Modification of Pinus sylvestris L. wood with quat- and amino-silicones of different chain lengths

The water-related properties of Scots pine (Pinus sylvestris L.) sapwood have been improved by treatment with quat- and amino-silicones of different chain lengths. Standard leaching test and hot water Soxhlet extraction (6 h) showed that the amino-silicones are better fixed in wood than the quat-silicones. A water dipping test (24 h) revealed that both quat- and amino-silicones made wood hydrophobic; however, amino-silicones were more effective in reducing water uptake. The long-chained silicones of both types resulted in higher water repellent effectiveness compared with the respective short-chained silicones. As demonstrated by assessing cell wall bulking, scanning electron microscopy (SEM), and SEM energy-dispersive X-ray analysis, silicones with short chains penetrated the cell wall better than those with long chains regardless of the silicone type. The maximum antishrink efficiency of approximately 60% was attained with short-chained amino-silicone at approximately 39% weight percent gain. The short-chained silicones show more potential to enhance the water-related properties of solid wood and for the development of silicone-based industrial wood modification processes.