Moisture behavior and structural changes of plywood during outdoor exposure

Published Date
Original

First Online: 

28 November 2015

DOI: 10.1007/s00107-015-0992-z

Cite this article as: 

Li, W., Van den Bulcke, J., De Windt, I. et al. Eur. J. Wood Prod. (2016) 74: 211. doi:10.1007/s00107-015-0992-z

Author 

Wanzhao Li, 

Jan Van den Bulcke, 

Imke De Windt, 

Jelle Dhaene, 

Joris Van Acker

Abstract

Plywood is an important wood-based construction material yet prone to water uptake, as such potentially decreasing mechanical properties and increasing decay risk. It is therefore, essential to understand the moisture behavior and structural changes of plywood in service. In this research, several plywood specimens were exposed to outdoor weathering conditions for approximately 1 year. During this period, the average moisture variation of and moisture distribution in different veneer layers of a set of plywood specimens and detailed field weather information were recorded continuously. The internal structure of the specimens was also monitored by periodically scanning using X-ray CT. Measurements indicate that moisture distribution in plywood is not homogeneous in outdoor conditions. The second layer can, in some plywood types, accumulate a significant amount of rain, and long rainy periods and cloudy weather can keep the moisture content of the inner layers of plywood significantly high. Moisture accumulation and moisture dynamics, in combination with wood species, are the main factors causing structural changes, mainly occurring as cracks, of the plywood veneers in service. The glue line between the veneers, however, is not ruptured after 1 year of outdoor exposure. Plywood with layers having a slow water sorption and fast water desorption could effectively avoid internal moisture accumulation and cracks in service. Based on the knowledge of the interrelationship of weather data, internal moisture behavior and structural changes in service, fit-for-purpose design of plywood could be improved and service life prediction is at hand.

References

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Gold deposition on magnetic porous composites synthesized from modified wood sawdust at different temperatures

Published Date
Original

First Online: 

14 May 2015

DOI: 10.1007/s00226-015-0733-9

Cite this article as: 

Tsyganova, S., Patrushev, V. & Zhizhaev, A. Wood Sci Technol (2015) 49: 869. doi:10.1007/s00226-015-0733-9

Author

Svetlana Tsyganova, 

Valery Patrushev, 

Anatoly Zhizhaev

Abstract

In this work, porous magnetic carbonic composites with a surface area of 1000–1350 m2/g were prepared during carbonization of wood sawdust modified by chlorides of iron and zinc at temperatures of 400 and 800 °C. It was shown that capacity of the samples with respect to gold deposited from HAuCl4 solution is 0.3–0.5 g/g and depends on the carbonization temperature of the synthesized composite. Moreover, amount of gold deposited on the composite correlates with the magnetite content. It is assumed that one reason for the high capacity of composite with respect to gold is interaction of chloroaurate ions with magnetite phase contained in composite. It was noted that morphology of gold on the sample surface depends on synthesis temperature of composite: Gold deposited on porous composite obtained at a temperature of 400 °C is in the form of radiant-needle particles, and spherical particles of gold are formed at the composite surface obtained at the temperature of 800 °C.

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Investigating water transport in MDF and OSB using a gantry-based X-ray CT scanning system

Published Date
Original

First Online: 

07 September 2016

DOI: 10.1007/s00226-016-0855-8

Cite this article as: 

Li, W., Van den Bulcke, J., De Schryver, T. et al. Wood Sci Technol (2016). doi:10.1007/s00226-016-0855-8

Author 

Wanzhao Li, 

Jan Van den Bulcke, 

Thomas De Schryver, 

Joris Van Acker

Abstract

Both medium density fiberboard (MDF) and oriented strand board (OSB) are important engineered wood products. Water uptake can decrease their physical and mechanical properties as well as induce fungal decay. It is therefore essential to understand the water transport behavior in these products in detail. In this research, a state-of-the-art gantry-based X-ray CT scanner was used to investigate the water transport and the internal microstructure of the specimens from different types of MDF and OSB during water uptake. The results show that water, obviously, is mainly absorbed from the sides of all specimens during immersion testing. Water can reach the interior of the small specimens within 1 h through large fibers and strands. Although water movement through voids is slow, high water content can be reached when these voids are filled; for example, moisture content of more than 100 % is found in MDF. A compact structure can effectively decrease water accumulation in voids. Furthermore, the presence of a water-resistant adhesive, a water-repellent additive and acetylated fibers clearly influences water transport behavior in wood fibers and voids, increasing water resistance and improve structural stability of MDF. Moisture dynamics of OSB are different, among others influenced by orientation of the strands: grain direction perpendicular to the water uptake direction can protect OSB from water penetration. Furthermore, strands covered with resin have a good water resistance.

