Evaluation of the thermal stability and set recovery of thermo-hydro-mechanically treated lime (Tilia cordata) wood

Popescu, Maria-Cristina; Lisă, Gabriela; Froidevaux, Julien; Navi, Parviz; Popescu, Constantin

doi:10.1007/s00226-013-0588-x

Cited by 29 publications

(24 citation statements)

References 18 publications

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“…It is also suitable for veneer and produces a high quality charcoal. Tilia wood also reacts very well to THM (thermo-hydro-mechanical process) densification treatment [105]. This process significantly improves its dimensional stability, but reduces its thermal stability.…”

Section: Basic Wood Properties and Usementioning

confidence: 99%

A Review of the Characteristics of Small-Leaved Lime (Tilia cordata Mill.) and Their Implications for Silviculture in a Changing Climate

Jaegere

Hein

Claessens

2016

Forests

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Tilia cordata Mill. is a minor European broadleaved species with a wide but scattered distribution. Given its scarcity and low value in the wood market, it has received little attention from researchers and forest managers. This review summarizes the main aspects of T. cordata ecology and growth. Its main limiting factor is its need for warm summer temperatures to ensure successful seed production. It has a height growth pattern relatively similar to that of Acer pseudoplatanus L., with a slight delay in the early stages. Yield tables report great productivity, especially in eastern Europe. T. cordata used to be a major species in Europe, in contrast to its present distribution, but it is very likely to receive renewed interest in the future. Indeed, with the potential change of competition between species in some regions and the need for important diversification in others, T. cordata may play an important role in forest adaptation to climate change, especially owing to its wide ecological tolerance and its numerous ecosystem services. It is necessary to increase our knowledge about its regeneration and its responses to environmental and silvicultural factors, to establish clear management recommendations.

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Section: Basic Wood Properties and Usementioning

confidence: 99%

A Review of the Characteristics of Small-Leaved Lime (Tilia cordata Mill.) and Their Implications for Silviculture in a Changing Climate

Jaegere

Hein

Claessens

2016

Forests

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“…Applying such a solution is unjustified if the main goal of densification is to obtain materials with a high wood surface hardness, for example flooring materials or wall strips. It should be noted that the main problem involved in thermo-mechanical treatment of wood is a tendency for dimensions to change after the modification, most frequently referred to as "set-recovery" (Fang et al 2012;Popescu et al 2014;Laine et al 2016). Kutnar et al (2009) stated that wood with the highest degree of compression shows the highest potential for compression strain recovery.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Process Parameters on the Density Profile and Hardness of Surface-densified Birch Wood (Betula pendula Roth)

Laskowska¹

2017

BioResources

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This study examined the influence of temperature and time of treatment on the density profile and hardness of surface-densified birch wood (Betula pendula Roth). An analysis of the wood density profile was conducted on the basis of the following parameters: thickness, maximum density, and the distance between the maximum density and the wood surface. Depending on the technological parameters' values, the degree of compression of the wood was 13% to 22%, and its maximum density was 808 kg/m 3 to 994 kg/m 3 . As a result of the modification of birch wood at a temperature of 100 °C and 125 °C, the wood was densified on one side. As the temperature of the thermo-mechanical treatment was raised from 150 °C to 200 °C, the wood became densified on both sides. The maximum density of the wood increased gradually with the increase of the temperature of the press plate. The longer the time of thermomechanical treatment, the more distant the maximum density area was from the wood surface. Depending on the temperature and the time of treatment, the hardness of the surface-densified birch wood was 1.4 to 2.2 times greater than the hardness of non-densified wood.

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“…Furthermore, in order to fix the compression set of densified wood and reduce spring back and dimensional instability, HTHT treatment under specific heating media has been proven effective and efficient in eliminating these negative problems (Gong et al 2010;Laine et al 2013a, b;Popescu et al 2014;Welzbacher et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…During their investigation on the Brinell hardness of surface-densified and hydrothermally modified wood, interestingly, it was found that the hydrothermal post-treatment reduced the elastic recovery of both the control specimens and surface-densified ones. Popescu et al (2014) evaluated the impact of the hydrothermo-mechanical (HTM) densification over the compression set recovery and thermal stability of lime wood. Their tests showed that the post-treatment at higher temperatures and longer durations improved the dimensional stability of the HTM samples, suggesting a permanent fixation of the transversal compression, but also reduced the thermal stability in the same context.…”

Section: Introductionmentioning

confidence: 99%

Transversal mechanical properties of surface-densified and hydrothermally modified needle fir wood

Zhan

Avramidis

2017

Wood Sci Technol

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Hydrothermal-mechanical (HTM) treatment is a combined action of temperature, moisture, and mechanical loads. Various kinds of HTM processes have been developed to produce eco-friendly modified wood products. Among these modification technologies, a combination of surface densification and hydrothermal post-treatment is a promising option that can be used to enhance plantation wood properties and generate value-added softwood products. This paper aimed to investigate the transversal dynamic transversal modulus of elasticity (dtMOE) profile and transversal density profile of surface-densified and hydrothermally posttreated needle fir (Abies nephrolepis) wood, and provide a practical guide for the processing optimization of surface-densified and thermally treated low-grade plantation softwood. Needle fir lumbers were surface-densified in an open hotpressing system, at a compression ratio of 16.1% and two hot-pressing temperatures (160 and 180°C) for a pressure holding duration of 10 min with a subsequent hydrothermal post-treatment at two temperatures (180 and 200°C) for 60 min. The transversal dtMOE profiles for six types of specimens (moisture-saturated, conditioned control, and four types of surface-densified specimens) were measured and analyzed by a dynamic thermo-mechanical analysis (DMA) apparatus. A dtMOE gradient variable (G M ) was defined herein to quantitatively formulate the dtMOE distribution of the surface-densified and hydrothermally post-treated wood specimens. Upon hot pressing, compressed cell tissues were observed within a 1.0-to 2.0-mm layer beneath the surface of the densified wood. The density peaks of compressed sections were increased to 650-800 kg/m 3 , compared with the average & Jian-feng Zhan density of the control specimens being at 350 kg/m 3 . The dtMOEs of the compressed sections were increased from 650 MPa of the control specimens, to 750-900 MPa, achieving the objective of surface densification. As the temperature of hydrothermal post-treatment increased from 180 to 200°C, the differences of the dtMOEs between the compressed surface sections and their inner adjacent ones decreased significantly, indicating the effective fixation of the compression deformations. Based on the test results obtained herein, it was concluded that the impact of the hot-pressing temperature and thermal post-treatment temperature over the dtMOE was insignificant. Nevertheless, it was also found that the hydrothermal treatment temperature showed significant influences over the dtMOE difference between the densified surface and its adjacent layer; the possible explanations for these complicated behaviors were also proposed herein.

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Evaluation of the thermal stability and set recovery of thermo-hydro-mechanically treated lime (Tilia cordata) wood

Cited by 29 publications

References 18 publications

A Review of the Characteristics of Small-Leaved Lime (Tilia cordata Mill.) and Their Implications for Silviculture in a Changing Climate

A Review of the Characteristics of Small-Leaved Lime (Tilia cordata Mill.) and Their Implications for Silviculture in a Changing Climate

The Influence of Process Parameters on the Density Profile and Hardness of Surface-densified Birch Wood (Betula pendula Roth)

Transversal mechanical properties of surface-densified and hydrothermally modified needle fir wood

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