Effects of Pre-Freezing Prior to Drying upon Some Physical and Mechanical Properties of Eucalyptus urophylla × Eucalyptus grandis Wood

Liu, Hongda; Gao, Jianmin; Chen, Yao

doi:10.15376/biores.10.4.6417-6427

Cited by 13 publications

(6 citation statements)

References 19 publications

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“…Thought, smooth (A) nail type with the lowest mean value obtained the highest signi cant (p < 0.05) decrease for both tangential (69% and 63%) and radial (54% and 56%) directions, followed by a signi cantly decreased value obtained for helically treaded (B) type nail in both tangential (60% and 51%) and radial (54% and 34%) directions. The presented results for both spruce and larch wood are in concurrence with the results published by previous researchers who reported that freezing reduces certain mechanical properties of wood (Ilic 1995;Liu et al 2015). The values in parentheses are the standard deviations (SD).…”

Section: Moisture Content and Wood Densitysupporting

confidence: 91%

The influence of freezing on the nail withdrawal capacity of Norway Spruce and European Larch wood

Gašparík

Karami

Kytka

et al. 2022

Preprint

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Environmental conditions and temperature oscillations can influence wood properties. Accordingly, the performance of wood connections such as nails could be affected by freezing and heating temperature. Thus, in the present work, the impact of freezing/heating temperatures on the nail withdrawal power of Norway Spruce (Picea abies (L.) H. Karst.) and European Larch (Larix decidua Mill.) has been studied. Three types of the wood nail; smooth, helically threaded, and annularly threaded were studied, and two different freezing heating steps have been implemented (-15°C/70°C and − 25°C/70°C). Withdrawal capacity was distinguished on two various anatomical directions; radial and tangential surfaces. The freezing could cause a considerable destructive impact on the nail withdrawal capacity of both wood species. The highest drop has found for smooth nail (A) for larch wood in the tangential direction with 73% and 69% decrease and radial direction, with 70% and 63%, at temperatures − 15°C/70°C and − 25°C/70°C, respectively. Furthermore, spruce wood exhibited a meaningful reduction for both tangential (69% and 63%) and radial (54% and 56%) directions and smooth nail (A), at temperatures − 15°C/70°C and − 25°C/70°C, respectively. The highest reduction was found for annularly threaded nails (C).

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Section: Moisture Content and Wood Densitysupporting

confidence: 91%

The influence of freezing on the nail withdrawal capacity of Norway Spruce and European Larch wood

Gašparík

Karami

Kytka

et al. 2022

Preprint

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“…For one thing, like its counterparts poplar or pine in North China, eucalyptus is the most important plantation tree species in South China (Liu et al 2015). On the other hand, China has become the largest producer and consumer of various wood-based panels, of which about 50% the plywood (Fang 2014).…”

Section: Introductionmentioning

confidence: 99%

Developing and Evaluating Composites Based on Plantation Eucalyptus Rotary-cut Veneer and High-density Polyethylene Film as Novel Building Materials

Song¹,

Wei²,

Ren³

et al. 2016

BioResources

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To achieve value-added utilizations of plantation timbers, eucalyptus veneer/high-density polyethylene film composites were prepared, with process-factors (PF) (hot-pressing temperature, HT; hot-pressing duration, HD; hot-pressing pressure, HP; HDPE-film content, HC) and composite-properties (CP) (water-resistant bonding-strength, BS; modulus of rupture, MOR; modulus of elasticity, MOE) investigated. According to thermal analyses, 140 to 180 °C was appropriate for HT. Based on statistical analyses, HD was easier to affect CP, while MOE was easier to be affected by PF. Quantitative relationships between PF and CP were determined by the neural-network (ANN) modeling. In ANN simulation surveys, CP displayed Gaussian distributions (R 2 > 0.9) when PF changed in current ranges, with positive correlations between BS and MOR (R 2 ≈ 0.5). Combining ANN and the genetic-algorithm, optimal processes (HT, 160 °C; HD, 50 s/mm; HP, 1.3 MPa; HC, 6 layers) were found, and optimal results (BS, 1.30 MPa; MOR, 86.94 MPa; MOE, 8.33 GPa) were comparable to various reported poplar-plywoods. Microscopic images demonstrated that composite interfaces were formed by the mechanical interlocking. The optimal BS attained Chinese standards for water-resistant plywoods, so proposed composites can serve as waterresistant and formaldehyde-free building materials for furniture and interior design.

