Volume 9 Issue 4

The morphology and thermo-mechanical properties of recycled polystyrene-based materials (rPS) reinforced with 5 and 15% lignin from kraft pulping of Eucalyptus nitens were studied. The lignin was modified through two esterification processes using either acetic or maleic anhydride, and changes in the structure of the esterified lignin functional groups were analyzed by Fourier transform infrared spectroscopy. The lignin was then incorporated into rPS by melt mixing. Torque variation in the process was evaluated, and the values were compared to those of neat rPS and virgin PS. The results show a plasticizing effect of lignin with a reduction in the torque values. The morphology, studied through scanning electron microscopy, shows a particle size reduction of acetylated and maleated lignin and a more homogeneous dispersion at 5%. The thermal behavior of the composites, studied through differential scanning calorimetry, does not show significant changes in the glass-transition temperature of rPS with the presence of lignin. The dynamic mechanical analysis shows an increasing storage modulus with increasing lignin content. Thermal stability, studied through thermogravimetric analysis, improved for composites containing 5% esterified lignin. The flexural modulus also increased with lignin addition. These results suggest that the thermal and mechanical properties of post-consumer recycled polystyrene can be significantly improved with only 5% esterified lignin.

The objective of this study was to better understand changes in the hardwood lumber supply chain from the perspective of lumber producers and distributors and to assess the degree of judgmental convergence between suppliers and buyers of hardwood lumber. Results from two nationwide surveys conducted in 2008 and 2009 were used for the analysis. Findings confirmed a decline in demand for red oak and an increase in species diversity in the market, although a majority of sales were dominated by five species. Results also showed an increasing importance of markets for lower grades of lumber, such as pallets, containers, and railroad ties, and a decline in demand for higher-value products such as furniture and kitchen cabinets. The importance of the lumber distributor role in the hardwood supply chain also has increased. Both sawmills and suppliers have increased their offerings of customized products and services in response to market demand. The customer base is changing, with smaller, more customized orders being sold to smaller businesses. Some of the trends and changes identified are structural and long-running in nature and are not expected to change in the short term.

The conversion of lignin into value-added products is traditionally hampered by its stochastic structure and its complex reactivity. The allylation reaction and the aromatic Claisen rearrangement of the allyl group on lignin as chemical modifications are reported for the first time in this work. This approach is aimed at the development of new lignin-based materials and the improvement of its compatibility and ease of processing. In particular, the Claisen rearrangement of lignin is foreseen as a valuable approach to release phenolic groups in an already chemically modified lignin, giving additional reactive sites for further transformation. These reactions were carried out on a purely guaiacylic lignin (TMP), taken as reference material due to its simplicity, and on a more structurally complex herbaceous lignin (P1000®). The Claisen rearrangement of the allylic chain was successfully achieved by treatment in dimethylformamide at reflux temperature for 15 hours. Finally, a screening of the antioxidant activity of reference, allylated, and Claisen rearranged lignins was carried out. Rearranged lignins exhibited satisfactory antioxidant activities if compared to the reference ones.

Processing Australian hardwood plantations into rotary veneer can produce more acceptable marketable product recoveries compared to traditional processing techniques (e.g. sawmilling). Veneers resulting from processing trials from six commercially important Australian hardwood species were dominated by D-grade veneer. Defects such as encased knots, gum pockets, gum veins, surface roughness, splits, bark pockets, and decay impacted the final assigned grade. Four grading scenarios were adopted. The first included a change to the grade limitations for gum pockets and gum veins, while the second investigated the potential impact of effective pruning on grade recovery. Although both scenarios individually had a positive impact on achieving higher face grade veneer qualities, the third and fourth scenarios, which combined both, had a substantial impact, with relative veneer values increasing up to 18.2% using conservative calculations (scenario three) or up to 22.6% (scenario four) where some of the upgraded veneers were further upgraded to A-grade, which attracts superior value. The total change in veneer value was found to depend on the average billet diameter unless defects other than those relating to the scenarios (gum or knots) restricted the benefit of pruning and gum upgrading. This was the case for species prone to high levels of growth stress and related defects.

Three layers of wood-based composites of planed lumber-UHMWPE-veneer structure were prepared using polyurethane (PUR) as the resin matrix. The effects of ultrahigh molecular weight polyethylene (UHMWPE) fiber on the wood’s bending performance, tensile properties, and other mechanical properties, such as shear resistance to the agglutination interface, were investigated. Chemical constituents of debonded fibers were characterized by infrared spectroscopy (FTIR). The results show that PUR could feasibly be used to manufacture UHMWPE fiber/wood composites. UHMWPE fiber played an important role in the wood destruction process and improved the flexural performance of the lumber. This positive effect was closely related to the thickness of veneer. When fiber was within the load-bearing strength range, there was a positive correlation between the tensile strength and the bonding distance. Meanwhile, the reinforcing effect of UHMWPE fiber strongly affects the performance of the bonding interface under shear.

