Thermal degradation of bending strength of plywood and oriented strand board: a kinet

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Thermal degradation of bending strength of plywood and oriented strand board: a kinetics approach

Author: Arijit Sinha• John A. Nairn• Rakesh Gupta | Size: 462 KB | Format: PDF | Quality: Unspecified | Year: 2009 | pages: 16

Abstract The construction industry has relied heavily on wood and wood-based composites, such as oriented strand board (OSB) and plywood for timber frame construction. Therefore, it is highly imperative to categorize the response of woodbased
composites when exposed to elevated temperatures for a sustained period of time. The essence of fire-resistant structural design is to ensure that structural integrity be maintained during and after the fire, prevent collapse and maintain
means of egress. Another aspect is to assess post-fire structural integrity and residual strength of existing structure. The objective of this project was (a) to study the effect
of exposure time on bending strength (MOR) of OSB and plywood at elevated temperatures, (b) to interpret any relationships between different temperature and
time of exposure using a kinetics model for thermal degradation of strength, and © to develop a master curve representing temporal behavior of OSB and plywood at a
reference temperature. As much as 1,152 samples were tested in static bending as a function of exposure time and several temperatures. Strength (MOR) of both OSB and plywood decreased as a function of temperature and exposure time. These results were fit to a simple kinetics model, based on the assumption of degradation kinetics following an Arrhenius activation energy model. The apparent activation energies for thermal degradation of strength were 54.1 kJ/mol for OSB and 62.8 kJ/mol for plywood. Furthermore, using the kinetics analysis along with time–temperature superposition, a master curve was generated at a reference temperature of 150.C which predicts degradation of strength with time on exposure at that reference temperature.

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