Wood and Fiber Science

A experimental and comparative study on the bending strength of European Spruce and Fujian Chinese Fir

2023-09-26T15:43:17-07:00

The objective of this paper is to investigate the bending properties of European Spruce and Chinese Fir in Fujian to figure where the Chinese Fir can be used. In this paper, the bending properties of European Spruce and Chinese Fir in Fujian with different density and knots were investigated. The results showed that density and knot size have effects on the modulus of elasticity and bending strength of the two kinds of wood; the bending modulus of elasticity of European Spruce was higher than that of Fujian Chinese Fir, and the bending modulus of elasticity is higher without knot; the bending strength of European Spruce is lower than that of Fujian Chinese Fir, and the bending strength of European Spruce is lower with knots; Fujian Chinese Fir and European Spruce can be substituted each other in some low-demanding construction projects, which is helpful to improve the structural application of Fujian Chinese Fir

PHYTIC ACID FOR DUAL WOOD PROTECTION AGAINST FUNGI AND FIRE

2023-12-23T12:44:45-08:00

Phytic acid (PA) is a natural compound derived from plant seeds and cereals with excellent antifungal properties and fire resistance. However, the potential of PA for dual wood protection is yet to be reported. This study aimed to investigate the antifungal properties and fire performance of phytic acid for wood protection. The antifungal properties of PA against common wood-decaying fungi, including two white-rot fungi, Trametes versicolor (T.v.) and Irpex lacteus (I.l.), and two brown-rot fungi, Gloeophyllum trabeum (G.t.) and Rhodonia placenta (R.p.), were studied for both in vitro and in vivo tests. The thermal stability and fire resistance of wood samples treated with different concentrations of PA by vacuum impregnation were also evaluated. For the in vitro test, it was found that PA can almost fully inhibit the growth of three of the four fungi tested at PA concentration of 0.25 wt% except for fungus R.p., which was less sensitive to PA and could still grow at a PA concentration of 4 wt%. The in vivo durability test results showed that PA significantly improved the fungal resistance of both pine and poplar wood blocks, as shown by a lower mass loss of 5-25% compared to the control group's 25-45%. The results from thermogravimetric analysis (TGA) under both air and nitrogen indicated that PA increased thermal stability of both pine and poplar samples, which was further confirmed by the results from the Mass loss calorimeter (MLC). Specifically, compared to the control, the peak heat release rate and total heat release rate of 10 wt% PA-treated samples were decreased by 39% and 48% respectively, at 148 kW/m²and 34.6 MJ/m² while the residual mass increased by 137% at 48.4%. Overall, this research demonstrates the potential of using PA to improve both fungal resistance and fire performance of wood products but the leaching of PA remains.

Effects of Silica Sol Modification Impregnation on Mechanical Properties of Populus Tomentosa

2023-09-25T20:29:53-07:00

With the purpose of improving the application of fast-growing wood Populus Tomentosa, performance indicators such as the hardness of fast raw chorus, bending strength and bending resistance elasticity under different immersion conditions were studied. The fast -growing Populus Tomentosa was heated and the silica sol was immersed as immersive fluids. Orthogonal test method was used for experimental design, various performance indicators were tested and measured, and range analysis and variance analysis were used to study the correlation between process factors and properties of modified materials. The result shows that when the current vacuum time is 30min, the pre-vacuum pressure is -0.08MPa, the immersion time is 2h and the immersion pressure is 0.8MPa, the hardness of the modified material is the best. When the current vacuum time is 20min, the pre-vacuum pressure is -0.06MPa, the immersion time is 3h, and the immersion pressure is 0.8MPa, the bending elastic modulus (MOE) of the modified material is 11.44GPa, which is the highest in the experimental group. It shows that the modified material of Populus tomentosa has the best flexural performance under this condition. The end surface hardness of the modified Poplar tomentosa modified material after pretreatment and impregnation with silica sol is 5.44~6.81N, an increase of 24%~55%; the chord surface hardness is 3.90~5.42N, an increase of 29%~79%; The hardness of the radial surface is 3.89~5.04N, an increase of 31~70%, which indicates that the impregnation modification of silica sol can significantly improve the hardness of Populus tomentosa. The flexural strength of the poplar modified wood after processing was 81.1 to 11.9 MPa, which improved 23%to 70%; The flexural resistance elasticity rate was 8.92 to 11.4GPa, which improved 22%to 57%, and both flexural resistance and bending resistance elasticity were improved. The experimental result provides a reference for the application of silica sol impregnation modification in the selection of conditions.

Copper migration from treated wood garden boxes into soil and vegetable biomass Part I: The first two growing seasons after installation

2024-02-29T14:11:47-08:00

Pressure treated wood is a commonly used material for constructing garden boxes and concerns about metal leaching into garden soils and garden vegetables persists among the public. This study describes efforts to quantify copper migration from copper azole-treated garden bed frames into garden soil and vegetable biomass. Two garden bed frames were constructed from copper azole 2 x 12-inch nominal Douglas-fir lumber and two were constructed with untreated Douglas-fir lumber prior to filling with a mixture of native soil and compost. An assortment of common garden vegetables was planted in identical patterns in each of the beds for two growing seasons. During this two-year study, we found no difference in copper concentrations between identical vegetables grown in beds constructed with treated or untreated lumber. After one and two years, average copper concentrations in soil 0-25 mm from the bed frames were about 23 ppm and 21 ppm higher than soils in the same location in untreated beds, respectively (p<0.05, Tukey’s HSD). Elevated copper levels were not detected in beds constructed with treated lumber at 76-102 inches from the frames or the bed center, indicating that metal migration was limited. This study shows use of treated wood garden beds did not lead to increases in copper concentrations in vegetables grown in those beds. Treated bed materials did lose some copper to garden soil but increases in copper are limited to about 20 ppm immediately next to the treated wood frames and were not detectable at any greater distances from the wood.

Effects of different drying regimes on light hardwood tropical timber species on durability against Coptotermes curvignathus Holmgren under laboratory and field tests

2024-01-09T19:13:20-08:00

. The effects of drying temperature and duration on the durability of Lagerstroemia sp. and Cinnamomum sp. against subterranean termites; Coptotermes curvignathus were evaluated in no-choice and choice laboratory tests as well as in the above-ground test. Samples measuring 25 mm x 25 mm x 6 mm and 100 mm x 40 mm x 20 mm were dried in an oven at three different temperatures: 60 °C, 80 °C, and 100 °C for two different time periods: 10 and 15 days. In comparison between the control sample and the treated sample, the control sample showed the highest moisture content, the lowest visual rating, the lowest termite mortality, and the highest weight loss. For the treated samples, the results show that the samples for both wood species have a low resistance limit to termites at low temperatures and a short drying time. The weight loss is also high for samples with high moisture content. The mortality rate of termites was also high in samples dried at high temperatures over a long period of time compared to samples dried at low temperatures for a short period of time. The visual rating results also showed the same trend as the weight loss results. The results for these three categories are identical for the no-choice, choice and above-ground tests. The analysis demonstrates that the high material resistance of tropical wood species is mostly dependent on the temperature and length of time spent in the kiln.