NC State
  • Editorialpp 907-908Treimanis, A. (2009). "Should we be refining first, then discarding fines, then bleaching?" BioRes. 4(3), 907-908.AbstractPDF
    Pulp fibers’ bleaching technology has been developing mainly by applying increasingly intensive delignification in the cooking department and implementation of elemental-chlorine-free chemicals in the bleaching department. The resulting effluents load is still considerable, and the environmental consequences largely depend on the effectiveness of wastewater treatment. Now it is well established that pulp fibers’ surface layers contain comparatively higher amounts of residual lignin, heteroaromatic compounds, and other lignin-like substances. Based on this knowledge an approach is proposed for consideration. As the pulp fibers’ refining process also includes the peeling of fiber wall surface layers, it could be useful to perform such refining first, followed by appropriate screening techniques before the pulp bleaching. The main objection to this approach is related to efficient utilization of the fines, i.e., fractions of the surface layers.
  • Researchpp 909-920Arora, D. S., and Sharma, R. K. (2009). "Enhancement in in vitro digestibility of wheat straw obtained from different geographical regions during solid state fermentation by white rot fungi," BioRes. 4(3), 909-920.AbstractPDF
    The study was carried out to find out the differences in the chemical composition of wheat straw obtained from three different regions of India, to compare their susceptibility to fungal degradation, and subsequently to evaluate the correlation between lignin loss and improvement in in vitro digestibility. Four Phlebia species were used to degrade different wheat straw samples during 30 days of incubation. In wheat straw obtained from central zone of India, most of the fungi were more selective in ligninolysis, with a moderate loss in total organic matter. The best found fungus, P. brevispora,enhanced the in vitro digestibility from 172 to 287 g/kg in north western, 165 to 275 g/kg in north eastern, and 145 to 259 g/kg in central zone with a respective loss of 163, 129, and 105 g/kg in total organic matter. Other three fungi P. fascicularia, P. floridensis, and P. radiata were also able to enhance the in vitro digestibility of all the wheat straw samples up to a significant extent. The study demonstrated that selective ligninolytic behaviour of fungi is influenced by the overall composition of wheat straw as governed by geographic location.
  • Researchpp 921-931Jahan, M. S., and Rawshan, S. (2009). "Reinforcing potential of jute pulp with Trema orientalis (nalita) pulp," BioRes. 4(2), 921-931.AbstractPDF
    Two morphologically different pulps, a long-fiber jute pulp from a soda-AQ process and a short-fiber Trema orientalis pulp from a kraft process, were evaluated and compared for their reinforcing potential. T. orientalis pulp needed less beating energy than jute pulp at the same drainage resistance. Addition of jute fiber pulp to the T. orientalis pulp increased tear strength. Sheet density of pulp blends was increased with the increase of beating degree of both pulps and the proportion of T. orientalis pulp. Tensile index and burst index of blended pulp were increased when the beating degree and proportion of T. orientalis pulp increased.
  • Researchpp 932-945Gupta, V. K., Gaur, R., Yadava, S. K., and Darmwal, N. S. (2009). "Optimization of xylanase production from free and immobilized cells of Fusarium solani F7," BioRes. 4(3), 932-945.AbstractPDF
    The aim of the present investigation was to characterize a xylanase-producing Fusarium solani isolate and to optimize cultural conditions for xylanase enzyme production from free and immobilized cells. Screening of Fusarium solani isolate was based on the diameter of the clear zone formation in oat spelt xylan agar plates. Fusarium solani isolate F7 was selected and optimized for xylanase enzyme production using cheaper substrates such as wheat straw, rice straw, rice bran, and wood husk. Maximum enzyme activity was observed in wheat straw (78.32 U ml-1 for free cells and 94.68 U ml-1 for immobilized cells). Optimum pH and temperature for xylanase activity were found to be 5.5 and 30°C at 3% substrate concentration for free cells and 5.0 and 30°C at 3% substrate concentration for immobilized cells. In the purification step, 75% ammonium sulphate saturation was found to be suitable, giving maximum xylanase activity. Production of xylanase was greater from immobilized cells than from free cells. Purified xylanase from free cells yielded a single band with a molecular weight of 89kDa, while it was 92.8kDa for immobilized cells. The use of wheat straw as a major carbon source is particularly valuable, because oat spelt xylan is very expensive. The Fusarium solani F7 isolate proved to be a promising microorganism for xylanase production.