Agatis wood (Agathis lorantifolia Salisb.) was impregnated with a combination of styrene and methyl methacrylate and compressed to a strain of 50% to improve dimensional stability and termite resistance. The changes in cell structure were analyzed to determine the effects of the combination treatment. The results showed that densification of agatis wood with compression, impregnation, and a combination of treatments resulted in an increase in physical properties (density and dimensional stability) by changing the cellular structure and chemical components (i.e., cellulose crystallinity, microfibril angle, and preferred orientation of fibers) as well as degradation of cellulose. The chemical modification and combination treatment (chemical and compression) of wood generally led to a high resistance to dry wood termites.

There is increasing competition for raw materials between particleboard production, thermal energy recovery, and pulp- and papermaking. According to different scenarios, the consumption of lignocellulosic raw materials is increasing, which means that the competition is increasing. The primary production of lignocellulosic raw material in some regions may therefore reach the limit of sustainability; i.e., the lignocellulosic raw material must be used more efficiently to reduce the risk of a shortage. The physical and chemical properties of the lignocellulosic raw material of selected species have therefore been surveyed, and the raw material properties that are important for each of the three competitors have been defined. The aim of the study is to characterise the lignocellulosic raw materials according to the three competing users and to show whether they are high or low in competition. As methods, a relative ranking of the species regarding their raw material properties and regarding the requirements of the competitors as well as cluster analysis were chosen. The results show that the most favourable raw materials are from coniferous species, while monocotyledon species show an opposite trend.

Biochar (BC) is a carbonaceous and porous product generated from the incomplete combustion of biomass and has been recognized as an efficient adsorbent. This study evaluated the ability of BC to sorb atrazine pesticide in tropical soil, and explored potential environmental values of BC on mitigating organic micro-pollutants. BC was produced from cassava waste via pyrolyzation under oxygen-limiting conditions at 350, 550, and 750 °C (MS350, MS550, and MS750, respectively). Three biochars were characterized and investigated as sorbents for the removal atrazine from tropical soil. BC pyrolyzed at higher temperatures more quickly reached equilibrium. The pseudo-second-order model perfectly simulated the sorption kinetics for atrazine with the coefficients R2 above 0.996, and the sorption amount at equilibrium (qe) was 0.016 mg/g for MS350, 0.025 mg/g for MS550 and 0.050 mg/g for MS750. The isotherms of MS350 displayed relatively linear behavior, whereas the sorption of atrazine on MS550 and MS750 followed a nonlinear isotherm. The sorption data were well described by the Freundlich model with logKF of 0.476 for MS350, 0.771 for MS550, 1.865 for MS750. A thermodynamic study indicated that the sorption of atrazine in BC-added soil was a spontaneous and endothermic process and was primarily controlled by physisorption. In addition, lower pH was conducive to the sorption of atrazine in BC-added soil.

Dry thermal treatments of wood samples were carried out at 160 and 200 °C. After each treatment, the samples were irradiated using a strong UV emitter mercury lamp, and the colour change was then evaluated. For control, untreated samples were also irradiated using the same mercury lamp. Results showed that the extractive content of the wood played an important role in the colour change not only during thermal treatment but also during light irradiation. It was found that, compared to the thermally untreated samples, the thermal treatment at 200 °C reduced the red colour change due to photodegradation. The yellow colour change of photodegradation was hardly affected by the applied thermal treatments, showing that thermal treatments were not able to reduce the light degradation of lignin. The applied treatments slightly stabilized the wood against the degrading effect of light. The wood treated at lower temperature (160 °C) had less colour change induced by the light source.

Residential construction consumes an estimated 26 percent of the total U.S. wood harvest and thus plays an important role in the forest products value chain. While being a relatively small part of the U.S. residential construction market, the factory-built residential housing industry, originating from manufactured homes (e.g. mobile homes), is embracing emerging industry segments such as modular or panelized homes. Since indications exist that factory-built home production is slated to gain a more prominent role in the U.S. construction markets at the cost of traditional stick-built production, the factory-built home industry sub-segment is of considerable importance to the forest products industry. This research looks at manufactured home producers as a benchmark for analyzing the current economic state of the industry and discusses competitive strategies. The analysis concludes, through macroeconomic modeling, that manufactured homes are in the declining stage of their product life cycle due to changes to the U.S. residential construction sector and the factory-built home industry and by advancements of rival industry-segments. As market share continues to decline, firms operating in this industry-segment seek to either hedge their losses through product diversification strategies or remain focused on strategically repositioning the manufactured home segment.