NC State
  • Researchpp 5086-5098Si, C.-L., Lu, Y.-Y., Qin, P.-P., Sun, R.-C., and Ni, Y.-H. (2011). "Phenolic extractives with chemotaxonomic significance from the bark of Paulownia tomentosa var. tomentosa," BioRes. 6(4), 5086-5098.AbstractPDF
    Chemotaxonomy, also known as chemosystematics, can be regarded as a hybrid science which can classify plants based on their unique extractives (secondary metabolites). In this work, we investigated the chemotaxonomic marks of Paulownia species by studying the extractives of Paulownia tomentosa (Thunb.) Steud. var. tomentosa, a hardwood species widely used in Chinese medicine and pulping industries. Nine phenolic extractives, including two flavonoids (naringenin (1), and quercetin (2)), two phenolic acids (cinnamic acid (3), and gallic acid (4)), and five phenylpropanoid glycosides (cistanoside F (5), acteoside (6), isoacteoside (7), campneoside II (8), and isocampneoside II (9)), were isolated from the n-BuOH soluble fraction of P. tomentosa var. tomentosa bark, by repeated sephadex LH-20 open column chromatography coupled by Thin Layer Chromatography detection. The structures of the phenolic extractives were elucidated and characterized on the basis of their spectroscopical data and physiochemical properties. This was the first time to report the nine extractives from P. tomentosa var. tomentosa bark. Our chemotaxonomic analysis demonstrated that phenylpropanoid glycosides in P. tomentosa var. tomentosa were interesting and phenylpropanoid glycosides may possibly be considered as a useful chemotaxonomic marker within the species of Paulownia.
  • Researchpp 5099-5109Zhang, H., Yuan, Z., Gilbert, D., Ni, Y., and Zou, X. (2011). "Use of a dynamic sheet former (DSF) to examine the effect of filler addition and white water recirculation on fine papers containing high-yield pulp," BioRes. 6(4), 5099-5109.AbstractPDF
    With increased interest in using high-yield pulps (HYP) in uncoated and coated wood-free paper, Such tests were carried out by means of a Dynamic Sheet Former (DSF) sheet with white water recirculation, considering the high fines content of HYP and the usually high filler content in fine papers. In this study, we evaluated the use of a DSF that is equipped with a white water recirculation tank for making oriented sheets under various conditions. The effects of different factors such as operational variables, use of retention aids, and recirculation of white water were examined and clarified in terms of retention of fines and fillers as well as their impact on paper properties. The effect of HYP content on filler retention was also examined.
  • Researchpp 5110-5120Mahdavi, M., Ahmad, M. B., Haron, M. J., Rahman, M. Z. A., and Fatehi, A. (2011). "Optimized conditions for graft polymerization of poly(acrylamide) onto rubberwood fibre," BioRes. 6(4), 5110-5120.AbstractPDF
    Graft copolymerization of acrylamide (Am) onto rubberwood fibre (RWF) was carried out by free radical initiation. Ceric ammonium nitrate was used as an initiator system. The effects of temperature, dose of initiator, ratio of monomer to fibre, and nitric acid concentration, on the grafting percentage were investigated. The optimum reaction temperature was found to be about 50°C for 4h and with an appropriate ratio of monomer to fibre of 3:1 wt/wt. The optimum concentration of initiator and nitric acid were 0.007 M and 0.2 M, respectively. The polyacrylamide (PAm) homopolymer was removed from the graft copolymer by Soxhlet extraction using distilled water. The pre-treatment RWF before the grafting procedure showed that grafting of acid-treated had a higher efficiency than alkali- treated and untreated RWF. Fourier transform infrared spectroscopy was used to confirm and characterize the PAm-graft-RWF.