  • Researchpp 946-959Wang, X.-H., Chen, H.-P., Ding, X.-J., Yang, H.-P., Zhang, S.-H., and Shen, Y.-Q. (2009). "Properties of gas and char from microwave pyrolysis of pine sawdust," BioRes. 4(3), 946-959.AbstractPDF
    Pine sawdust pyrolysis was carried out respectively using microwave and conventional electrical heating at different temperatures in order to understand the properties of pyrolytic products from microwave pyrolysis of biomass. Less char material was obtained by microwave pyrolysis compared to conventional heating at the same temperature. While comparing the components of the pyrolytic gases, it was revealed that the microwave pyrolysis gas usually had higher H2 and CO contents and lower CH4 and CO2 contents than those obtained by conventional pyrolysis at the same temperature. The texture analysis results of the microwave pyrolysis chars showed that the chars would melt and the pores would shrink at high temperatures, and hence, the specific surface areas of the chars decreased with increasing temperature. Similarly, the reactivity of the char was remarkably reduced when the microwave pyrolysis temperature exceeded 600°C.
  • Researchpp 960-969Kurt, Ş., and Özçifçi, A. (2009). "Effect of various fire retardants on Brinell hardness of some wood," BioRes. 4(3), 960-969.AbstractPDF
    This study was performed to determine the impact of impregnation materials on the Brinell hardness of varnished wood materials. For this purpose, test specimens prepared from Scotch pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky), which met the requirements of ASTM D 358, were impregnated according to ASTM D 1413-07 with borax, boric acid, zinc chloride, and di-ammonium phosphate by a vacuum technique. After impregnation, the surfaces were coated by cellulosic, synthetic, and polyurethane varnishes in accordance with ASTM D 3023. The Brinell hardness of the specimens after the varnishing process was determined in accordance with ASTM D 4366. According to the result of the tests, the highest Brinell hardness (135.40 kpm/m²) was determined in oriental beech samples, cut tangentially, impregnated with di- ammonium phosphate, and varnished with polyurethane. The lowest Brinell hardness (23.20 kpm/m²) was determined in Scotch pine control samples, cut radially and synthetically varnished.
  • Researchpp 970-978Abdolzadeh, H., and Doosthoseini, K. (2009). "Evaluation of old corrugated container and wood fiber application on surface roughness of three-layer particleboard," BioRes. 4(3), 970-978.AbstractPDF
    This paper presents the results of a study to use virgin wood and OCC fiber for particleboard production. Three-layer boards, with wood and OCC fiber on the surface, were fabricated. The type of applied furnishes at surface layers, moisture, and adhesive content were considered as variables, and their effects on roughness of manufactured particleboards were examined. The panels were produced with 10% and 12% urea formaldehyde (UF) adhesive at 10% and 14% moisture content. The surface characteristics were investigated. The results indicated that wood and OCC fiber utilization on the surface layer gave smoother surfaces than a control board with fine wood particles on its surface. The surface roughness decreased as adhesive and moisture content increased.
  • Researchpp 979-985Zhou, J., Sui, X., and Shi, H. (2009). "Study on the structural change of lignin during auto-catalyzed ethanol-water pulping of aspen by 1H-NMR," BioRes. 4(3), 979-985.AbstractPDF
    This study concerns the structural change of lignin during auto-catalyzed ethanol-water pulping of aspen by 1H-NMR. The results showed that the linkages of alkyl-aryl ether of lignin, such as the α-ether linkages (α-O-4) and the β-ether linkages (β-O-4), were broken and the alkyl part formed carbenium at the Cα and Cβ of the aliphatic branch. Meanwhile, the aryl part of ether accepted one H+ and formed phenol. Because of the electronegative effect originating from the electron cloud of phenyl, partial carbenium of Cβ was rearranged. Due to its ether or hydroxyl linkage, rearranging to Cβ, the Cα was changed into carbenium and formed a new β-O-4 alkyl-aryl ether. The β-O-4 alkyl-aryl ether was not stable and broken further. So the large molecule of lignin was disintegrated into a smaller one and dissolved into ethanol. Finally, the α+ carbenium reformed α-O-4 linkages of ether with phenol.
