| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 693120 | Progress in Organic Coatings | 2013 | 9 Pages |
Heat-treated wood is value added product which attracted the attention of consumers due its dark brown color which is of interest for decorative purposes. But this dark brown color fades when subjected to outdoor environment turning to grayish white color along with formation of small cracks and checks on the surface. In order to prevent the color change, an effort has been put forward for developing new coatings. The acrylic polyurethane coating with bark extract with or without lignin stabilizer proved to be very effective in protecting the surface of heat-treated jack pine. In this study, the interaction of these coatings with heat-treated jack pine surface was investigated and the results were compared with those of industrially available Laurentide coating. The capillary penetration was found to be the most important phenomenon in wood-coating interaction. The results revealed that capillary penetration rate was highly dependent on different additives used as well as surface tension and viscosity of the coatings. Two different models were used to evaluate volume change of the coating drop with time which is the indication of capillary action during wetting on heat-treated jack pine. Influence of mechanical surface treatment also plays an important role in wetting phenomenon of wood coating irrespective of wood grain direction. Water penetration through coatings is very important for wood discoloration during aging. Therefore, measurement of contact angle between water and coated/heat-treated wood system gave insight to water penetration at different aging times. Furthermore, the degradation at wood-coating interface was studied using a fluorescence microscope which did not reveal any degradation at the interface for coating containing bark extract and coating containing bark extract together with lignin stabilizer. The results of this study give an insight into high performance of acrylic polyurethane containing bark extracts alone or together with lignin stabilizer against color change of heat-treated jack pine.
► Wetting and degradation behavior of PUA with natural antioxidant was studied during this work. ► Wetting behavior of coatings was highly dependent on capillary penetration rate. ► The lowest contact angle was obtained at mid grain size sanded wood surface. ► The highest water repellency was exhibited by coating with bark extract and lignin stabilizer. ► Color change occurred during accelerated aging was due to the degradation of wood surface layer beneath coating.
