Research Articles

Large quantities of volatile organic compounds (VOCs) are released from heat-treated bamboo during the manufacturing process of recombinant bamboo, which affects the environment and human health. In this study, bamboo was treated at 150 °C, 180 °C, and 210 °C for 3 h, and VOCs were collected every hour using a Tenax tube. The VOCs were analyzed with gas chromatography-mass spectrometry (GC-MS) to explore the effect of temperature and time on weight loss ratio, main components, and their relative proportions. The results showed that temperature considerably influenced weight loss ratio, and weight loss ratio increased rapidly at high temperature. Massive quantities of VOC were emitted during the first hour of treatment, and emissions decreased as the time and temperature increased. Terpenes were the primary component of the VOC emissions. Temperature and time exhibited minimal effects on the type of primary components, and the relative proportion of some components exhibited negligible changes over a range of temperatures and times.

Poplar wood was subjected to biological treatment with a white-rot fungus Trametes hirsuta C7784. The structural features of the lignin in the untreated and treated poplar wood samples were comparatively elucidated. Milled wood lignin (MWL) and residual enzymatic lignin (REL) fractions of each sample were sequentially isolated. The total pure yields of the isolated lignin fractions after white-rot fungus treatment exceeded 96% (based on the Klason lignin content), and thus, represented the whole lignin in the fungus-treated poplar wood. The structural features of the lignin fractions were quantitatively analyzed. β–O-4′ structures were the most prominent linkage in the biologically treated wood, and there were more present than in the untreated wood. To this effect, the lignin in the fungus-treated poplar wood was easily degraded and removed under mild conditions, which is essential for subsequent conversion processes.

Untreated and hot-water-extracted (HWE) Norway spruce (Picea abies) sawdust was cooked using the sulfur-free oxygen-alkali (OA) method under the following conditions: temperature, 170 °C; liquor-to-wood ratio, 5:1 L/kg; and NaOH charge, 19% on the oven-dry sawdust. In comparison with earlier studies conducted with birch sawdust, the spruce cooking yield data, together with the amount of the pulp rejects (78% to 86% for reference pulps from the initial feedstock and 73% to 83% for pulps from the HWE feedstock), revealed that the pretreatment stage prior to spruce OA pulping caused different effects on pulping performance. The analyses of the three main compound groups (i.e., lignin, volatile acids, and hydroxy acids) in black liquor indicated that slightly higher contents (25.5 to 45.9 g/L) of dissolved lignin were detected in black liquors originating from the HWE sawdust than in the black liquors from the reference material (27.2 to 39.6 g/L). In contrast, considerably lower (~20% decrease) volatile acid contents and similar or slightly decreased hydroxy acids contents were detected in the black liquors from the HWE sawdust.

The objective of this study was to provide fundamental parameters for the utilization of bamboo scrimber in the building structure field as a green building material. Both static tensile and compressive tests were conducted on bamboo scrimber, with 180 specimens for compressive tests and 173 specimens for tensile tests. The normal and lognormal distributions were selected to fit the experimental data. The design values were calculated according to the Chinese allowable stress design method and ASTM D2915 (2003). The results showed that both tensile strength (UTS) and compressive strength (CS) parallel to the fiber of bamboo scrimber were significantly higher than those of wood and other bamboo-based composite materials. Kolmogorov-Smirnov and chi-squared test results indicated that a lognormal distribution was a good fit for the UTS and CS except for the fitting result of UTS by the chi-squared test. The calculated design values of UTS and CS using ASTM D2915 (2003) were higher compared with those found using the Chinese allowable stress design method.

The physical properties of wheat straw treated with hydrothermal and chemical treatments were investigated using an electronic universal testing machine, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The thermal stability of the wheat straw was also investigated using thermogravimetric analysis (TGA). The experimental results showed that the chemical treatment was a main factor governing the enzymatic saccharification of wheat straw. Different treatments of wheat straw had the same mass loss trend. The maximum mass loss occurred in the range between 250 and 400 °C for all straw samples. In this range, the wheat straw treated with NaOH showed an exothermic peak, while samples treated with the other treatments showed an endothermic peak. Chemical treatments disrupted the silicified waxy surface and destroyed the C-O bond. The internal structure of wheat straw treated with NaOH became porous and loose and exposed more accessible surface area of the cellulose to cellulase.

