Leachability and Dimensional Stability of Nanosilver-Steamed Densified Poplar
G Rassam, A Talaei, A Ahmadi
This study was aimed to investigate leachability and dimensional stability of nanosilver impregnated poplar (Popolus alba), steamed before hot compression. Wood samples were impregnated with nanosilver suspension (200 and 400 ppm) under pressure of 4 bar for 20 minutes. Steam treatment was carried out at 150°C for 2 hours. Then samples were compressed (33%) radially in a hot press at 170°C for 30 minutes and cooled for 1 minute in compressed state. After densification process, spring back (immediately after press and after 15 and 30 days), long term water absorption and radial swelling after (2hr, 24hr, 48hr, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks) soaking in water were measured. Leaching test was carried out based on EN84, 1997. The results showed that steaming process before compression of samples caused fixation of nanosilver in compressed samples. It also improved water absorption and spring back. The least values of radial swelling belonged to nanosilver impregnated samples (with no steaming and compression treatments). Higher concentration of nanosilver (400 ppm) led to less spring back especially just after compression. There were no significant difference between 400ppm nanosilver treated samples at each time of measurement. Use of regression method and R-squared values proved that the linear function is perfectly fitted for predicting long term water absorption and radial swelling, considering different times of measurements, especially for nanosilver treated samples. By increasing the time of soaking, water absorption increased in all samples but nanosilver-steam treated samples had less absorption at all times (except after 48hr). Significant difference of radial swelling and spring back between 200 and 400ppm treated samples was only seen after 2 hour soaking in water.
Keywords: nanosilver, steam treatment, leaching, spring back, water absorption, radial swelling