  • Researchpp 986-1005Sharma, R. K., and Chauhan, G. S. (2009). "Synthesis and characterization of graft copolymers of 2-hydroxyethyl methacrylate and some comonomers onto extracted cellulose for use in separation technologies," BioRes. 4(3), 986-1005.AbstractPDF
    To develop low-cost and environmentally friendly polymeric materials for enrichment, separation, and remediation of metal ions from water, graft copolymers based on cellulose extracted from pine needles were synthesized by grafting of 2-hydroxy methacrylate (HEMA) alone and with comonomers acrylic acid, acrylamide, and acrylonitrile by benzoyl peroxide initiation. The effects of change in concentrations of monomer and initiator, reaction time and temperature; and nature and composition of solvent system on graft yield and grafting efficiency were evaluated. At the optimum reaction conditions evaluated for the grafting of HEMA alone, comonomers as acrylamide, acrylic acid, and acrylonitrile at their five different concentrations were also co-grafted along with HEMA onto cellulose backbone polymer. Graft copolymers were further functionalized by partial hydrolysis, and were characterized by water uptake, FTIR, and elemental analysis. Sorption of Fe2+, Cu2+ and Cr6+ ions on graft copolymers were investigated to define their end-uses in separation technologies.
  • Researchpp 1006-1016Guo, S., Zhan, H., Zhang, C., Fu, S., Heijnesson-Hultén, A., Basta, J., and Greschik, T. (2009). "Pulp and fiber characterization of wheat straw and eucalyptus pulps - A comparison," BioRes. 4(3), 1006-1016.AbstractPDF
    The response to refining of wheat straw and eucalyptus pulps as well as the relationships between refining, fiber properties, and paper properties are described in this paper. Pulps were bleached applying different bleaching sequences and thereafter refined to varying degrees. Pulp and fiber properties were investigated and set into relation to the final sheet properties. The results show that wheat straw pulps respond to refining more easily than eucalyptus pulps and that the differences are due mainly to morphological and ultrastructural differences as well as fines content and xylan content. The development of strength properties of the different pulps was found to be strongly correlated to the number of dislocations, i.e. weak points in the fiber wall, as well as to the morphological appearance of the pulp fibers after refining. A higher initial number and a faster development of dislocations together with the creation of large amounts of fines explain the slower and lower development of strength properties of wheat straw pulps than of eucalyptus pulps. Removal of fines from wheat straw pulps improved not only the drainability of the pulp suspension but also the mechanical and optical sheet properties. This indicates that the fines in the wheat straw pulps act mainly as filler with low bonding properties. The fact that fractionated D(EOP)D wheat straw pulps can deliver good mechanical sheet properties at very good drainability with no or only minor refining is very interesting when evaluating the potential of replacing or partially replacing eucalyptus with domestic Chinese raw materials in furnishes for production of different paper products.
  • Researchpp 1017-1031Nada, A. M. A., Mahdy, A. A., and El-Gendy, A. A. (2009). "Spectroscopy and chemical studies of cation exchangers prepared from corn cobs,"BioRes. 4(3), 1017-1031.AbstractPDF
    A series of ion exchangers was prepared from corn cobs. Phos-phate, sulfate, phosphosulfonate, and carboxylic groups were incorporated onto the corn cobs. The magnitude of functional groups incorporated onto corn cobs, as well as of the cross-linking, was taken as a measure of reactivity of the produced ion exchanger. The effect of treatment of corn cobs with different concentrations of sodium hydroxide, volume of used pyridine, and efficiency of the produced resin toward metal ions adsorption was investigated. The effect of cross-linking of corn cobs on the incorporation of phosphate group was studied. Sodium binding capacity as well as the adsorbed efficiency of metal ions efficiency as Zn, Pb, Ni, Fe, and Cr by produced resin from corn cobs was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). It was found that the quantity and the type of incorporated functional groups, as well as the type of metal ions, play an important role in the efficiency of resin toward adsorption of metal ions.
