NC State
  • Researchpp 107-116Mishra, P. K., Gregor, T., and Wimmer, R. (2017). "Utilising brewer's spent grain as a source of cellulose nanofibres following separation of protein-based biomass," BioRes. 12(1), 107-116.AbstractArticlePDF

    A multistage process was employed to obtain value-added products from brewer’s spent grain (BSG). This paper is focused on the production and characterisation of cellulose nano-fibres (CNF) as one of the products obtained during the complete process. In the first stage, protein-rich liquor was separated via the alkaline (NaOH) treatment of dried BSG and stored for further utilisation. In the second stage, bleaching treatments were conducted to separate cellulose, which was later converted to CNF by high-pressure homogenisation. The lignocellulosic product from each step was analysed for its chemical composition by means of alkaline hydrolysis combined with the HPEAC method. The thermal properties were measured using thermogravimetric analysis (TGA). The morphology was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). X-ray diffraction (XRD) was done to observe changes in crystallinity. The nano-cellulose produced can be regarded as a value-added material from the bio-refinery of BSG along with numerous already-reported products.

  • Researchpp 117-142Žlahtič, M., and Humar, M. (2017). "Influence of artificial and natural weathering on the moisture dynamic of wood," BioRes. 12(1), 117-142.AbstractArticlePDF

    Wood that is used in outdoor applications is frequently exposed to weathering and is thus prone to fungal degradation. Ways to prevent fungal degradation include keeping the wood dry. The majority of hydrophobic and wood modification systems have been tested only on freshly treated wood. Little information is available on how various wood-based materials perform after a certain period of weathering. To elucidate this question, 17 wood samples were tested from the following species: oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica). Moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. Specimens were exposed to various degradation-aging factors (blue stain fungi, decay fungi, artificial weathering, and natural weathering). Various moisture performance tests were applied before and after aging: short-term water uptake (tensiometer), long-term water uptake, water vapor tests, drying tests, etc. The water exclusion efficacy of wood was decreased after aging. Aging factors were found to act synergistically and to have a more prominent influence on less durable wood compared to durable or preservative-treated wood. Wax-treated wood performed best, regardless of which moisture performance test was applied.

  • Researchpp 143-156Nejad, M., Shafaghi, R., Pershin, L., Mostaghimi, J., and Cooper, P. (2017). "Thermal spray coating: A new way of protecting wood," BioRes. 12(1), 143-156.AbstractArticlePDF

    Thermal spray technology was used to apply a thin layer of copper (Cu metal as an antimicrobial coating) on the surfaces of a number of different solid woods and medium-density fiberboard (MDF) wood composites. The adhesion of a Cu coating to Swietenia macrophylla (mahogany), Quercus (oak), Acer saccharinum (silver maple), Picea (spruce), Pinus strobus (white pine), and MDF was evaluated by a pull-off adhesion test. The resistance of Cu-coated samples to mildew, decay fungi, and water uptake was assessed in the lab. Also, the weathering performance of Cu-coated untreated and heat-treated spruce was evaluated. After proper surface preparation, the adhesion of Cu coatings to hardwood and softwood samples was considered very good, and the adhesion of the Cu coating to MDF was much stronger than the internal bond strength of MDF itself. The Cu coating effectively protected the wood from decay fungi and mildew, while it had no effect on the rate of water absorption and desorption from the wood. After one year of natural weathering in Toronto, Canada, the Cu-coated heat-treated spruce samples had significantly fewer checks than coated, untreated wood. Thermal spray copper coating proved to have the potential to protect wood from biological degradation while also serving as an antimicrobial coating.

  • Researchpp 157-167Kunthiphun, S., Phumikhet, P., Tolieng, V., Tanasupawat, S., and Akaracharanya, A. (2017). "Waste cassava tuber fibers as an immobilization carrier of Saccharomyces cerevisiae for ethanol production," BioRes. 12(1), 157-167.AbstractArticlePDF

    Waste cassava tuber fibers (wCTF), derived from the ethanolic fermentation of cassava tubers, have potential use as anatural adsorption immobilization carrier. Ethanol fermentation was conducted using 15% (w/v) glucose-containing mediumat 40 °C for 48 h by Saccharomyces cerevisiae G6-2-2 (1.3 x 1010cells). Ethanol concentration produced by free, wCTF (1.2 g dry weight) adsorbed, wCTFadsorbed-calcium alginate entrapped,and calcium alginate entrapped cellswere 42.10 ± 0.61, 67.35 ± 0.53, 52.10 ± 0.40, and 46.45 ± 0.18 g/L (0.34, 0.45, 0.35, and 0.31 g ethanol/g reducing sugar), respectively. The wCTF adsorbed cells produced a maximum ethanol yield of 82.15 ± 0.48 g/L (0.43 g ethanol/g total sugar) from molasses (20% w/v initial total sugar) after 48 h, compared to 74 g/L to 76 g/L and 48 h to 100 h for the free suspension cells. The increase in ethanol produced by the wCTF adsorbed cells compared to free cells reflected that the cells were protected from environmental stresses and received amino nitrogen from the wCTF that supported growth and ethanol tolerance.

