Understanding the effect of extractives on the mechanical properties of the waterborne coating on wood surface by nanoindentation 3D mapping

• Published in: Journal of materials science 2021, Vol.56 (2), p.1401-1412
• Main Authors: Wu, Yan, Zhang, Haiqiao, Yang, Lechen, Wang, Siqun, Meng, Yujie
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Coatings; Composites & Nanocomposites; Crystallography and Scattering Methods; Extraction procedures; Mapping; Materials Science; Mechanical properties; Modulus of elasticity; Nanoindentation; Permeability; Polymer Sciences; Solid Mechanics
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-020-05347-2

The extractives in wood have been proved to have some effect on the permeability and adhesive quality of the waterborne coating. Due to the hydrophobic property of extractives, water in aqueous coatings does not easily enter the wood cell wall, which affects the performance of the waterborne coating. Herein, a nanoindentation 3D mapping experiment was performed on the bonding areas between the waterborne coating, extractive-free wood and control wood, respectively. The variability of the reduced elastic modulus ( E r ) and the hardness ( H ) was evaluated for an area of 100 μm by 100 μm. Overall, the E r and H of the waterborne coating were different from the values of wood. It demonstrated that the extraction procedure had a negative impact on the E r and H of the waterborne coating. The average values of E r and H of the coating area were both higher when coated on the control wood sample surface ( E r : 2.836 GPa, H : 0.105 GPa) than on the extractive-free one ( E r : 2.390 GPa, H : 0.079 GPa). However, the average values of E r and H in the wood increased by 50.43% and 33.67% after extraction, respectively. This study will help to understand the adhesion mechanism of the interface between the waterborne coating and the wood.