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“…Freezing does not allow water movement inside the cells' lumen, hampering the oxidation of extractives (LIU; GAO;CHEN, 2015).…”

Section: Resultsmentioning

confidence: 99%

“…The treatment results did not differ from the control, being the lowest retraction in the radial plane the treatments at -20°C exposed for 5 and 10 h when compared to the control. It is likely that water present in the wood freezes, causing an expansion of the cells' lumen that can generate stress in the cellular walls, thus making them more rigid and reducing contraction (LIU; GAO;CHEN, 2015).…”

Section: Temperature(°c)mentioning

confidence: 99%

Effect of Hydrothermal and Freezing Treatment on the Physical and Mechanical Properties of Eucalyptus Wood

et al. 2017

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-Wood, in general, is a material with excellent properties; however, some features may limit its use. In this sense, various thermal treatments are emerging as alternatives to improve the technological properties of wood. In this context, this study aims at analyzing the effects of time and temperature (hydrothermal treatment and freezing) on the physical and mechanical properties of Eucalyptus grandis W. Hill ex Maiden. Three trees were selected, and only the heartwood was used to obtain the test body dimensions of 30 × 8 × 3 cm (length × width × thickness). The treatments were carried out at three temperatures of -20, 60, and 100°C, each at three exposure times (5, 10, and 15 h). Temperature treatment at -20°C was conducted in a domestic freezer, while the treatments at 60 and 100°C were administered in a Parr reactor, where the timber was submerged in water. Regardless of the exposure time, the timbers heat-treated at 100°C showed more efficiency, since this treatment unclogged the pores, reduced hygroscopicity, and promoted further darkening and uniformity of color, without changing the density and mechanical strength of the wood. Keywords:Heartwood. Parr reactor. Heat treatment. EFEITO DO TRATAMENTO HIDROTÉRMICO E CONGELAMENTO NAS PROPRIEDADES FÍSICAS E MECÂNICAS DA MADEIRA DE EUCALIPTORESUMO -A madeira, de modo geral, é um material com excelentes propriedades, mas ressalta-se que algumas características podem limitar o seu uso. Neste sentido, alguns métodos de tratamentos térmicos vêm surgindo como alternativa para melhorar algumas propriedades tecnológicas da madeira. Neste contexto, o objetivo do trabalho foi avaliar o efeito do tempo e da temperatura do tratamento hidrotérmico e do congelamento nas propriedades físicas e mecânicas da madeira de Eucalyptus grandis W.Hill ex Maiden. Foram utilizadas três árvores, selecionando-se apenas a madeira do cerne para obtenção dos corpos de prova de dimensões 30 x 8 x 3 cm (comprimento x largura x espessura). Os tratamentos foram realizados nas temperaturas de -20, 60 e 100 °C combinados a três tempos de exposição (5, 10 e 15 horas). O tratamento na temperatura de -20 °C foi realizado em um freezer doméstico, e os tratamentos a 60 e 100 °C em um Reator Parr, onde as madeiras ficaram submersas em água. Independente do tempo de exposição, os tratamentos realizados a 100 °C mostraram-se mais eficientes, pois desobstruíram os poros, reduziram a higroscopicidade e promoveram maior escurecimento e homogeneização da cor das madeiras, sem alterar a densidade e a resistência mecânica das mesmas.Palavras-chave: Madeira de cerne. Reator parr. Tratamento térmico.

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Effects of Pre-Freezing Prior to Drying upon Some Physical and Mechanical Properties of Eucalyptus urophylla × Eucalyptus grandis Wood

Cited by 13 publications

References 19 publications

The influence of freezing on the nail withdrawal capacity of Norway Spruce and European Larch wood

The influence of freezing on the nail withdrawal capacity of Norway Spruce and European Larch wood

Developing and Evaluating Composites Based on Plantation Eucalyptus Rotary-cut Veneer and High-density Polyethylene Film as Novel Building Materials

Effect of Hydrothermal and Freezing Treatment on the Physical and Mechanical Properties of Eucalyptus Wood

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