Hydrothermal treatments to promote surface inactivation and increased flexibility in three hardwoods

Abstract

In the present study, three juvenile hardwoods (namely sycamore, pecan and london plane) were treated by boiling, steaming and microwave. Trees from Platanus x acerifolia (sycamore), Carya illinoinensis (pecan) and Luehea divaricata (london plane) were selected in homogeneous forests located in southern Brazil. Each hydrothermal treatment was performed for 60 min. In general, the hydrothermal treatments caused a certain surface inactivation effect, which was marked by decreased surface roughness, increased hydrophobic character and darkened colour patterns. Also, both decreased stiffness and strength, as well as increased deflectibility were obtained. These mechanisms were attributed to degradation in fine segments from amorphous polysaccharides, leaching of some organic extractives and fragmentation of lignin, as indirectly indicated by infrared spectra.

Bending quality of three Brazilian hardwoods modified by different hydrothermal treatments

“…The moisture content in the wood samples was measured before and after each treatment process using the gravimetric method described in ASTM D143 (ASTM, 2014). More information about the hydrothermal treatments can be obtained in previous studies of the group (de Peres et al, 2016;de Peres et al, 2020). Some curved wood specimens presented defects developed due to the bending process, namely crushing, splinting, cross cracking, and perpendicular break (Figure 3).…”

“…The samples were stored in a climatic chamber (at 65 % RH and 20 °C) until reaching constant mass. Further information from the selected woods can be consulted in previous studies from the research group (de Peres et al, 2016;de Peres et al, 2020) Aramburu et al…”

“…The greatest effect is related to the fibres, which undergo decreases in crosssectional area and wall thickness (Biziks et al, 2013). These anatomical changes yield decreases in mechanical properties of the wood, including modulus of elasticity, modulus of rupture, and brittleness (De Peres et al, 2020). These effects are favourable for the manufacture of curved wood samples.…”

Effects of various treatment methods on decay resistance and dimensional stability of nano-silver-treated Persian/Shiraz inlay (Khatam)

“…The moisture content of heartwood of sugar maple, American sycamore, and black walnut is approximately 65%, 114%, and 90%, respectively, and the moisture content of sapwood of sugar maple, American sycamore, and black walnut is approximately 72%, 130%, and 73%, respectively (Simpson and TenWolde 1999). The highest wettability for sycamore may be attributed to a capillary effect related to its large fibers or a high amount of amorphous cellulose components on its thick cell wall (De Peres et al 2020).…”