Determination of formic-acid and acetic acid concentrations formed during hydrothermal treatment of birch wood and its relation to colour, strength and hardness

Sundqvist, Bror; Karlsson, Olov; Westermark, Ulla

doi:10.1007/s00226-006-0071-z

Cited by 187 publications

(116 citation statements)

References 19 publications

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“…The same initial increase was mentioned by Sundqvist et al (2006) and attributed to condensation reaction in lignin and cellulose. However this increase was not found by Korkut et al (2008) who studied heat-treated Scots pine wood and concluded that Janka hardness decreased with the increase in temperature and time of treatment.…”

Section: Janka Hardnesssupporting

confidence: 79%

Comparison between heat treated sapwood and heartwood from Pinus pinaster

et al. 2013

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Sapwood and heartwood samples of Pinus pinaster were treated in an oven at 190ºC and 200ºC for 2-6h. Dimensional stability, measured as Anti Shrinking Efficiency (ASE) between 0% and 65% relative humidity, durability against fungi, mechanical resistance (MOE and MOR), hardness and chemical composition were determined for treated and untreated sapwood and heartwood. Radial ASE reached 52% for sapwood and 50% for heartwood while tangential ASE reached 50% and 40% respectively. MOE increased slightly at the beginning of the treatment decreasing afterwards. No significant differences were found between sapwood and heartwood. MOR decreased by 50% and 30% for sapwood and heartwood respectively. A significant increase in durability against Rhodonia placenta was found for both heartwood and sapwood at the higher temperature and for heartwood only at 190º for 4h.

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Section: Janka Hardnesssupporting

confidence: 79%

Comparison between heat treated sapwood and heartwood from Pinus pinaster

et al. 2013

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“…Increases in modulus of elasticity and rupture have been widely reported in the literature, especially increasing material density (kamke, 2006;sundqvist et al, 2006;Gáborík et al, 2011). Hillis (1984) and Yildiz et al (2006) observed that by using only thermal treatments, without compression influence, modulus of rupture is usually more affected than the modulus of elasticity.…”

Section: Discussionmentioning

confidence: 97%

EFFECT OF THERMO-MECHANICAL TREATMENT ON PROPERTIES OF PARICA PLYWOODS (Schizolobium amazonicum Huber ex Ducke)

Costa

Menezzi

2017

Rev. Árvore

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-Thermo-mechanical treatment is a technique for wood modification in which samples are densified by means of heat and mechanical compression, applied perpendicularly to fibers, which under different combinations of time, temperature, and pressure increases wood density and thus improve some of its properties. This study aimed to treat thermo-mechanically parica plywood and observe the effects on its physical and mechanical properties. Specimens were submitted to two treatments, 120 and 150 °C, remaining under pressure for seven minutes and, subsequently, under zero pressure for 15 minutes. Results showed a significant increase in specific mass from 0.48 g cm -3 to an average of 0.56 g cm -3 , and a compression ratio of about 31.7% on average. Physical properties also varied significantly and results showed that treated samples swelled and absorbed more water than those untreated, leading to a greater thickness non-return rate. This indicates the proposed thermal treatments did not release the internal compressive stress generated during panel pressing, not improving its dimensional stability as a result. On the other hand, mechanical properties were positively affected, leading to an increase of 27.5% and 51.8% in modulus of rupture after treatments at 120 and 150 °C, respectively. Modulus of elasticity and glue-line shear strength did not vary statistically and Janka hardness was 29.7% higher after treatment at 150 °C.Keywords: Thermo modification; Wood panels; Densification EFEITO DO TRATAMENTO TERMO-MECÂNICO SOBRE AS PROPRIEDADES DE COMPENSADOS DE PARICÁ (Schizolobium amazonicum Huber ex Ducke)RESUMO -O tratamento termomecânico é uma metodologia para modificação da madeira, onde as amostras são densificadas por meio do calor e da compressão mecânica aplicada perpendicularmente às fibras, que submetidas a diversas combinações de tempo, temperatura e pressão aumentam a densidade da madeira e assim melhoram algumas de suas propriedades. O presente trabalho teve como objetivo tratar termomecanicamente compensados de paricá e observar os efeitos nas suas propriedades físicas e mecânicas. Os corpos-de-prova foram submetidos a dois tratamentos: a 120°C e a 150°C, mantidos sob pressão por sete minutos e, posteriormente, sob pressão zero, por quinze minutos. Os resultados mostraram que houve aumento significativo da massa específica de 0,48g/cm 3 para, em média, 0,56 g/cm 3 , e a taxa de compressão foi de 31,7% em média. As propriedades físicas também variaram significativamente, e os resultados mostraram que as amostras tratadas incharam e absorveram mais água que as testemunhas, levando a uma maior TNRE (taxa de não-retorno em espessura). Isto indica que os tratamentos térmicos propostos não liberaram as tensões internas de compressão geradas durante a prensagem do painel, não melhorando sua estabilidade dimensional. As propriedades mecânicas, por sua vez, foram afetadas positivamente, levando a um aumento de 27,5% e 51,8% do MOR após os tratamentos a 120°C e a 150°C, respectivamente. O MOE e o cisalhamento...

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“…The loss of strength is associated with changes in wood acidity (Hodgin and Lee 2002). Sundqvist et al (2006) found that when birch was heated to 180 °C for 1 to 2.5 h, it lost considerable strength and hardness. Losses in mechanical properties can be linked to the loss of mass and increase in concentrations of formic and acetic acid.…”

Section: Introductionmentioning

confidence: 99%

Effects of Boron Impregnation and Heat Treatment on Some Mechanical Properties of Oak (Quercus petraea Liebl.) Wood

Perçin¹,

Sofuoğlu²,

Uzun³

2015

BioResources

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Heat treatment changes some physical, mechanical, and chemical properties of wood. Inorganic borates have been used as wood preservatives for many years. The aim of this study was to investigate the effects of impregnation chemicals on some mechanical properties (bending strength (MOR), modulus of elasticity (MOE), tensile strength parallel to the grain (TS), compression strength parallel to the grain (CS), and shear strength parallel to the grain (SS)) of heat-treated oak (Quercus petraea Liebl.). For this purpose, the oak wood specimens were impregnated with 5% aqueous solution of boric acid (BA) and borax (BX). Then specimens were heat-treated at 160, 190, and 220 °C for 2 and 4 h. According to the results of the study, borax retention value was higher than boric acid. The bending strength, modulus of elasticity in bending, tensile strength parallel to the grain, and shear strength parallel to the grain decreased due to heat treatment. The highest mechanical strength losses were determined in samples heat treated at 220 °C for 4 h. Generally the mechanical strength losses of samples impregnated with borax were lower than non-impregnated controls and specimens impregnated with boric acid.

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Determination of formic-acid and acetic acid concentrations formed during hydrothermal treatment of birch wood and its relation to colour, strength and hardness

Cited by 187 publications

References 19 publications

Comparison between heat treated sapwood and heartwood from Pinus pinaster

Comparison between heat treated sapwood and heartwood from Pinus pinaster

EFFECT OF THERMO-MECHANICAL TREATMENT ON PROPERTIES OF PARICA PLYWOODS (Schizolobium amazonicum Huber ex Ducke)

Effects of Boron Impregnation and Heat Treatment on Some Mechanical Properties of Oak (Quercus petraea Liebl.) Wood

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