Moisture-dependency of the fracture energy of wood: a comparison of unmodified and acetylated Scots pine and birch

Abstract The moisture-dependency of the fracture energy for unmodified and acetylated Scots pine ( Pinus sylvestris L.) birch Betula pendula Roth) has been investigated. Specimens were conditioned at relative humidity levels 20, 75, 97%, as well dry water-saturated. At moisture contents below 15%, increased with increasing content both wood, while it decreased untreated wood higher contents. A significant difference in was found, indicating compared to similar Additionally, assess impact brittleness structural applications, equal levels. largest seen 75% approximately 50% lower wood. No differences found water-saturated samples. energy, combined reduced hygroscopicity is suggested be one, but not only, contributing factor These observations have importance design since codes often material parameters based on ambient humidity.