Wood belongs to the natural bio-composites of plant origin containing cellulose, hemicelluloses, lignin and other compounds. When exposed to fire or any other high intensity heat sources, wood, being a natural polymer, is subject to thermal decomposition (pyrolysis) and combustion depending on the environmental conditions. Combustion accompanied by heat release and chemiluminescence occurs when wood is in direct contact with air and with a physical, chemical or microbiological stimulus associated with heat release. There are increasing concerns about the fire performance of engineered wood products (EWP) and wood composite products such as oriented strand board (OSB), particleboard (PB), medium density fiberboard (MDF) and high density fiberboard (HDF) panels. Wood composite panels, like structural wood products, should have certain fire retardant properties with respect to both safety and the environment. It is believed that this issue will get more attention in the near future as environmental regulations are developed and the requirements of end-users change.
A Canadian Forest Service (CFS) project in the Composites Program, entitled “Development of Fire Retardant Composite Panels (Project No. 5764),” was initiated in 2007. The aim of the project is to develop fire retardant OSB panel and low-density fiberboard (FB) through modification of wood furnish and/or adhesives using fire retardants and nano materials, and to improve the fire performance of panel surface coatings by using fire retardant coatings and paints. As part of the project deliverables, this report presents a review of the current literature focused on the identification of proprietary fire retardant-treated wood and wood-based products, plywood, oriented strand board (OSB), particleboard, hardboard and fiberboard, low-density fiberboard panels suitable for use as interior ceiling finish, and other composite wood products used in construction of buildings, and the identification of potential new manufacturing processes for such products.
The literature review was conducted by Mr. Leslie R. Richardson, retired senior research scientist and Group Leader of Building Systems – Fire Program of FPInnovations - Forintek Division. It is believed that this literature review will be an invaluable guide for acquiring information on fire performance requirements and standard fire test methods for wood and composite wood products. The full literature review is available in Appendix.
The work described in this report involved examination of the development of IB strength in OSB panels as a function of pressing parameters and mat moisture content. Response surface methodology (RSM) was used in the design the experimental work employing a Box-Behnken design with four (4) variables (platen temperature, pressing time, moisture content (MC) of the face layers of the mat and face/core ratio).
Results showed that the relationships between the study parameters and IB strength fit very well the form of quadratic polynomials. Within the limits studied, it was found that increasing the pressing time and/or temperature could significantly improve the IB strength in OSB panels. Also, the study showed that bonding strength is improved by reducing mat moisture content.
It recommended that the study proceed as planned, using a thermal analysis technique (DSC) to compare the chemical reactions and curing behaviour of some commercial PF resins. Also, lap-shear tests, will be employed to evaluate strength development of the adhesives as function of time, temperature and furnish moisture content. It also recommended that a bench-making will be proceeded at laboratory and mill scale to verify the model.
This final report summarises progress in the fourth and final year of this multi-year project intended to characterise the fire performance of decorative wood room-linings and finishes. Forintek is often asked when decorative wood panelling is permitted in our export markets as a wall lining, a ceiling lining and as wainscoting. The question is challenging because both building code requirements and fire test methods for room linings vary from country to country.
A literature review was undertaken that demonstrated that different countries apply different test methods to regulate the use of combustible interior finish. The single-burning item test is used in Europe and is likely to be adopted in China; the cone calorimeter test is used in Japan, Australia and New Zealand; and the Steiner tunnel test is used in North America. Since Canadian wood products are sold in a variety of markets, it was decided that Forintek should document how they perform in each of these tests.
As globalisation intensifies, there is much interest internationally in comparing the performance of products as assessed by the different test methods used in various jurisdictions in order to facilitate trade. The room-corner test is proving useful in this regard. Although expensive and time-consuming to run, of all the test methods used to quantify the performance of lining materials, it is most representative of real-world fire scenarios. Consequently the room-corner test has become a reference scenario whereby the results generated in other tests can be understood. In fact, as countries move towards harmonisation of standards, there is a tendency to base product acceptance on performance in either the national fire test method or in the ISO room-corner fire test.
An agreement was made with Southwest Research Institute (SwRI) to conduct tunnel tests (ASTM E84), cone calorimeter tests (ISO 5660 / ASTM E1354), single-burning-item tests (SBI / EN 13823) and room-corner tests (ISO 9705) on several wood products. The wood products were white pine boards, white oak boards, OSB, Douglas fir plywood and FRT Douglas fir plywood. Due to equipment problems, the final report was not forwarded to Forintek until March 27. This has left little opportunity for analysis of the results. However, Forintek scientists have reviewed some of the raw data and have concluded that, in the reference scenario, the room-corner test, wainscoting performs very well.
A detailed analysis of the test data generated for Forintek by SwRI will be undertaken and an amendment to this final report will be made by the end of the First Quarter in 2006-2007.
The results of this study will allow Forintek scientists to respond appropriately to questions from members about when decorative wood panelling is permitted in our export markets. Because the project has involved testing in the internationally sanctioned reference scenario, the room-corner test, the results of the study also allow Forintek to recommend where it may be possible to recommend relaxations in requirements for room lings and wainscoting in our international markets.