  • Researchpp 5121-5138Lappi, H. E., and Alén, R. J. (2011). "Pyrolysis of crude tall oil-derived products," BioRes. 6(4), 5121-5138.AbstractPDF
    Crude tall oil (CTO) soap, purified and neutralised CTO, and neutralised distilled tall oil (DTO) were pyrolysed (at 750ºC for 20 s) by pyrolysis gas chromatography with mass-selective and flame ionisation detection (Py-GC/MSD and FID) to clarify their thermochemical behaviour. In each case, the pyrolysates were characteristically dependent on the feedstock, and a wide range of volatile aliphatic and aromatic compounds with some chemically bound oxygen formed. The CTO soap pyrolysate was typically composed of initial extractives-type compounds together with a significant amount of unsaturated aliphatic hydrocarbons and aromatics, whereas the DTO pyrolysate contained mostly just unsaturated aliphatic hydrocarbons and aromatics. These data are of importance when considering the suitability of various extractives-derived resources for producing bioliquids and chemicals.
  • Researchpp 5139-5150Hart, P. W., Colson, G. W., Antonsson, S., and Hjort, A. (2011). "Impact of impregnation on high kappa number hardwood pulps," BioRes. 6(4), 5139-5150.AbstractPDF
    Mixed US southern hardwood chips were impregnated and cooked under various conditions in the laboratory. Kappa numbers between 15 and 55 were obtained. The reject content, kappa number, and yield were studied as a function of time, temperature, and alkali charge in the cooking. The results indicate that by using modern cooking technology, i.e. CompactCookingTM, an optimal point with respect to the studied pulp parameters can be found. Selected pulps were bleached to high brightness with several different bleaching sequences. These pulps were beaten in a PFI mill and their physical properties were compared at a constant bulk. High kappa, well impregnated fully bleached pulps exhibited improved yield with equivalent or better physical properties as compared to conventional kraft pulps. The high kappa, well impregnated pulps were also found to have improved bleachability as compared to conventionally cooked, bleachable grade kappa number pulps.
  • Researchpp 5151-5166Shi, Z.-J., Xiao, L.-P., Deng, J., Xu, F., and Sun, R.-C. (2011). "Isolation and characterization of soluble polysaccharides of Dendrocalamus brandisii: A high-yielding bamboo species," BioRes. 6(4), 5151-5166.AbstractPDF
    Nine soluble polysaccharide fractions were sequentially extracted with hot water at 80, 100, and 120 °C for 3 h, and 60% aqueous ethanol containing 0.25, 0.50, 1.00, 2.00, 3.00, and 5.00% NaOH at 80 °C for 3 h from dewaxed bamboo (Dendrocalamus brandisii) sample, and their chemical compositions and physicochemical properties were examined. The sequential treatments yielded 20.6% soluble polysaccharides of the dry dewaxed bamboo material. Molecular weight and neutral sugars analysis revealed that the soluble polysaccharides were mainly composed of arabinoglucuronoxylans and amylose starch. Spectroscopy (FT-IR, 1H, 13C, and 2D-HSQC NMR) analyses suggested that the isolated arabinoglucuronoxylans from bamboo (D. brandisii) could be defined as a linear (1→4)-β-linked-xylopyranosyl backbone to which α-L-arabinofuranose units and/or short chains of 4-O-methyl-glucuronic acid were attached as side residues via α-(1→3) and/or α-(1→2) linkages. In addition, it was found that the thermal stability of polysaccharides increased with an increment of their molar mass.
  • Researchpp 5167-5179Gao, Z., Ma, D., Lv, X., and Wang, Q. (2011). "Formation and evaluation of kraft fibre-reinforced unsaturated polyester (UPE) composites," BioRes. 6(4), 5167-5179.AbstractPDF
    The effects of moulding pressure and initiator content on the performances of kraft fibre-reinforced UPE composites were investigated by means of tensile evaluation, DMA analysis, SEM analysis, and short-term creep tests. The results indicated that the prepared composites had much higher tensile strength and modulus and better creep resistance than traditional thermoplastic wood plastic composites (WPCs). These improved properties resulted from the incorporation of the strong kraft fibres as reinforcement. The combination of the fibers with the thermosetting UPE matrix produced enhanced kraft-UPE interfacial adhesion. Changes in moulding pressure and initiator level produced various effects in the properties of composites. As the moulding pressure increased from 6 MPa to 25 MPa, the mechanical properties and creep resistances increased gradually until a moulding pressure of 20 MPa was reached; after this point, the values decreased. With an increase in the initiator content from 0.3 PHR (parts per hundred parts of resin) to 1.0 PHR, the tensile strength and interface adhesion first increased, then decreased, while the instantaneous strain and maximum strain values (measured in the creep tests) decreased gradually.
