Development of fire retardant composite panels. Part VII. Improvement of fire performance of OSB panel via wood treatments with fire retardant, nano-particles and nanocrystalline cellulose
A series of randomly oriented three-layer strand boards were manufactured in the lab with five commercial fire retardants (CROS 349, CROS 334, BUDIT 380, CROS 481A, ZB-467), six commercial nano-particles (Cloisite 30B, Cloisite Na+, Nano Al2O3, zinc oxide, zinc oxide anion, zinc oxide non) and a sodium form of nanocrystalline cellulose in the surface layer. The resultant strand boards were evaluated for fire performance in terms of flame advance, weight loss (right after fire test) and insulation value (after fire test and conditioning), and mechanical and physical properties of board such as internal bond (IB) strength, dry and wet modulus of rupture (MOR) and modulus of elasticity (MOE), and 24-h thickness swelling (TS) and water absorption (WA).
It was observed that when applied at 6% for liquid form (for CROS 349, CROS 334, BUDIT 380) or 3% for powder form (for CROS 481A, ZB-467) on a dry wood basis, all fire retardants had an influence on board mechanical/physical properties and fire performance as well (in terms of insulation values rather than net flame advance and weight loss right after fire test). CROS 334 and BUDIT 380 performed better than others in terms of improved insulation property. In consideration of both board mechanical/physical properties and fire performance, BUDIT 380 would be optimal for strand board, while CROS 349 and CROS 334 also showed the potential for further investigation.
The use of 2% nano-particles in both dispersion and powder forms on a dry wood basis had no big influence on board fire performance. Cloisite 30B and Cloisite Na+ slightly improved the board fire performance in terms of reduced flame advance, but had a negative impact on board mechanical properties. All nano-particles also improved board insulation property at 0-inch test position. It is expected that an increase in application level of nano-particles would help to improve board fire performance.
Application of 1% nanocrystalline cellulose (NCC) in sodium form on a dry wood basis via spraying improved board mechanical/physical properties and also slightly improved board insulation property (rather than flame advance and weight loss). It is expected that an increase of NCC content in wood treatment would allow further improving board performance with regard to mechanical/physical properties and/or fire performance in terms of insulation property.