  • Researchpp 1032-1043Ates, S., Akyildiz, M. H., and Ozdemir, H. (2009). "Effects of heat treatment on calabrian pine (Pinus brutia ten.) wood," BioRes. 4(3), 1032-1043.AbstractPDF
    In this study, the effects of heat treatment on some physical, mechanical, chemical properties, and cellulose crystallinity of calabrian pine (brutia Ten.) were evaluated. Wood specimens were treated with heat under atmospheric pressure at three different temperatures (130, 180, and 230 oC) and two different time levels (2 and 8 h). Air-dry density (Dm), oven-dry density (D0), shrinkage (β), swelling (α), fiber saturation point (FSP), compression strength parallel to grain (σc//), bending strength (σb), modulus of elasticity (MOE) in bending, equilibrium moisture content (EMC), holocellulose, and alcohol solubility were decreased, whereas 1% NaOH solubility and lignin content were increased, depending on the heating temperature and time. Cellulose crystallinity of the samples was not changed significantly. 130 oC showed a minimal effect; on the other hand, 230 oC showed a maximum effect on all properties of the treated wood. That’s why, for the heat treatment process, 130 oC for 2 h should be applied in situations where mechanical properties such as modulus of elasticity, compression strength, bending strength, and hardness are important. However, 230 oC for 2 h should be used in situations where it is preferred to obtain favorable physical properties, such as density, shrinkage, swelling, and moisture content.
  • Researchpp 1044-1057Chirkova, J., Andersons, B., and Andersone, I. (2009). "Study of the structure of wood-related biopolymers by sorption methods," BioRes. 4(3), 1044-1057.AbstractPDF
    The potentialities of different vapour sorption methods are analized for the investigation of the microstructure of wood sorbents (wood, cellulose and lignin) as a particular case of biopolymers. There are two important distinctions in the sorption behaviour of biopolymers from traditional rigid sorbents, namely, the dependence of the characteristics of the porous structure on the thermodynamic properties of the sorbate, and the manifestation of the sorption hysteresis over the whole region of the sorption–desorption isotherm. The reason for these distinctions is the low rigidity (low values of modulus of elasticity) of biopolymers, hence, their considerable deformability under the action of sorption forces, resulting in the cleavage of interstructural bonds. This process, manifesting itself phenomenologically as swelling, depends on the activity of the sorbate and results in the appearance of porosity and a new surface. The criterion for the activity of the sorbate is close values of the solubility parameters of the polymer and the sorbate. Inert substances are adsorbed on the surface of large morphological formations and characterise the intact structure of the sorbent, while active sorbates cause the swelling of these formations and penetrate them, which enables a study of the microstructure of sorbents. In the desorption process, the cleaved bonds are restored, blocking a part of the sorbate in the polymer’s structure, which results in the appearance of sorption hysteresis, not connected directly with the porous structure of the sorbent.
  • Researchpp 1058-1069Campos, A. C. M., Hein, P. R. G., Mendes, R. F., Mendes, L. M., and Chaix, G. (2009). "Near infrared spectroscopy to evaluate composition of agro-based particleboards," BioRes. 4(3), 1058-1069.AbstractPDF
    Particleboards can be manufactured from particles of any lignin-cellulosic material that can be combined with an adhesive and consolidated under the action of temperature and pressure. Because the raw materials in the industrial process are continually changing, the particleboard industry requires methods for monitoring the quality of their products. Hence, the aim of this paper was to evaluate the composition of the agro-based particleboards by near infrared spectroscopy. In this study, agro-based particleboards produced with different compositions of Eucalyptus and Pinus wood particles and sugar cane bagasse were evaluated by NIR spectroscopy and partial least square (PLS) regression. The PLS models to estimate the Eucalyptus and Pinus particles and sugar cane bagasse contents presented a strong coefficient of determination (0.90, 0.88 and 0.84, respectively), but also high magnitudes of standard errors of cross-validation were observed (ranging from 8.84 to 11.27%). Development work would be required in order to reduce the standard errors and improve predictive model performance to build robust models that could be applied as quality control tool.
