Combined analysis of microstructures within an annual ring of Douglas fir (Pseudotsuga menziesii) by dynamic mechanical analysis and small angle X-ray scattering

Dynamic mechanical analysis (DMA) and small angle X-ray scattering (SAXS) measurements of water-saturated wood of Douglas fir (Pseudotsuga menziesii) in the temperature range of 0 ℃ to 100 ℃ were focused to clarify microstructural changes within an annual ring. The following results were obtained. Thermal softening behavior caused by micro-Brownian motion of lignin was observed in both earlywood and latewood. The peaks of tanδ were found at around 95 ℃ for earlywood and at around 90 ℃ for latewood. These results suggested that the structures of lignin in the cell wall were different between earlywood and latewood. SAXS measurements of water-saturated earlywood and latewood in water were performed with precise temperature control. The scattering intensity increased with increasing temperature, indicating that the density of the matrix was reduced at higher temperature. One-dimensional SAXS intensity at the equator, which approximately represents cellulose microfibrils arrangement in the matrix, was intensively analyzed using the WoodSAS model. The result of this model fitting showed that the cellulose microfibril diameter of latewood was higher than that of earlywood. In addition, the value of interfibrillar distance decreased monotonically in the earlywood, while it decreased rapidly in the latewood from 60 ℃ to 90 ℃. The changes in the cellulose microfibril (CMF) diameter and the interfibrillar distance with increasing temperature between earlywood and latewood by SAXS measurement were different. The differences in CMF diameter and inter-fibril distance between earlywood and latewood measured by SAXS also support the hypothesis that lignin structure differs between earlywood and latewood based on the results of DMA measurements

Transition in viscoelastic properties within successive annual rings of radiata pine (Pinus radiata)

Abstract Dynamic mechanical analysis (DMA) measurements of water-saturated radiata pine wood in the temperature range from 0 ℃ to 100 ℃ were focused to clarify the transition in viscoelastic properties within successive annual rings. Four radially consecutive specimens were taken per annual ring and DMA measurements in the tangential direction were performed using these specimens. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in all samples. The temperature of peak tanδ tended to decrease from earlywood to latewood within an annual ring. The temperature of peak tanδ increased across annual ring boundary. The same trend was repeated within the next annual ring. It was found that the viscoelastic properties transitioned within successive annual rings

Quantification of Greenhouse Gas Emissions from Wood-Plastic Recycled Composite (WPRC) and Verification of the Effect of Reducing Emissions through Multiple Recycling

Wood-plastic recycled composite (WPRC) is a building material that uses certain amounts of recycled wood and/or plastic materials contained in wood-plastic composites. They are characterized by multiple recycling processes in which products that become post-consumer materials are technically able to be recycled to produce WPRC products. However, there is no research case that quantifies the effect of reducing greenhouse gas (GHG) emissions for the feature of multiple recycling. In this study, we quantified GHG emissions during the life cycle of WPRC that was manufactured by companies certified to the Japanese Industrial Standard (JIS) A 5741, using the life cycle assessment method. The following conclusions were revealed in this study. (1) The GHG emission of the targeted WPRC was 3489 kg-CO2e/t, and the emission rates from the WPRC production process and the combustion of WPRC waste were found to be particularly high. (2) It was found that setting the recycled material rate of plastic materials to 100% would reduce GHG emissions by 28% (1316 kg-CO2e/t) compared to when the recycled material rate was 0%. (3) It was also found that GHG emissions can be reduced by up to about 28% by multiple recycling of WPRC. It can be said that this study set a benchmark of GHG emissions for WPRC produced in Japan