The effect of impregnation with fire retardant on the properties of particleboard bonded with PF/pMDI adhesive

The application of commonly used flame retardants in most cases causes reduction in strength characteristic of particleboard. Therefore, it was decided to carry out research aimed at determining possibility of using pMDI-reinforced PF adhesive to produce board with increased fire resistance. The effect of different shares of particles impregnated with a mixture of potassium carbonate and urea on the particleboard properties such as density, density profile, bending strength, modulus of elasticity, internal bond and internal bond after boiling was investigated. Presented work also determined the effect of fire retardant on the performance of particleboards after ageing test and their reaction to fire. Studies demonstrated that PF adhesive modified with 20% pMDI is suitable for gluing impregnated wood particles. Regardless of their share, resultant panels showed no changes in strength and density. In the case of boards consisting of impregnated particles in the amount of 75% and 100%, lower values of swelling were demonstrated. The boards were classified as load-bearing boards for use in humid conditions. Fire retarding efficiency was confirmed by lowered mass loss, prolonged time needed to reach maximal burning rate, decreased gross calorific value and reduced ignitability when exposed to both radiant heat source and small flame source.