  • Researchpp 1070-1087Kumarappan, S., Joshi, S., and MacLean, H. L. (2009). "Biomass supply for biofuel production: Estimates for the United States and Canada," BioRes. 4(3), 1070-1087.AbstractPDF
    The potential supply of biomass feedstocks in the US and Canada is estimated using a static supply function approach. Estimated total biomass available at a price of $100 per metric ton is 568 million metric tons in the US and 123 million tons in Canada, which together can displace 23-45 billion gallons of gasoline. Sufficient biomass, mainly agricultural and mill residues, will be available at prices of around $50/ton to meet the advanced biofuel mandates of the US Energy Independence and Security Act of 2007. The estimates of agricultural residue supply are very sensitive to the assumed fraction of residues that can be sustainably removed from the field, and the potential of municipal solid waste as a feedstock depends on which components can be economically converted into liquid biofuels.
  • Researchpp 1088-1097Kong, F., and Ni, Y. (2009). "Development of cellulosic paper-based test strips for Cr(VI) determination," BioRes. 4(3), 1088-1097.AbstractPDF
    Paper-based test strips specific for the Cr(VI) determination in aqueous solutions were developed by impregnating a color-forming reagent, diphenylcarbazide, and a quaternary ammonium salt (Aliquat 336) into paper sheets. The results showed that the quaternary ammonium salt could effectively retain the colored complex in the paper substrate. This paper-based test strip showed a high selectivity for Cr(VI) in the samples to be tested. The method was applied to synthetic samples, and the results were compared to these from a reference method. The current work demonstrated that with a color chart, this portable paper-based test strip has the potential to be used for field screening or on-site semi-quantitative analysis.
  • Researchpp 1098-1108Yokota, S., Ohta, T., Kitaoka, T., and Wariishi, H. (2009). "Adsorption of cellobiose-pendant polymers to a cellulose matrix determined by quartz crystal microbalance analysis," BioRes. 4(3), 1098-1108.AbstractPDF
    Cellobiose-pendant polymers were synthesized by radical polymerization and their affinity for a cellulose matrix was investigated by quartz crystal microbalance (QCM). A 2-(methacryloyloxy)ethylureido cellobiose (MOU-Cel) macromer was synthesized by coupling cellobiosylamine with 2-(methacryloyloxy)ethyl isocyanate followed by polymerization in an aqueous radical reaction system. The interaction of the resulting poly(MOU-Cel) with a pure cellulose matrix in water was evaluated by QCM analysis. Poly(MOU-Cel) was strongly adsorbed to the cellulose substrate, whereas neither cellobiose nor MOU-Cel macromer exhibited an attractive interaction with cellulose. This specific interaction was not inhibited by the presence of ionic contaminants, suggesting that multiple cellobiopyranose moieties in each polymer molecule might cooperatively enhance its affinity for cellulose. Moderate insertion of acrylamide units into the polymer backbone improved the affinity for cellulose, possibly due to an increased mobility of sugar side chains. Polymers such as these, with a high affinity for cellulose, have potential applications for the surface functionalization of cellulose-based materials, including paper products.
