Natural weathering performance of three fast-growing Eucalypt woods

Abstract

We investigated the effect of outdoor exposure on the wood surface from three fast-growing Brazilian eucalypts through color, wetting and thermal analyzes. Gympie messmate (Eucalyptus cloeziana), rose gum (Eucalyptus grandis) and blue gum (Eucalyptus saligna) woods were exposed outdoors in a subtropical region for 360 days. We performed three collections every 120 days. We investigated color changes of untreated and weathered woods through a spectrophotometer (CIEL*a*b* system) and changes in macro compounds of wood through thermogravimetric analysis. In addition, the apparent contact angle and work of adhesion were evaluated using a goniometer. Outdoor exposure for 120 days provided significant increment in grayish of wood surface. Thermogravimetric curves of wood changed after the weathering, especially in the regions related to hemicelluloses and lignin thermal degradation. Outdoor exposure for 360 days converted hydrophilic wood surface into a very hydrophilic one, wherein occurrence of microcracks contributed to fully spreading of water droplets.

Effectiveness of Two Different Hydrophobic Topcoats for Increasing of Durability of Exterior Coating Systems on Oak Wood

“…Ten measurements per sample were performed after 1, 3, and 6 weeks of weathering with distilled water drops with a dosing volume of 5 µL. The value of contact angle was recorded in 5 sec after drop deposition on the surface as in other studies [37][38][39]. The phenomena of spreading and absorption of water drops on the oak wood surface was investigated via variations of the weathering time, coating system and applied hydrophobic layer.…”

Efficacy of Hydrophobic Coatings in Protecting Oak Wood Surfaces during Accelerated Weathering

“…Ten measurements per sample were performed after 1, 3, and 6 weeks of weathering with distilled water drops with a dosing volume of 5 µ L. This was done in order to minimise the effects of the structural and chemical variations of the wood samples. As in other studies [63][64][65], the contact angle measurements were done at 5 s after the deposition of the water drop on the surface. The phenomena of spreading and absorption of drops on the wood surface was investigated using a variation of the artificial weathering time and the type of surface treatment.…”

Surface Wettability of Wood Species from Tropical and Temperate Zones by Polar and Dispersive Liquids

“…Wettability of wood is described by a number of parameters, of which the most studied and analysed are contact angle and surface free energy. Only a few authors examine wetting energy, spreading coeffi cient of reference liquid, work of adhesion for the phase boundary wood-liquid, surface tension of the liquid (Zhang et al, 1997;Kocaefe et al, 2008;Wolkenhauer et al, 2009;Gonzalez de Cademartori et al, 2015).…”