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


pdf icon Use of Cellulose Sample for Material's Flammability and Pyrolysis Tests. (642 K)
Daikoku, M.; Venkatesh, S.; Saito, K.

Journal of Fire Sciences, Vol. 12, No. 5, 424-441, September/October 1994.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Keywords:

pyrolysis; cellulose; flammability tests; polymethyl methacrylate; thermal conductivity; cone calorimeters; radiation absorption

Abstract:

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 sample 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 experimental 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 similar to natural wood in order to eliminate a variety of experimental uncertainties due to inhomogeneity of particle board and wood samples for use in pyrolysis 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 radiation penetration effect into the porous structure in the pre-pyrolysis zone. Effect 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.