Investigation of Factory Fire Retardant Treatment of Eucalyptus Plywood

Abstract Eucalyptus has become an important substitute material for the burgeoning plywood industry in China, whereas the corresponding fire retardant–treated products remain to be developed. This study preliminarily evaluated the feasibility of manufacturing fire retardant–treated eucalyptus plywood in the traditional industrial plant by veneer impregnation. Eucalyptus saligna and Eucalyptus dunnii veneers were impregnated by a commercial fire retardant at room temperature and atmospheric pressure. After redrying, the veneers were hot pressed into fire retardant–treated plywood in a conventional way. Fire performance was evaluated by cone calorimeter test. Basic properties (i.e., moisture content, bonding strength, and formaldehyde emission), mechanical properties (including modulus of rupture and modulus of elasticity), and hygroscopicity were also investigated. The fire retardancy of plywood was significantly improved by the fire retardant treatment, in terms of decreased heat release rate and increased residual mass fraction. The flame spread index values for plywood, which were calculated from the results from cone calorimeter tests, indicate that the fire performance of plywood improves from Class III to Class II after the treatment. The basic properties of fire retardant–treated plywood meet the requirements of GB/T 9846 (Standardization Administration of the People's Republic of China 2004). The mechanical and hygroscopic properties of fire retardant–treated plywood satisfy demands of general interior applications. The veneer treatment could be a suitable approach for Eucalyptus plywood factories to manufacture fire retardant–treated products.