ELEVATED-TEMPERATURE OXYGEN INDEX APPARATUS AND MEASUREMENTS

An apparatus that performs elevated temperature (300-800-degrees-C Oxygen Index (OI) measurements using radiant heating has been developed and used to perform OI measurements on a variety of high-OI composite materials. Comparisons of data with OI values obtained using a gas preheat device indicate reasonable agreement. Flame propagation down the edges o the samples dominated the burning behavior for many high temperature samples. The physical mechanism of volatile release was identified as the con trolling factor for the OI value for high-OI materials. Delamination, cracking, matrix penetration, foaming, and blistering all led to different burning behavior and different OI characteristics. Long-term aging of composite materials is also a very important contributor to the OI of the material. At temperatures above 300-degrees-C OI values were found to be very high as a result of the stable nature of the carbon char remaining after decomposition of the polymeric binder material.