The Use of Cellulose Sample for Material's Flammability and Pyrolysis Tests

During transient pyrolysis tests of charring and non-charring materials, we noticed that sample preparation is crucial to obtain reliable data, on which theoretical models are based. Different researchers use different sam ple preparation techniques which some time causes disagreement in the results and create ambiguity when test results are compared. In this paper, we propose a bench mark sample preparation technique to clarify the experimen tal ambiguity and establish a reliable/common data base. Pyrolysis tests were performed by exposing PMMA, douglas-fir particle board (DFPB), and cellulose samples to external radiant heat using quartz and cone heaters. The cellulose sample is suggested for its homogeneity and combustion characteristics simi lar to natural wood in order to eliminate a variety of experimental uncertain ties due to inhomogeneity of particle board and wood samples for use in pyroly sis tests. Temperatures were measured at the front and back surfaces and at other intermediate locations using fine thermocouples. Thermal conductivity of DFPB and cellulose was then approximated from the measured temperature distributions as the sum of a linear temperature dependent term and a radia tion penetration effect into the pourous structure in the pre-lyrolysis zone. Ef fect of in-depth radiation absorption through the surface of the PMMA samples was estimated for various external radiant heat flux values; and it was found that in-depth radiation is an important factor in controlling the rate of heat transfer into the sample.