Evaluation of thermally modified beech and spruce wood and their properties by FT-NIR spectroscopy

This study was aimed at evaluating the effect of thermal modification temperature on the mechanical properties, dimensional stability, and biological durability of Picea mariana. The boards were thermally modified at different temperatures 190, 200 and 210°C. The results indicated that the thermal modification of wood caused a significant decrease in the modulus of rupture (MOR) after 190°C, while the modulus of elasticity (MOE) seemed less affected with a slight increase up to 200°C and slight decrease with further increase in temperature. The hardness of the thermally modified wood increased in the axial direction. This increase was also observed in tangential and axial directions but at a lesser extent. The final value was slightly higher in axial direction and lower in radial and tangential directions compared to those of the untreated wood. Dimensional stability improved with thermal modification in the three directions compared to the dimensional stability of unmodified wood. The fungal degradation results showed that the decay resistance of thermally modified wood against the wood-rotting fungi Trametes versicolor and Gloephyllum trabeum improved compared to that of the untreated wood. By contrast, the thermal modification of P. mariana had a limited effect on the degradation caused by the fungus Poria placenta.

Section: Introductionmentioning

confidence: 99%

Effect of thermal modification temperature on the mechanical properties, dimensional stability, and biological durability of black spruce (Picea mariana)

Lekounougou

Kocaefe

2014

“…Similar observations were made with the decreased absorption of main region peaks that were located at around 1250 nm; 1620 nm; 1820 nm and 2200 nm. These regions corresponded to the overtones and combination of fundamental vibrational transitions in the infrared region, mainly C-H (hydrocarbons …), C=O (cellulose, hemicelluloses…); O-H (water, alcohol, cellulose…), N-H (lignin, hemicelluloses…) functional groups, respectively (Thygesen and Lundqvist 2000a, 2000b, Cozzolino et al 2003, González-Martían et al 2003, Bachle et al 2010, Schwanninger et al 2004. Thus, the decreased reflectance presented in Figure 2 can be attributable to the degradation of the cell wall polymers.…”

Section: Discussionmentioning

confidence: 79%

“…Increasing contact angles with the exposure time ( Figure 4) are due to increased hydrophobicity as well as due to the acid nature of the wood surface (Good and Kotsidas 1979, Chen et al 1995, Gaintantzopoulou et al 2009, Bachle et al 2010, Vázquez et al 2011. In particular, the effect of exposure to high temperatures of veneer surfaces may cause a decrease in hydroxyl bonding potential.…”

Section: Discussionmentioning

confidence: 95%

“…It has long been recognised that high temperature leads to a partial degradation of cell wall material that will have an effect on wood chemical composition and mechanical properties (Bachle et al 2010, Sanchez-Zapata et al 2011. Surface quality sensing of trembling aspen veneer products 21 chemical wood polymers' degradation at high temperatures (specifically a reduction in hemicelluloses).…”

Section: Discussionmentioning

confidence: 99%

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Surface quality sensing of trembling aspen (Populus tremuloidesMichx.) veneer products by near infrared spectroscopy

Koumbi-Mounanga

Ung

Cooper

et al. 2014

The potential of near infrared spectroscopy (NIRS) to estimate wood moisture content (MC), surface energy characteristics and adhesive bond strength were evaluated on aspen (Populus tremuloides Michx.) veneer subjected to different drying times. For samples dried progressively at 103°C, the best MC prediction model was for the total MC range (0-100%) with an R 2 value of 0.68. However, exposure at 180°C produced surface colour changes, and the CIE L*a*b* colour parameters measuring colour changes were better estimated using the 400-900 nm spectral data than the 1100-2400 nm spectral data. Increased exposure time at 180°C resulted in lower wettability and, hence, larger contact angles, especially when ethylene glycol was used as probe solvent. Lap shear strength tests on veneers showed that adhesion by phenol formaldehyde resins was impaired by the high temperature exposure; however, the lap shear strength test had high variability so there was not always a clear relationship between contact angle and lap shear strength test.

“…In a preliminary study, Taylor and Via (2009) investigated the utility of visible and NIR spectroscopy in predicting the phenol-formaldehyde adhesive content of oriented strandboard postmanufacture. Bachle et al (2010) used the technique to assess the quality of thermally modified spruce [P. abies (L.) Karst.] and beech (Fagus sylvatica L.) wood.…”

Section: Introductionmentioning

confidence: 99%

Near-infrared spectroscopy for the quantification of linseed oil uptake in Scots pine (Pinus sylvestrisL.)

Eriksson

Geladi

Ulvcrona

2011

Eighteen sapwood and 18 heartwood samples from three Scots pine (Pinus sylvestris L.) trees were used to identify correlations between the features of their near-infrared spectra (400-2500 nm) measured before and after impregnation with linseed oil (Linogard † ) and (1) the amount of oil taken up by the samples at three different longitudinal positions; and (2) the tissue type of sample. Calibration models were cross-validated and oil uptake models were also validated on separate test sets. Partial least squares regression models for the prediction of uptake and tissue type in non-impregnated wood were promisingly accurate, having coefficients of multiple determination (Q 2 ) values of ! 0.8, 0.8 and 0.75 for predictions of tissue type, oil taken up as a percentage of sample mass and total mass of oil taken up, respectively. The models developed for linseed oil-impregnated samples were better still, generating Q 2 values of ! 0.9, ! 0.8 and 0.8 for the three key properties. In general, models based on spectra acquired along two directions of measurement (longitudinal and tangential) were more accurate than models based on only one. Tandem models consisting of two submodels, one for sapwood and one for heartwood, were more successful than single models applicable to both tissue types.