Thermo-hydro treated (THT) birch plywood with improved service properties

Abstract

Thermo-hydro treatment (THT) of plywood produced from birch (Betula spp.) wood veneers was carried out in a multi-functional pilot device manufactured by WTT (Wood Treatment Technology). The treatment was conducted in elevated water vapour pressure conditions using four different treatment regimes: 150/10, 150/50, 160/10 and 160/50 (temperature, °C/duration, min). After the treatment, the THT plywood was subjected to the following tests: biological durability, anti-swelling efficiency (ASE), bending strength (BS), Brinell hardness (HB), equilibrium moisture content (EMC) and surface contact angle determination. THT improved most of the properties of the plywood. With increasing treatment severity, the dimensional stability and the resistance to white and brown rot fungi of THT plywood were improved. The EMC of THT plywood was lower than the untreated controls, and the surface became more hydrophobic. As a drawback, losses of BS and hardness were observed.

Properties of thermally modified teakwood

“…The thermal modification of wood is conducted using controlled heating at relatively high temperatures of 150 ºC to 260 °C (Grinins et al 2016).This treatment is used to improve dimensional stability, reduce hygroscopicity, and modify and standardize staining. However, as adverse result in wood, the mechanical properties decrease (Esteves and Pereira 2009), flammability increases (Čekovská et al 2017), mass is lost (Esteves and Pereira 2009) and chemical components are modified and broken (Weiland andGuyonnet 2003, Shi et al2018).…”

Heat treatment of poplar plywood: modifications in physical, mechanical and durability properties

“…Few authors looked at the thermal effect on EWP as (Sinha et al 2011) for fire resistance purposes rather than the use of this kind of product for exterior applications. Grinins et al (2016) considered the two possible approaches for producing thermally treated plywood: the first one being to treat the veneers separately before assembling them into the EWP; the second one being the treatment of the whole EWP. Afterwards, Lunguleasa et al (2018) considered, in an extensive experimental work, the possibility to thermally treat already glued beech plywood and to check the physical and mechanical properties of such a new product.…”