  • Researchpp 168-182Watchman, M., Potvin, A., and Demers, C. M. H. (2017). "Wood and comfort: A comparative case study of two multifunctional rooms," BioRes. 12(1), 168-182.AbstractArticlePDF

    Many environmental advantages of wood in buildings have been thoroughly documented; however, this material’s effects on occupants are not well known or fully comprehended. This research aims to study comfort parameters in a multifunctional room characterised by extensive wood surfaces in comparison with a similar room with more conventional surfaces at Laval University, Quebec, Canada. The objectives of this research focus on determining the thermal, visual, and acoustical similarities and differences between two rooms using on-site surveys. Analysis of instrumental measurements and images of each room’s indoor environment under overcast skies determined the colour and texture of the surfaces. Quantitative and qualitative analyses revealed that both rooms share similar thermal and acoustic comfort parameters, but have contrasting visual characteristics. The colour, knots, and grain of the wood contributed to producing visually warm experiences resulting in a yellowish room, whereas a mix and match of artificial finishes generates a colder, bluish ambiance in the other room. The conclusion suggests that architects and designers should consider the indoor use of wood for its unique visual ambiances that enhance comfort levels.

  • Researchpp 183-194H’ng, Y. Y., Nakagawa-Izumi, A., Leh, C. P., Das, A. K., and Ohi, H. (2017). "Characterization of residual lignin obtained by the enzymatic hydrolysis of oil palm empty fruit bunch pulps," BioRes. 12(1), 183-194.AbstractArticlePDF

    Residual lignin present in alkali pulps prepared from oil palm (Elaeis guineensis) empty fruit bunch was isolated using an enzymatic method and characterized successfully by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). These pulps were prepared by soda-anthraquinone (AQ) and prehydrolysis (PH) soda-AQ cooking methods (pulp yields were 45.3 and 33.9%, respectively). Py-GC/MS of the residual lignin showed that two pyrolysis products which were indole and methylindole originating from the enzyme (contents 12 to 44%), in addition to eight pyrolysis products originating from syringyl (S) and guaiacyl (G) structure of lignin. Furthermore, palmitic acid was also detected in the residual lignin (contents 0.11 to 0.28%). The residual lignin was subjected to further purification by a cellobiose treatment method, and the quantity of enzyme present in the residual lignin was found to decrease after the treatment. Residual lignin in PH-soda-AQ pulp exhibited a higher S/G ratio (0.86 to 0.98) than that in soda-AQ pulp (0.76 to 0.97). This study showed that the contents of lignin (19 to 44%) and enzyme in enzymatically isolated lignin can be estimated by the Py-GC/MS method.

  • Researchpp 195-210Guo, H., Du, L., Liang, J., Yang, Z., Cui, G., and Zhang, K. (2017). "Influence of alkaline-thermal pretreatment on high-solids anaerobic digestion of dewatered activated sludge," BioRes. 12(1), 195-210.AbstractArticlePDF
    The influence of alkaline (23.77 mg NaOH/g total solid), thermal (134.95 °C), and combined alkaline-thermal pretreatment on parameters of dewatered activated sludge (DAS) during high-solids anaerobic digestion was investigated. Soluble chemical oxygen demand (SCOD), soluble proteins, and VFAs (volatile fatty acids) concentrations were significantly higher (by two-fold) in pretreated DAS samples than in the control. During subsequent anaerobic digestion, the concentrations first increased and then decreased. Total chemical oxygen demand (TCOD) decreased by 28.40% to 40.92%, and ammonia nitrogen accumulated during anaerobic digestion. For the alkaline, thermal, and alkaline-thermal pretreatments, daily methane yield significantly increased in mid-anaerobic digestion and cumulative methane yield (CMY) increased by 9.92, 35.25, and 52.95%, respectively, relative to the control. There were clear synergistic effects of alkaline-thermal pretreatment, resulting in a 17.20% increase in CMY compared with the sum of the separate alkaline and thermal pretreatments. Therefore, alkaline-thermal pretreatment was helpful for high-solids anaerobic digestion of DAS and was an effective pretreatment method. Gompertz model fitting to the CMY curve produced determination coefficients (R2) greater than 0.9931 for all pretreatments, which was better than for a first-order kinetic model fitting curve.
  • Researchpp 211-227Karthikeyan, R., Tjong, J., Nayak, S. K., and Sain, M. M. (2017). "Mechanical properties and cross-linking density of short sisal fiber reinforced silicone composites," BioRes. 12(1), 211-227.AbstractArticlePDF

