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Surface temperature of decomposing construction materials studied by laser‐induced phosphorescence

Measurements of surface temperature and mass loss of decomposing construction materials during rapid pyrolysis are presented. Experiments have been performed with samples of low‐density fiberboard, medium‐density fiberboard, particleboard and poly(methyl methacrylate) in a single particle reactor at temperatures between 300° and 600°C. Ultraviolet laser light was used to excite micrometer‐sized thermographic phosphor particles that were deposited on the investigated materials, and the temperature was obtained from temporally resolved measurements of the laser‐induced emission. The wood‐based materials show a similar behavior, with small differences being attributed to differences in material properties. The surface temperature rapidly increases to about 400°C when a particle is introduced to the hot reactor. The initial phase is followed by rapid decomposition during which the surface temperature is 380°–540°C. The heating rate is slowed down during the rapid pyrolysis, and again increases as the remaining char is heated to the reactor temperature. The poly (methyl methacrylate), however, melts and at high temperatures can be characterized as a liquid with a boiling point of about 400°C. Thermographic phosphors are concluded to be suitable for high precision remote measurements of the surface temperature of decomposing construction materials, and possibilities for further studies and developments of the technique are discussed. Copyright © 2004 John Wiley & Sons, Ltd.