Volume 8 Issue 1

This paper considers the modification of wood-derived cellulose assisted by supercritical carbon dioxide (SC-CO2). Cellulose carbamate derivatives were successfully prepared from softwood pulp at 150 °C and 3000 psi for 6 hours. Compared with conventional methods, SC-CO2 was shown to be more efficient in the modification of wood-derived cellulose. The modified cellulose had a considerable increase in nitrogen content. During the characterization Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetry (TG), and Field Emission Scanning Electron Microscopy (FE-SEM) were employed to investigate the structural and morphological changes in modified cellulose from wood.

The performance of veneer joints is known to affect the quality of laminated veneer lumber (LVL), so experimental research and simulation analysis of the tensile properties of lap joints were performed and reported in this paper. The lap length, specimen thickness, and specimen width were selected as the experimental factors. The maximum tensile load increased with the increase of each factor; the tensile strength increased with the increase of lap length, whereas it decreased with the increase of specimen thickness. Specimen width had significant effect on the maximum tensile load, but had little influence on the tensile strength. A response surface model of tensile strength was obtained using Matlab software, and it was used to predict the tensile properties for lap joints. The results of ANSYS simulation analysis showed that the stress peaks were concentrated in the joint ends; the peak shear stress and peak stripping stress all decreased with the increase of lap length and increased with the increase of specimen thickness; the result was consistent with the experimental results; therefore, the finite element simulation results can be used for the optimized selection of size parameters of joints.

A Plackett-Burman design was used to pre-optimize the medium composition for biobutanol production using a unique isolate of solvent-producing Clostridium YM1. Various nutrient factors affecting biobutanol production were screened using the Plackett-Burman design. These factors included: glucose, tryptone, yeast extract, peptone, ammonium acetate, KH2PO4, K2HPO4, MgSO4, FeSO4, Na2CO3, and NaCl. The results were analyzed by an analysis of variance (ANOVA), which showed that glucose, tryptone, yeast extract, peptone, K2HPO4, Na2CO3, and MgSO4 had significant effects on biobutanol production. However, ammonium acetate, KH2PO4, and FeSO4 had insignificant effects. The established model from the ANOVA analysis had a significant value of Pmodel > F = 0.0245 and an R2 value of 0.999. The estimated maximum biobutanol production was 9.01 g/L, whereas the optimized medium produced 10.93 g/L of biobutanol.

In the production of paper, especially when using mechanical pulp or recovered wood-containing paper, a large amount of dissolved and colloidal substances (DCS), mainly composed of hemicelluloses, extractives, lignans, and lignin-related substances, are released from the pulp and dissolved or dispersed into the process water. The accumulation of DCS during the papermaking operations due to the closure of process water systems gives rise to various detrimental impacts on the papermaking process and the resulting paper products. Thus it is indispensible to remove or control the DCS in order to overcome or alleviate their negative influences. This review emphasizes recent advances in control of DCS by physical, chemical, and biological methods. The widely used fixatives such as aluminum sulfate, poly-(aluminum chloride), polyamines, polyvinyl amine, and highly cationic starch, as well as their functional effectiveness, mechanism, influencing factors, and influences on paper products are considered. Simultaneously, biological treatments including fungal treatment and enzymatic treatments with lipase, pectinase, laccase, and immobilized enzymes, are also assessed in detail. DCS control has been an important way to improve the runnability of paper machines and the quality of wood-containing paper and recycled paper products. Advances in DCS control are likely to create additional benefits to the papermaking industry in the coming years.

The cleavage of lignin bonds in a wood matrix is an important step in the processes employed in both the biorefinery and pulp and paper industries. β-O-4 ether linkages are susceptible to both acidic and alkaline hydrolysis. The cleavage of α-ether linkages rapidly occurs under mildly acidic reaction conditions, resulting in lower molecular weight lignin fragments. Acidic reactions are typically employed in the biorefinery industries, while alkaline reactions are more typically employed in the pulp and paper industries, especially in the kraft pulping process. By better understanding lignin reactions and reaction conditions, it may be possible to improve silvicultural and breeding programs to enhance the formation of easily removable lignin, as opposed to more chemically resistant lignin structures. In hardwood species, the S/G ratio has been successfully correlated to the amount of β-O-4 ether linkages present in the lignin and the ease of pulping reactions.

UV weathering, a process initiated primarily by the ultraviolet portion of the solar spectrum, causes surface degradation of wood. Additionally, the wetting and drying of wood through precipitation, diurnal and seasonal changes in relative humidity, abrasion by air particulates, temperature changes, atmospheric pollution, oxygen, and human activities, all contribute to the degradation of wood surfaces. Photo-oxidation or photo-chemical degradation affects only the wood surface, starting immediately after exposure to sunlight. Understanding the chemistry of UV degradation of wood requires knowledge of the chemical nature of wood components, the UV spectrum, and the interactions of UV radiation with various chemical structures in wood. Chemical changes can be evidenced by FTIR spectroscopy. Previous study has shown that wood chemical modification with succinic anhydride makes it slightly more stable to the artificial light action than non-modified wood, which might be due to a slight increase in lignin stability to the polychromatic light action. Analysis of color changes on coated wood surfaces for modified wood treated with epoxidized soybean oil (ESO) has shown that lightness (ΔL*) decreases, whereas a*, b*, and ΔE* increase with increasing irradiation time.