Xin Liu and J.G. Quintiere

The flammability properties of nylon samples with different percentages of clay dispersed on the nanometer (molecular) scale were measured by a fire (cone) calorimeter. Specifically, chemical energy release rate, mass loss rate, and time to ignite (melt and char) were measured. This study consisted of samples of pure Nylon 6 and nylon that contained nanoclay additives at 2% and 5% by weight. In addition, the effect of sample thickness was considered for 1.6 to 24 mm. Data obtained over a range of radiant heat flux (17 to 55 kW/m2) were analyzed to illustrate the effect of sample clay loading and thickness on heat of combustion, heat of gasification, and ignition temperature. The findings indicated that the heats of combustion based on mass loss did not change with clay loading, and were 28 ±1 kJ/g. The critical heat flux for ignition did not appear to be influenced by the clay additive; it decreased from 17.7 for pure nylon to 16.0 with 5% clay addition. These values correspond roughly to an ignition temperature of 430° C, compared to a decomposition temperature range from a thermogravimetric analyzer of 350° to 430°C. However, the addition of the clay could increase the ignition time by 30% to 100% over the pure nylon. This is believed to be due to the increased char residue and the decrease in the mass loss rate. The char-like residue yield was nearly identical to the clay loadings. The overall average mass loss rate was reduced by up to 50% with a 5% clay composition over pure nylon for a given heat flux and thickness. For the clay nanocomposites, the burning rate increased as the thickness decreased.

Joshua L. Jurs

Novel flame-retardant chemical additives and polymers were synthesized and their flammability measured in the Underwriters Laboratory test for flammability of plastics (UL94). Self-extinguishing (V-0) compositions were obtained for poly (acrylonitrile-butadiene-styrene) and high-impact polystyrene by adding as little as 10 weight percent of boronic acid derivatives or halogen-containing bisphenylethenes (BPH). Self-extinguishing (V-2) compositions were obtained for polyethylene by adding as little as 10 weight percent BPH. The efficacy of BPH additives as flame-retardants suggested incorporating these moieties directly into the polymer to further reduce flammability. Polymers and copolymers were synthesized having BPH backbone and pendant groups, including backbone copolymers containing acetylene and phosphineoxide. The thermal combustion properties of polymers containing a BPH backbone or pendant groups were measured by microscale combustion calorimetry and found to be among the lowest values ever recorded, suggesting that aircraft cabin materials made from these polymers would be ultra-fire-resistant.

Patricia Cahill

The Federal Aviation Administration oil burner round-robin fire tests were conducted on aircraft seat cushions to determine the status of the test facilities that perform the tests. Two sets of fire-hardened foam and one set of fire-blocked foam test seat cushions were evaluated. The data showed that the weight loss and burn lengths were generally consistent in each individual laboratory. The most significant difference among all the laboratories was seen in the weight loss and burn lengths of the fire-blocked foam seat cushion. For two of the cushions there were a significant number of the laboratories that passed and failed the 10% average weight loss criteria.

Timothy R. Marker

Laboratory- and full-scale fire tests were conducted on a number of different types of aircraft seat cushion materials to determine the applicability of the current weight loss criteria specified in Title 14 Code of Federal Regulations Part 25.853(c) Appendix F Part II (herein referred to as Appendix F Part II) to new, very lightweight cushion designs. Cushion samples were initially tested in accordance with the current standard, and if they exceeded the 10% weight loss criteria, they were evaluated under full-scale fire test conditions. The full-scale tests were conducted with a modified narrow-body fuselage test article exposed to an adjacent fuel pan fire to simulate a severe but survivable postimpact cabin fire. Four triple-seat frames used to mount the cushion samples were installed inside the test article. Aircraft-grade honeycomb sidewall, ceiling panels, and carpet were also installed in the vicinity of the seat frames to simulate a realistic aircraft cabin.

Laboratory-scale tests were completed on one set of standard fire-blocked cushions that met the current Appendix F Part II requirement, in addition to four lightweight materials. The standard fire-blocked cushions were then run under full-scale conditions to provide a baseline of the current level of fire safety, followed by full-scale tests of the four lightweight materials. Results indicated that several of the lightweight seat materials that failed the weight loss criteria specified in Appendix F Part II did not result in greater fire hazards than the baseline materials when tested under realistic full-scale conditions. A conservative adjustment to the current weight loss criteria was developed to allow the use of very lightweight seat cushion materials that exhibit acceptable fire performance.

Harry Webster

This report documents the findings of a series of tests conducted to determine the flammability characteristics of rechargeable lithium-ion cells and the dangers associated with shipping them in bulk form on commercial transport category aircraft.