References

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14. Li WZ, Van den Bulcke J, De Windt I, Van Loo D, Dierick M, Brabant L, Van Acker J (2013) Combining electrical resistance and 3-D X-ray computed tomography for moisture distribution measurements in wood products exposed in dynamic moisture conditions. Build Environ 67:250–259CrossRef
15. Li WZ, Van den Bulcke J, Mannes D, Lehmann E, De Windt I, Dierick M, Van Acker J (2014) Impact of internal structure on water-resistance of plywood studied using neutron radiography and X-ray tomography. Constr Build Mater 73:171–179CrossRef
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17. Masschaele B, Dierick M, Van Loo D, Boone MN, Brabant L, Pauwels E, Cnudde V, Van Hoorebeke L (2013) Hector: a 240kv micro-ct setup optimized for research. In: 11th International conference on X-Ray microscopy, vol 463. Shanghai
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Wood Science and Technology

Published Date

Journal of the International Academy of Wood Science

ISSN: 0043-7719 (Print) 1432-5225 (Online)

Description

Wood Science and Technology publishes original scientific research results and review papers covering the entire field of wood material science, wood components and wood based products. Subjects are wood biology and wood quality, wood physics and physical technologies, wood chemistry and chemical technologies. Latest advances in areas such as cell wall and wood formation; structural and chemical composition of wood and wood composites and their property relations; physical, mechanical and chemical characterization and relevant methodological developments, and microbiological degradation of wood and wood based products are reported. Topics related to wood technology include machining, gluing, and finishing, composite technology, wood modification, wood mechanics, creep and rheology, and the conversion of wood into pulp and biorefinery products.

The Editor-in-Chief is Klaus Richter, Holzforschung München, Technische Universität München, Germany; The Co-Editor-in-Chief is Robert Evans, Silvi Scan Pty. Ltd., Australia

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Contributions to the orchid flora of Thailand IX

Published Date

• First published: April 1981
• DOI: 10.1111/j.1756-1051.1981.tb00691.x

Author
Gunnar Seidenfaden

Abstract

In continuation of earlier papers in this series, published in the now discontinued Botanisk Tidskrift Vol. 65–72, 1969–1977, additions and corrections to earlier papers on East Asiatic orchids are supplied. Seven new species are proposed, of which five from neighboring countries, and further seven new records for Thailand are listed. The five species alien to Thailand may be expected to be found also in Thailand. Some nomenclatural changes and new synonyms are proposed. An attempt is made to clarify taxonomical and nomenclatural problems on some entities in the Rhopalanthe section of Dendrobium.


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The orchid flora of Cocos Island National Park, Puntarenas, Costa Rica

Published Date

• First published: 13 April 2011
• DOI: 10.1111/j.1095-8339.2011.01127.x

Author
DIEGO BOGARÍN,
JORGE WARNER,
MARTYN POWELL,
VINCENT SAVOLAINEN

E-mail: diego.bogarin@ucr.ac.cr

Abstract

The orchid flora of Cocos Island National Park, Costa Rica is described based on field collections and herbarium sampling. Cocos Island is an oceanic island situated 550 km south-west of Puntarenas (the main Costa Rican port on the Pacific coast) and 680 km north-east of the Galápagos Islands. Five species of orchids were recorded in this small area of 24 km2: Camaridium micranthum and Ornithidium adendrobium (both formerly included in Maxillaria) and three endemic species of Epidendrum (E. cocoense, E. insulanum and E. jimenezii). The species are described and analytical illustrations are provided for each. A key to the species for field identification based on morphology is presented. Biogeography, ecology, taxonomy, evolution and conservation status of the species are also discussed. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 166, 20–39.


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A collection of orchids from Malaya

Published Date

• First published: May 1986
• DOI: 10.1111/j.1756-1051.1986.tb00872.x

Author
Gunnar Seidenfaden

Abstract

A collection of Malayan orchids made by Dr Peter Vaughan in 1980–81 proved to contain several interesting and noteworthy species, including about 10 species new to Malaya.


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A taxonomic revision of Encyclia (Orchidaceae: Laeliinae) in Costa Rica

Published Date

• First published: 5 March 2012
• DOI: 10.1111/j.1095-8339.2012.01212.x

Author
FRANCO PUPULIN,
DIEGO BOGARÍN

Abstract

A taxonomic revision of Encyclia (Orchidaceae) in Costa Rica is presented. The taxonomic history of the genus and its phylogenetic position are discussed. Characters of vegetative and floral morphology are described and their taxonomic significance is discussed. The genus is treated as comprising nine species in the country and a key to species is provided. Each taxon is described on the basis of Costa Rican material, illustrated in a composite plate, and its distribution within the country is assessed. Distribution maps for all the taxa are given. Overall distribution, derivation of name, synonymy, notes on species ecology and diagnostic features are presented for each taxon. The names Encyclia tonduzianaand Epidendrum mooreanum are typified. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168, 395–448.


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Thirteen new species of Dendrochilum (Orchidaceae), a new record from Burma, and a checklist of the genus in East Malesia

Published Date

• First published: August 1995
• DOI: 10.1111/j.1756-1051.1995.tb00168.x

Author
Henrik Ærenlund Pedersen

Abstract

Pedersen, H. Æ. 1995. Thirteen new species of Dendrochilum (Orchidaceae), a new record from Burma, and a checklist of the genus in East Malesia. — Nord. J. Bot. 15: 381402. Copenhagen. ISSN 0107–055X.

Seven new species of Dendrochilum are described from the Philippines, viz. D. amesianum, D. flexuosum, D. louisianum, D. parvipapillatum, D. plocoglottoides, D. quisumbingianum and D. tetradactyliferum. The widespread species D. longifolium is recorded from Burma for the first time, and an annotated checklist of Dendrochilumin East Malesia, i.e. the Lesser Sunda Islands, Sulawesi, the Moluccas, and New Guinea is given. This list enumerates a total of 21 species, including D. cornutum and D. pallideflavens which are here recorded from East Malesia for the first time. Six species in the checklist are described as new, viz. D. ambangense, D. citrinum, D. erectila-bium, D. eymae, D. galeatum, and D. longipedicellatum.

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