifer stem wood (bark-free Scotch pine sawdust and shavings) as a model raw material, the total functionality of a pilot-scale pellet facility combined with an extensive chemical toolbox was tested in this study to promote future development of eco- and cost-efficient wood-based pellet production in both quantitative and qualitative senses. Lignosulphonate, residual potato flour, and potato peel residue were used as adhesive binding agents. A pilot-scale pellet facility was equipped with a data logger for temperature and power measurements. The chemical toolbox included also novel specific staining and optical microscope methods and respirometric BOD Oxitop measurements. The results showed that adhesive binding agents increased the quality of pellets and changed inorganic characteristics, but did not have a significant effect on their calorimetric heat values. Lignosulphonate even increased the rate of production. Valuable information about both the pelletizing process and pellets is necessary in the future when developing good-quality pellets, a prime biofuel, from low-value and/or moist biomass that has undergone a cost-efficient drying process.

In order to determine the quantitative relationship between sheet strength and lignin coverage at the fiber surface, CTMP was blended with softwood bleached kraft pulp (BKP), refined softwood BKP, and hardwood BKP. The morphology of the fibers, fibers properties, fiber surface components and relative bonded area of sheets were investigated. Multi-linear regression equations of tensile strength index and internal bond strength were established. The results indicated that unbleached aspen CTMP fiber surfaces were covered by granules of lignin, and BKP fiber surfaces were predominated covered by microfibrils. Fiber properties have a significant impact on tensile strength index. RBA had a greater impact on IBS than lignin coverage. For the pulp samples tested, a 1% increase in lignin coverage at fiber surfaces would lead to a 0.48N·m/g decrease in tensile strength index and 5.32×10-3 J/m2 decrease in internal bond strength.

Microfibrillated celluloses (MFCs) have mechanical properties sufficient for packaging applications, but they lack water vapor barrier properties in comparison to petroleum-based plastics. These properties can be modified by the use of mineral fillers, added within the film structure, or waxes, as surface coatings. In this investigation it was found that addition of fillers resulted in films with lower densities but also lower water vapor transmission rates (WVTR). This was hypothesized to be due to decreased water vapor solubility in the films. Associated transport phenomena were analyzed by the Knudsen model for diffusion but due to the limited incorporation of chemical factors in the model and relatively large pore sizes, accurate prediction of pore diameters for filled films was not possible with this model. Modeling the filled-films with Fick’s equation, however, takes into account chemical differences, as observed by the calculated tortuosity values. Remarkably, coating with beeswax, paraffin, and cooked starch resulted in MFC films with water vapor transmission rates lower than those for low density polyethylene. These coatings were modeled with a three-layer model which determined that coatings were more effective in reducing WVTR.