  • Researchpp 1109- 1129Sanghi, A., Garg, N., Kuhar, K., Kuhad, R. C., and Gupta, V. K. (2009). "Enhanced production of cellulase-free xylanase by alkalophilic Bacillus subtilis ASH and its application in biobleaching of kraft pulp," BioRes. 4(3), 1109-1129.AbstractPDF
    This paper reports high level production of a cellulase-free xylanase using wheat bran, a cost-effective substrate, under submerged fermentation by alkalophilic Bacillus subtilis ASH. Production of xylanase was observed even at alkaline pH up to 11.0 and temperature 60 °C, although the highest enzyme titer was recorded at neutral pH and 37 °C. The enzyme production under optimized fermentation was 1.5-fold greater than under unoptimized conditions. Pre-treatment of unbleached pulp of 10% consistency with crude xylanase (6 IU/g o.d. pulp) at 60 ºC for 2 h increased the final brightness by 4.9%. The enzyme treatment reduced the chlorine consumption by 28.6% with the same brightness as in the control. A reduction in kappa number and increase in viscosity was observed after enzyme pre-treatment. Scanning electron microscopy revealed loosening and swelling of pulp fibers. The strength properties viz. grammage, fiber thickness, beating degree, tensile index, breaking length, tear index and double fold of the treated pulp were improved as compared to the control pulp. This study reveals the potentialof B. subtilis ASH xylanase as a biobleaching agent for the paper and pulp industry.
  • Researchpp 1130-1138Bhoria, P., Singh, G., and Hoondal, G. S. (2009). "Optimization of mannanse production from Streptomyces sp. PG-08-03 in submerged fermentation," BioRes. 4(3), 1130-1138.AbstractPDF
    Streptomyces sp. PG-08-3 was isolated from the desert of Rajasthan (India). The organism produced mannanase (15 Umg-1 protein) in the presence of 0.5% guar gum as a sole carbon source in minimal media by submerged fermentation (SmF). Enzyme production was enhanced by 7.3-fold when 0.5% soyabean meal and 0.25% of leucine were added to the minimal media. Increasing the guar gum concentration in the media by 0.1-1.0% resulted in linearly enhanced the production of mannanase.
  • Researchpp 1139-1146Masingale, M. P., Alves, E. F., Korbieh, T. N., Bose, S. K., and Francis, R. C. (2009). "An oxidant to replace nitrobenzene in lignin analysis," BioRes. 4(3), 1139-1146.AbstractPDF
    Four metal organic frameworks (MOFs) are being evaluated as possible catalysts for alkaline lignin oxidation. One aspect of the screening process is the oxidation of in-situ hardwood lignin by a high mole ratio of Cu, Fe, or Cu + Fe contained in the MOFs. The MOF’s were prepared in a microwave-assisted synthesis. One of the MOFs, a benzenetricar-boxylic acid complex of Cu (II) and Fe (III), converted the phenylpropane (C9) units in in-situ poplar lignin to approximately 50% monomers. The ratio of syringyl (S) to guiacyl (G) monomers was similar to the S:G ratio obtained from nitrobenzene oxidation (NBO). The S:G ratio from NBO was then compared to that from MOF oxidation (MOFO) for two other poplars. The S:G ratios for the three poplars by MOFO were 1.20, 1.51 and 1.67, respectively while the corresponding NBO values were 1.25, 1.45 and 1.68. These initial results indicate that MOFO could be developed into a credible replacement for NBO, because it affords a higher yield of monomers when a large MOF dose is used. Some preliminary results are also presented for MOF acting as a catalyst (100 ppm Cu (II) plus 81 ppm Fe (III) in NaOH) for oxygenation of the hardwoods. The products from O2 + MOF are identical to MOF only, but the ratios amongst them are different.
