Surface properties of extracts from cork black condensate

Abstract

The insulation corkboard production generates black condensate (BC), a paste-like solid waste. It is hydrophobic and has the potential to be used as protective coating. To evaluate this potential, coatings were prepared from BC extracts and their surface behavior was evaluated by contact angle (CA) measurements. The CA dynamics were recorded as a function of time; advancing CAs were also registered; the approaches were applied according to Fowkes, Owens- Wendt-Rabel-Kaelble (OWRK), and Van Oss to determine the surface energy (SE) for each coating. Depending on the liquid probe, three phenomena were observed: water evaporation, diiodomethane diffusion into the coating, and rearrangement of the chemical groups on the coating surface, when glycerol was dropped onto the surface. Based on the results from the CA dynamics, the applicability of the coatings against hydrophobic environments was limited owing to its affinity to apolar compounds. The results show that the coating prepared by the toluene BC extract was the best coating. The key data were: water CA of 99.38, total SE (between 37.4 mN m-1 and 40.1 mN m-1), SE polar component (0.1 mN m-1), and the acidic and basic characters were negligible. It can be concluded that the BC extracts have potential for coatings.