Lignosulfonate and lignosulfonate hydrolyzed under alkaline conditions were used as the polyol components in polyurethane foam formulations. Although the treatment increased hydroxyl group abundance, it did not improve the applicability of hydrolyzed lignosulfonate in polyurethane foam. Thus, the use of original lignosulfonate yielded foams of thermal stability and mechanical properties comparable to other types of bio-based foams (Young’s moduli 0.95 to 4.42 MPa, 50% weight loss, and temperature ca. 500 °C). Lignosulfonates can be a renewable polyol component for the formulation of rigid, semi-rigid, and flexible foams.

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) was subjected to chemical extraction treatments with sodium chlorite (NaClO2) for delignification, as well as sodium hydroxide (NaOH) at various concentrations for extracting hemicelluloses gradually. Nanoindentation tests, X-Ray diffraction (XRD, and Fourier transform Raman (FT-Raman) spectroscopy studies revealed the changes in the mechanical properties and the nanostructure of the cell wall. The X-ray analysis indicated that delignification had only a moderate effect on the structure of the cell wall, while further alkali treatment led to major changes in the nanostructure. The nanoindentation tests showed that the indentation modulus and the hardness decreased after delignification and further alkali treatment, respectively. The indentation modulus of the cell wall with delignification decreased by 6.4% compared with the native cell wall, and the hardness decreased by 16.3%. After further alkali treatment, the indentation modulus and the hardness of the cell walls were 14.8% and 18.4% lower than that of the native cell walls, respectively. Additionally, the indentation modulus and the hardness of Chinese fir treated by NaOH decreased by 8.4%, and 2.1% in comparison with delignification, respectively. The results indicated that removal of hemicelluloses resulted in more damage to the mechanical properties of the cell wall compared with lignin.

The preparation and functionalization of cellulose microgels (CMGs) has been presented. Only a trace concentration of CMGs (< 0.2 wt.%) stabilized oil-in-water (O/W) emulsions and produced high internal phase emulsions (HIPE). The size and morphology of the CMGs were characterized with dynamic light scattering (DLS) and atomic force microscopy (AFM), and the structural properties were discussed. Based on the experimental results,the correlation between the amphiphilicity, and adsorption of the CMGs, and their capability to stabilize the emulsions, which are closely related to the cross-linking density of the CMGs, were elaborated. Having a porous percolating structure and being rich in free hydroxyl groups, the CMGs were functionalized by Fe3O4. The unique dispersibility of the Fe3O4-CMGs and their ability to stabilize the emulsions were investigated in detail. The results pave the way to a deeper understanding of Pickering emulsions stabilized by soft solvent-swollen materials and are expected to further expand the application of cellulose.

Sustainability and eco-efficiency are presently directing the development of the next generation of acoustic materials. In this work, foamed cellulose-polymer microsphere (PM) hybrid materials, having sound-absorbing capability, were prepared by incorporating the PMs into cellulose fibers by dehydration and foaming processes. The evolution in morphology of PMs during foaming process was investigated for different heating temperatures. The beating process disintegrated the microscopic cellulose fiber into the smaller fibers, which connected the PMs by a unique fibrous network. The influences of foaming temperature, PM content, and total areal density on the sound absorbing property of composites were studied. The results showed that incorporating the acoustic unit of elastic PMs into the porous cellulose fiber-based network significantly improved the sound absorbing ability of the composites. The sound-absorbing hybrid materials appear to be a promising alternative to non-degradable organic or inorganic acoustic composites, being economical, simple, and eco-friendly.

Fly ash-based calcium silicate (FACS), which has a large surface area (121 m2/g) and porous structure, has the potential to be used as a filler for the production of high-bulk paper. In theory, paper with a higher bulk has a lower strength. This work explores the possibility of improving paper strength without compromising its bulk through co-flocculation of cellulosic fines and FACS. To investigate the effect of co-flocculation on paper properties, composites made with various ratios of fines to FACS were studied. Results showed that paper bulk and tensile strength increased with increasing ratio of fines to FACS, up to 0.3 at 17% filler content. To further confirm these findings, the structures of composites were studied with a light microscope and scanning electronic microscope (SEM). Images showed that the composite formed at the ratio of 0.3 exhibited a larger size and looser structure than other composites, which can be attributed to the improvement of the paper’s strength and bulk. Schemes for the composite formation process and its interactions with fibers were also proposed.