  • Researchpp 1147-1157Zhuang, J., Lin, L., Liu, J., Luo, X., Pang, C., and Ouyang, P. (2009). "Preparation of xylose and kraft pulp from poplar based on formic/acetic acid/ water system hydrolysis," BioRes. 4(3), 1147-1157.AbstractPDF
    A formic/acetic acid/water system was used in the ratios of 30:60:10, 20:60:20, and 30:50:20 separately for efficient hydrolysis and bioconversion of poplar chips, under the solid/liquid ratio of 1:12(g/ml), at 105 oC for 30, 45, 60, 75, and 90 min, respectively. The highest yield of 69.89% was at a formic/acetic acid /water ratio of 30:50:20(v/v/v), with solid/liquid in the ratio of 1:12(g/ml) at 105 oC for 90min. Lower kappa number and similar yield were achieved when hydrolytic residual woodchips were used for kraft pulping with over 2% Na2O and temperature 5 °C lower compared to untreated chips. Pulps from prehydrolysis-treated chips were easy to beat. But the tensile index, tear index, and burst index of the handsheets obtained from pulp with lowest kappa number from prehydrolysis-treated poplar chips were lower than those of the pulp from the untreated chips. Considerable xylose could be obtained from the prehydrolysis stage following kraft pulping under the same conditions for prehydrolysis-treated chips and untreated chips. However, by building on the mature kraft pulping and xylitol processes, large amounts of xylose from the hemicellulose were obtained in prehydrolysis, allowing production of high-valued products via biorefinery pathways. An economical balance of chemical dosage, energy consumption, pulp properties, and xylose value for prehydrolysis with organic acid should be reached with further investigation.
  • Researchpp 1158-1167Hu, J.-J., Lei, T.-Z., Xu, G.-Y., Shen, S.-Q., and Liu, J.-W. (2009). "Experimental study of stress relaxation in the process of cold molding with straw," BioRes. 4(3), 1158-1167.AbstractPDF
    In this article, five kinds of straws were used to do compressing molding experiments on stress relaxation by Electric Versatile Material Machine, with specially designed open mode equipment. According to the data from the transition stage of the compression process, regression equations with different straws were built by selective global fitting or piecewise fitting. In addition, the equations were verified by stress logarithm-time curves. A stress relaxation model of the five straws can be summarized by an expression involving the summation of exponential decay terms. This expression provides reference for reducing the specific energy consumption and increasing the pellet density.
  • Researchpp 1168-1177Ioelovich, M. (2009). "Accessibility and crystallinity of cellulose," BioRes. 4(3), 1168-1177.AbstractPDF
    The accessibility of cellulose samples having various degrees of crystallinity was studied with respect to molecules of water, lower primary alcohols, and lower organic acids. It was found that small water molecules have full access to non-crystalline domains of cellulose (accessibility coefficient α = 1). Molecules of the lowest polar organic liquids (methanol, ethanol, and formic acid) have partial access into the non-crystalline domains ( α <1), and with increasing diameter of the organic molecules their accessibility to cellulose structure decreases. Accessibility of cellulose samples to molecules of various substances is a linear function of the coefficient α and the content of non-crystalline domains. The relationship between crystallinity (X) and accessibility (A) of cellulose to molecules of some liquids has been established as A = α (1-X). The water molecules were found to have greater access to cellulose samples than the molecules of the investigated organic liquids. The obtained results permit use of accessibility data to estimate the crystallinity of cellulose, to examine the structural state of non-crystalline domains, and to predict the reactivity of cellulose samples toward some reagents.
  • Researchpp 1178-1189Shen, J., Song, Z., Qian, X., and Liu, W. (2009). "A preliminary investigation into the use of acid-tolerant precipitated calcium carbonate fillers in papermaking of deinked pulp derived from recycled newspaper," BioRes. 4(3), 1178-1189.AbstractPDF
    The use of acid-tolerant precipitated calcium carbonate fillers, including phosphoric acid/sodium hexametaphosphate modified precipitated CaCO3 filler, and sodium silicate/phosphoric acid/sodium hexametaphos-phate modified precipitated CaCO3 filler in papermaking of deinked pulp derived from recycled newspaper was explored. These two acid-tolerant fillers provided considerably more brightness improvement in papers in comparison the unmodified filler, presumably indicating alleviated pulp darkening achieved as a result of better acid-resistant properties. The addition of acid-tolerant fillers into the furnish slurries gave lower system pH as compared with unmodified filler. Among the three fillers used in this work, the effect on retention of modification of the filler with sodium silicate/phosphoric acid/sodium hexametaphosphate was probably the best, as evaluated from ash content measurements. For air permeability of the paper, the use of acid-tolerant fillers provided slightly more improvement in comparison to the unmodified filler. For tensile and burst strength of the paper, the use of sodium silicate/phosphoric acid/sodium hexameta-phosphate modified precipitated calcium carbonate filler gave better results as compared with the other two fillers. Additionally, the improving effect of acid-tolerant fillers on furnish static drainage was found to be slightly weaker than that of unmodified filler.
