Heat-Induced Chemical and Color Changes of Extractive-Free Black Locust (Robinia Pseudoacacia) Wood

Chen, Yao; Gao, Jianmin; Fan, Yongming; Tshabalala, Mandla A.; Stark, Nicole M.

doi:10.15376/biores.7.2.2236-2248

Cited by 79 publications

(99 citation statements)

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“…High values of a* are related to condensation, decomposition and/or oxidation of proanthocyanidins, lignin and other extractives in byproducts. These byproducts absorb complementary red light, contributing to the increment of red tones in wood (Chen et al 2012). In this study, significant decrease of a* can be attributed to changes in lignin structure, since red tones of wood surface decreased and absorption in 400 cm -1 (related to lignin) also decreased after outdoor exposure ( Figure 2B, 2C and 2D).…”

Section: Resultsmentioning

confidence: 49%

Natural weathering performance of three fast-growing Eucalypt woods

Cademartori

Missio

Mattos

et al. 2015

Maderas, Cienc. tecnol.

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We investigated the effect of outdoor exposure on the wood surface from three fast-growing Brazilian eucalypts through color, wetting and thermal analyzes. Gympie messmate (Eucalyptus cloeziana), rose gum (Eucalyptus grandis) and blue gum (Eucalyptus saligna) woods were exposed outdoors in a subtropical region for 360 days. We performed three collections every 120 days. We investigated color changes of untreated and weathered woods through a spectrophotometer (CIEL*a*b* system) and changes in macro compounds of wood through thermogravimetric analysis. In addition, the apparent contact angle and work of adhesion were evaluated using a goniometer. Outdoor exposure for 120 days provided significant increment in grayish of wood surface. Thermogravimetric curves of wood changed after the weathering, especially in the regions related to hemicelluloses and lignin thermal degradation. Outdoor exposure for 360 days converted hydrophilic wood surface into a very hydrophilic one, wherein occurrence of microcracks contributed to fully spreading of water droplets.

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Section: Resultsmentioning

confidence: 49%

Natural weathering performance of three fast-growing Eucalypt woods

Cademartori

Missio

Mattos

et al. 2015

Maderas, Cienc. tecnol.

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“…The intensity of the aromatic skeletal vibration increment located at 1602 cm -1 after heat-treatment could be caused by cleavage of the propyl groups in lignin (Ucar et al 2005). The intensified peak at 1454 cm -1 denoted the formation of new conjugated double bounds due to the heat treatment (Chen et al 2012). The carbonyl absorption peak at 1720 cm -1 to 1740 cm -1 decreased after the heat treatment.…”

Section: Ftir Spectroscopy Analysismentioning

confidence: 99%

Technological and Thermal Properties of Thermoplastic Composites Filled with Heat-treated Alder Wood

et al. 2016

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This study investigated the effect of heat-treated wood content on the water absorption, mechanical, and thermal properties of wood plastic composites (WPCs). The WPCs were produced from various loadings (30, 40, and 50 wt%) of heat-treated and untreated alder wood flours (Alnus glutinosa L.) using high-density polyethylene (HDPE) with 3 wt% maleated polyethylene (MAPE) coupling agent. All WPC formulations were compression molded into a hot press for 3 min at 170 ºC. The WPCs were evaluated using mechanical testing, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The mechanical property values of the WPC specimens decreased with increasing amounts of the heattreated wood flour, except for the tensile modulus values. The heat treatment of alder wood slightly increased the thermal stability of the WPCs compared with the reference WPCs. The crystallization degree (Xc) and the enthalpy of crystallization of the WPCs slightly decreased with increasing content of the heat-treated wood flour. However, all WPCs containing the heat-treated alder wood flour showed a higher crystallinity degree than that of the virgin HDPE.

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“…The chemical changes leading to thermally induced color changes in wood are complex and not yet completely understood, but they are related to degradation products of hemicelluloses, lignin, and certain extractives (Fengel and Wegener 1984;Sandquist 2004;Chen et al 2012Chen et al , 2014.…”

Section: Monitoring Ageing By Color Measurementsmentioning

confidence: 99%

“…These changes can be associated with the thermal degradation of hemicelluloses, which are more sensitive to temperature. In fact, temperature-induced color changes are mostly related to chromophores resulting from hydrolytic and oxidative processes of hemicelluloses, though lignin and extractives may contribute to some extent (Chen et al 2012(Chen et al , 2014. Table 2 shows the ratios of the integrated areas of some relevant absorption bands, as relative values are reported to the corresponding values of the control samples.…”

Section: Ftir Investigation Of Surface Chemical Changesmentioning

confidence: 99%

Effects of Ageing on the Color and Surface Chemistry of Paulownia Wood (P. elongata) from Fast Growing Crops

Liu¹,

Timar²,

Varodi³

et al. 2016

BioResources

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The behavior of paulownia wood (Paulownia elongata) was investigated using three different ageing tests: simulated natural ageing under the influence of light under indoor conditions, temperature-induced ageing in the dark, and UV-induced ageing. Ageing effects were evaluated by color measurements in the CIE Lab system. Simulated natural ageing of wood in indoor conditions (6 months) and UV-accelerated ageing (72 h) are complex and dynamic processes, which resulted mostly in yellowing of the samples due to photo-degradation. Temperature-induced ageing (288 h at 100 C) resulted mostly in a rapid and visible darkening of the paulownia wood. Comparative in-time evolution of color changes during accelerated UV ageing testing and simulated natural ageing testing under indoor conditions allowed the estimation of an acceleration index of about 50X. Fourier transform infrared spectroscopy (FTIR) was used to examine specific chemistry changes occurring during these ageing tests. UV light from natural or artificial sources caused primarily lignin degradation followed by oxidative processes leading to carbonylcontaining chromophores. Temperature-induced partial degradation of hemicelluloses and oxidative processes resulted in the formation of chromophores containing mostly conjugated carbonyl groups. This research highlighted that paulownia wood (P. elongata) is quite sensitive to ageing under the action of light and temperature, which cause notable color and surface chemistry changes.

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Heat-Induced Chemical and Color Changes of Extractive-Free Black Locust (Robinia Pseudoacacia) Wood

Cited by 79 publications

References 0 publications

Natural weathering performance of three fast-growing Eucalypt woods

Natural weathering performance of three fast-growing Eucalypt woods

Technological and Thermal Properties of Thermoplastic Composites Filled with Heat-treated Alder Wood

Effects of Ageing on the Color and Surface Chemistry of Paulownia Wood (P. elongata) from Fast Growing Crops

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