    In the low cost application of vacuum casting in rapid prototyping, a mould cavity with high modulus is necessary for producing plastics parts in small quantity. In this work, a silicone matrix was reinforced with natural fibers to improve the modulus of composites to mould and to reduce the cost of silicone materials. Sisal fiber with different compositions was reinforced with silicone in a compression moulding process. Mechanical properties were studied. An increase in tensile strength, tear strength, and better hardness was observed in sisal fiber composites . The silane-treated fiber improved the adhesion between fiber and matrix and enhanced the mechanical properties of the composites. The swelling method was adopted to determine the cross-linking density of composites through the Flory-Rehner equation. The flexibility of silicone composites decreased for higher fiber loading and there was an increase in cross-linking of the fiber network to improve modulus of the composites. A morphological study was conducted using X-ray tomography and scanning electron microscopy (SEM) to predict the defects, orientation, debonding, fractography, and interfacial adhesion of fiber/matrix composites.

  • Researchpp 228-254Song, W., Wei, W., Li, X., and Zhang, S. (2017). "Utilization of polypropylene film as an adhesive to prepare formaldehyde-free, weather-resistant plywood-like composites: Process optimization, performance evaluation, and interface modification," BioRes. 12(1), 228-254.AbstractArticlePDF
    To develop formaldehyde-free wood-based composites, plywood-like composites (WV/PPF) were prepared using wood veneer (WV) with polypropylene film (PPF) as a novel formaldehyde-free, water-resistant adhesive. To prepare WV/PPF, the effects of hot-pressing conditions (temperature, 165 to 195 °C; pressure, 0.9 to 1.3 MPa; duration, 40 to 70 s/mm; and adhesive dosage between adjacent WVs, 100 to 200 g/m2) were investigated. Results showed that conditions at 180 °C, 0.9 MPa, 70 s/mm, and 150 g/m2 gave WV/PPF desirable physical-mechanical properties. Then, WV/PPF was compared with plywood-like composites using, respectively, polyethylene film (PEF), urea-formaldehyde resin (UFR), and phenol-formaldehyde resin (PFR) as adhesives. Results showed that the physical-mechanical properties of WV/PPF were favored over WV/PEF and WV/UFR, and were comparable to those of WV/PFR. Maleic anhydride grafted polypropylene (MAPP) or γ-aminopropyltriethoxysilane (APTES) surface modification of WV was performed to enhance the interface compatibility of WV/PPF. Results showed that the physical-mechanical properties of modified WV/PPF were favored over those of WV/PFR; MAPP modification was better for shear properties, while APTES modification was better for dimensional stability and flexural properties. Overall, the environmental and technological benefits demonstrated the potential of WV/PPF as a novel construction and building material.
  • Researchpp 255-269Müller, M., Valášek, P., and Ruggiero, A. (2017). "Strength characteristics of untreated short-fibre composites from the plant Ensete ventricosum," BioRes. 12(1), 255-269.AbstractArticlePDF

    The plant Ensete ventricosum is used in agriculture in Africa. It is a source of fibres, which can be used in the interaction with polymers. This study deals with a material utilization of these fibres with a length of 1 to 2 mm, 2 to 3 mm, and 3 to 5 mm, together with reactoplastics resin ChS Epoxy 1200/324, following requirements of developing countries. Some areas of the African continent suffer from a lack of wood, and material based on epoxy and fibres can substitute for many wood products. The aim of this experiment was to describe basic mechanical properties (tensile strength σm, strain at the break εb, modulus of the elasticity Et, and impact strength an) of the composite material reinforced with fibres of the false banana plant, Ensete ventricosum. The plant, which originated in Ethiopia, is exploitable in developing countries. Geometrical aspects and morphology of the used fibres was characterized by scanning electron microscopy (SEM). The addition of fibres increased the modulus of elasticity and the impact strength, whereas the tensile strength and the strain at break were decreased.