| Abstract: | Abstract Chitosan is a biopolymer derived from chitin in crustacean shells. Over the past decade it has been studied as an environmentally benign wood-protecting agent. It is assumed to act as a fungi-stat against a wide range of fungi and even as a fungicide at higher concentrations. This study investigated the properties of wood treated with modified chitosan of different molecular weights. Scots pine (Pinus sylvestris L.) and beech (Fagus sylvatica L.) samples were impregnated with two chitosan solutions differing in their average molecular weights. The chitosan solutions were depolymerized by nitrous acid to one solution of high molecular weight and one solution of low molecular weight with a concentration of 5% (w/v). The results show changes in sorption properties, antifungal properties, fire-retardant properties and mechanical properties of modified chitosan-treated wood. Heat-modified, chitosan-treated wood showed similar properties to chitosan-treated wood, except for brownish coloration, enhanced hydrophobation, and slightly reduced antifungal and fire-retardant properties. The modulus of rupture and hardness showed little or no change. The modulus of elasticity of the heat-modified, chitosan-treated wood increased by 27% compared with untreated wood. |