  • Reviewpp 1190-1209Shen, J., Song, Z., Qian, X., and Liu, W. (2009). "Modification of papermaking grade fillers: A brief review," BioRes. 4(3), 1190-1209.AbstractPDF
    The use of fillers in paper products can provide cost and energy savings, improved paper properties, increased productivities, and specifically desired paper functionalities. There are many problems associated with the use of fillers, such as unsuitability of calcium carbonate fillers in acid papermaking, negative effects of filler loading on paper strength, sizing, and retention, and tendencies of fillers to cause abrasion and dusting. In order to solve these problems and to make better use of fillers, many methods have been proposed, among which filler modification has been a hot topic. The available technologies of filler modification mainly include modification with inorganic substances, modification with natural polymers or their derivatives, modification with water-soluble synthetic polymers, modification with surfactants, modification with polymer latexes, hydrophobic modification, cationic modification, surface nano-structuring, physical modification by compressing, calcination or grinding, and modification for use in functional papers. The methods of filler modification can provide improved acid tolerant and optical properties of fillers, enhanced fiber-filler bonding, improved filler retention and filler sizabilities, alleviated filler abrasiveness, improved filler dispersability, and functionalization of filled papers. Filler modification has been an indispensable way to accelerate the development of high filler technology in papermaking, which is likely to create additional benefits to papermaking industry in the future.
  • Reviewpp 1210-1221Muszyński, L. (2009). "Imaging wood plastic composites (WPCs): X-ray computed tomography, a few other promising techniques, and why we should pay attention," BioRes. 4(3), 1210-1221.AbstractPDF
    Wood plastic composites are complex, anisotropic, and heterogeneous materials. A key to increasing the share of the WPC materials in the market is developing stronger, highly engineered WPCs characterized by greater structural performance and increased durability. These are achieved by enhanced manufacturing processes, more efficient profile designs, and new formulations providing better interaction between the wood particles and the plastic matrix. Significant progress in this area is hard to imagine without better understanding of the composite performance and internal bond durability on the micro-mechanical level, and reliable modeling based on that understanding. The objective of this paper is to present a brief review of promising material characterization techniques based on advanced imaging technologies and inverse problem methodology, which seem particularly suitable for complex heterogeneous composites. Full-field imaging techniques and specifically X-ray computed tomography (CT) combined with numerical modeling tools have a potential to advance the fundamental knowledge on the effect of manufacturing parameters on the micromechanics of such materials and their response to loads and environmental exposure.
  • Reviewpp 1222-1262Wu, N., Hubbe, M. A., Rojas, O. J., and Park, S. (2009). "Permeation of polyelectrolytes and other solutes into the pore spaces of water-swollen cellulose: A review," BioRes. 4(3), 1222-1262.AbstractPDF
    The rate and extent of transport of macromolecules and other solutes into cellulosic materials and fibers have important applications in such fields as papermaking, textiles, medicine, and chromatography. This review considers how diffusion and flow affect permeation into wood, paper, and other lignocellulosic materials. Because pore sizes within such materials can range from nanometers to millimeters, a broad perspective will be used, also considering some publications related to other porous materials. Factors that limit the rate or extent of polymer or other solute transport into pores can involve thermodynamics (affecting the driving motivation for permeation), kinetics (if there is insufficient time for the system to come to equilibrium), and physical barriers. Molecular flow is also affected by the attributes of the solute, such as molecular mass and charge, as well as those of the substrate, such as the pore size, interconnectedness, restricted areas, and surface characteristics. Published articles have helped to clarify which of these factors may have a controlling influence on molecular transport in different situations.