How change some properties of poplar wood surface with extractives of durable wood species.

All woods contain extractives and they may include hydrolyzable or condensed tannins, flavonoids, lignins, stilbenes, faty acids, resin acids, other complex terpenoids, waxes, sterols, sugars, cyclitols and starch. The extractives ofen are the main responsible of many characteristics and possible uses of wood, such as colour, flammability, hygroscopicity and permeability. The wetability of wood is an important parameter that provides a series of information on the interaction between the wood surface and liquids, such as water or adhesives. In this work the contact angle of a sessile drop and the colour stability of the poplar (Populus spp.) wood surface afer immersion and afer accelerated weathering test into five types of extractives obtained from durable wood Castanea sativa Mill., Cedrus deodara Roxb., Qercus fraineto Ten., Qercus petraea Liebl. and Larix decidua Mill. were investigated. Extraction was carried out with a mixture of water and ethanol (30:70 v/v) by extraction system ASE 100 at 110° with a pressure of 100 bars. For each extractives solution three replicas have been done and five drops have been recorded. Distilled water for the contact angle afer immersion and afer accelerated weathe - ring test was used for a time of 120 sec. The color change of the specimens were also measured in form of CIE L*a*b* before and afer accelerated ageing to determine changes in lightness (ΔL), colorimetric parameters Δa, Δb, and overall color (ΔE). The results revealed that poplar wood surface were diferentially afected by the spe - cies afer immersion. Afer accelerated weathering test the efect of extractives on wetability disappeared. In terms of the colour diference (ΔE), afer immersion the smallest value has been observed when extractives of cedar and larch were used. However, the same extractives afer accelerated ageing, showed a higher value of ΔE compared to the other extractives. In fact, afer ageing, the extractives of chestnut and both oak, conferred a more stable color of poplar wood surface. In conclusion this study showed that some types of extractives could be used as a natural compound to change the absorption of the water and the colour stability.