  • Researchpp 5180-5192Safdari, V., Khodadadi, H., Hosseinihashemi, S. K., and Ganjian, E. (2011). "The effects of poplar bark and wood content on the mechanical properties of wood-polypropylene composites," BioRes. 6(4), 5180-5192.AbstractPDF
    Bark, as a residue from trees, is mostly used for thermal energy production, but a better utilization of this resource was considered as an alternative raw material for wood-plastic composites (WPCs). The influence of bark, wood, and blending of bark and wood flour content of the poplar tree on the mechanical characteristics of WPCs were investigated. Wood and bark flours with 2% maleic anhydride-grafted polypropylene (MAPP) and polypropylene were compounded into pellets using a counter-rotating twin-screw extruder, and test specimens were prepared by injection molding. The results showed that both bark fiber and wood flour increased mechanical strength (flexural strength (MOR), flexural modulus (MOE), tensile modulus, and tensile strength) significantly (P<0.05). Composites made with bark flour exhibited lower mechanical strength compared to those made with wood flour and wood flour/bark flour. Differences in chemical composition between bark and wood, fines, low aspect ratio (length/width) of bark flour, delamination between fines and matrix, and the lower intrinsic fiber strength of bark fibers compared to wood fibers are good explanations for this demarcation. The notched impact strength of all reinforced composites was significantly lower than neat polypropylene (P < 0.05).
  • Researchpp 5193-5205Aslanzadeh, S., Taherzadeh, M. J., and Sárvári Horváth, I. (2011). "Pretreatment of straw fraction of manure for improved biogas production," BioRes. 6(4), 5193-5205.AbstractPDF
    Pretreatment of straw separated from cattle and horse manure using N-methylmorpholine oxide (NMMO) was investigated. The pretreatment conditions were for 5 h and 15 h at 120 °C, and the effects were evaluated by batch digestion assays. Untreated cattle and horse manure, both mixed with straw, resulted in 0.250 and 0.279 Nm3 CH4/kgVS (volatile solids), respectively. Pretreatment with NMMO improved both the methane yield and the degradation rate of these substrates, and the effects were further amplified with more pretreatment time. Pretreatment for 15 h resulted in an increase of methane yield by 53% and 51% for cattle and horse manure, respectively. The specific rate constant, k0, was increased from 0.041 to 0.072 (d-1) for the cattle and from 0.071 to 0.086 (d-1) for the horse manure. Analysis of the pretreated straw shows that the structural lignin content decreased by approximately 10% for both samples and the carbohydrate content increased by 13% for the straw separated from the cattle and by 9% for that separated from the horse manure. The crystallinity of straw samples analyzed by FTIR show a decrease with increased time of NMMO pretreatment.
  • Researchpp 5206-5223Abdul Khalil, H. P. S., Marliana, M. M., and Alshammari, T. (2011). "Material properties of epoxy-reinforced biocomposites with lignin from empty fruit bunch as curing agent," BioRes. 6(4), 5206-5223.AbstractPDF
    Lignin was obtained from black liquor samples from soda-AQ pulping of oil palm empty fruit bunch (EFB) fiber. Oil palm EFB reinforced epoxy composite samples with varying lignin content of 15, 20, 25, and 30% as curing agent were prepared. The chemical structures of lignin were characterized by FT-IR, and CHN analysis. FT-IR and CHN analysis confirmed structural changes of epoxy resin after use of EFB-lignin as curing agent in epoxy resin. Thermal analysis of composites was carried out by thermogravimetric analysis (TGA). The TGA graphs showed that crosslinking of epoxy and lignin as curing agent may induce relatively high-chain rigidity in the polymer and may result in an enhanced thermal stability of the EFB/lignin-epoxy composite systems. The mechanical properties (tensile, flexural, and impact behavior) and physical properties (water absorption) of the composite samples were evaluated. Mechanical properties of epoxy composites cured with 25% lignin were found to be higher than that of the composite prepared from a commercial curing agent. Scanning electron micrographs showing tensile fracture of the composites showed evidence of good fiber–matrix interaction, induced by the curing agent.