Fire Safety Applications Research Articles

Polyelectrolyte/Nanosilicate Thin-Film Assemblies: Influence of pH on Growth, Mechanical Behavior, and Flammability

Thin composite films of branched polyethylenimine (BPEI) and Laponite clay platelets were prepared using layer-by-layer assembly. The film thickness was tailored by altering the pH of the aqueous mixtures used to deposit these films, resulting in growth that ranged from 0.5 to 5 nm/bilayer (BL). High-pH BPEI and low-pH clay produced the thickest films. The microstructure of tilted Laponite clay platelet stacks is observed with transmission electron microscopy when using unadjusted BPEI (pH 10.3) and pH 6 Laponite. This recipe resulted in a film with 83 wt % clay and a hardness of 0.5 GPa. In all films, the clay platelets are uniformly deposited and look analogous to a cobblestone path in atomic force microscopy surface images. Several 40-BL films, with thicknesses of 100 nm or more, exhibit reduced moduli ranging from 7 to 10 GPa and hardness of around 0.5 GPa, suggesting that these transparent films could be useful as hard coatings for plastic films. These thin coatings were also deposited onto cotton fabric. Each individual cotton fiber was uniformly coated, and the fabric has significantly more char left after burning than the uncoated fabric. Thermogravimetric analysis results reveal that fabric coated with 10 BLs of BPEI/Laponite produces up to 6 wt % char at 500 degrees C, which is almost 1 order of magnitude greater than that of untreated fabric. This initial study demonstrates that polymer/clay assemblies could improve the thermal stability of cotton and may be useful for fire safety applications.

Graphite Oxide Flame-Retardant Polymer Nanocomposites

Graphite oxide (GO) polymer nanocomposites were developed at 1, 5, and 10 wt % GO with polycarbonate (PC), acrylonitrile butadiene styrene, and high-impact polystyrene for the purpose of evaluating the flammability reduction and material properties of the resulting systems. The overall morphology and dispersion of GO within the polymer nanocomposites were studied by scanning electron microscopy and optical microscopy; GO was found to be well-dispersed throughout the matrix without the formation of large aggregates. Mechanical testing was performed using dynamic mechanical analysis to measure the storage modulus, which increased for all polymer systems with increased GO loading. Microscale oxygen consumption calorimetry revealed that the addition of GO reduced the total heat release and peak heat release rates in all systems, and GO-PC composites demonstrated very fast self-extinguishing times in vertical open flame tests, which are important to some regulatory fire safety applications.

Interaction of a phosphorus‐based FR, a nanoclay and PA6—Part 1: Interaction of FR and nanoclay

AbstractThe thermal decomposition of organophosphorus fire‐retardant (OP1311) and/ or organonanoclay (Cloisite 30B) is hereby investigated employing thermogravimetric analysis (TGA), to give an insight into their intrinsic behaviour and interaction in polymer nanocomposites for fire safety applications, because the addition of OP1311 and Cloisite 30B in Polyamide 6 (PA6) seems to have a synergistic effect on the thermal decomposition of PA6 (part 2 of the paper). An important objective of this research was to determine to what extent phosphorus components escape in the gaseous phase, which will affect the heat of combustion of the fire‐retarded polymer. The decomposition products arising from pyrolysis and combustion are investigated by means of Fourier transform infrared spectroscopy. Under pyrolytic conditions, the inclusion of Cloisite 30B into OP1311 (FR) shows a synergistic effect on the initial mass loss at low temperature of ∼280–420°C and leads to the acceleration of the thermal degradation process. While the DTG curve of Cloisite 30B shows two distinct degradation peaks (steps) that of OP1311 and OP1311 plus Cloisite 30B show four degradation steps. TGA measurements of OP1311 in nitrogen show more mass loss than in air, whereas Cloisite 30B gives similar amounts of mass loss in air and nitrogen. In nitrogen, the major evolved gaseous species from Cloisite 30B alone are hydrocarbons, 2‐(diethylamino)ethanol and water, whereas the evolved gases from that of OP1311 at ∼320°C are mainly water, at ∼420°C, carbon dioxide, water and ammonia and at 480–570°C diethylphosphinic acid. Under thermo‐oxidative conditions, the gases evolved are mainly carbon dioxide and water from both Cloisite 30B and OP1311. Copyright © 2009 John Wiley & Sons, Ltd.

The International FORUM of Fire Research Directors: A position paper on performance-based design for fire code applications

The International FORUM of Fire Research Directors (FORUM) periodically takes a position on a technical issue of international significance confronting the fire safety research community. The position of the FORUM on performance-based regulations, codes and design for fire safety applications, and the rationale leading to it, is described in this paper. Aspects addressed include current capabilities and challenges associated with the application of performance-based design, and possible enhancements (obtained through a coordinated and sustained global effort of research) in next generation tools leading to more certain predictions of the effects on performance of changes in building materials, active and passive fire protection systems, compartmentation, and egress systems; the structural response of a building to large fires including those leading to full building burnout; the impact of fire on neighboring buildings and infrastructure; and the uncertainty in deterministic predictions for incorporation into reliable probabilistic calculations of hazard and risk.

Review on Fire Safety Objectives and Application for Airport Terminals

Prior to proceeding with any design, fire safety strategies must be developed based on clearly defined goals. In this review paper, an example is provided for discussion of the special features of an airport terminal, the specific fire safety strategies employed, the utilization of the cabin design, and its defects. The use of a water-mist fire suppression system and a drencher system are recommended to the airport authority for improving the fire safety provisions.

Mitigation of CO2by Chemical Conversion: Plausible Chemical Reactions and Promising Products

A critical literature analysis was conducted on the viable usage of CO2 in the framework of the attempts to reduce the emissions of CO2 into the atmosphere from various processes or the rate of increase of the concentration of CO2 in the atmosphere. Applications based on the physical properties of CO2 are summarized first. Major examples are applications in supercritical extraction, enhanced oil recovery, and use as inert gas in fire extinguishing and safety application in industry. The various possibilities of use in chemical applications are systematically discussed. CO2 can react with several hydrocarbons and nitrogen-containing compounds (NH3, amines, imines). It can be used as a weak acid or as an oxidizing agent. It can be reduced electrochemically, photochemically, or chemically or by a syngas route. A variety of products can be manufactured from CO2, e.g., acids, alcohols, esters, lactones, carbamates, urethanes, urea derivatives, various copolymers, and polymers. In particular, polycarbonates are...

AFFF protection for weapons staging areas

U.S. Navy air-capable ships require the staging of weapons near superstructures, which results in a fire and explosion hazard to mission-critical flight operations areas. An aqueous film-forming foam (AFFF) fire suppression system was designed and tested which will rapidly control a flammable liquid-fuel spill fire in the weapons staging area. Factors which influenced the design of the system included limited available water and AFFF supply, severe wind conditions which dramatically change AFFF spray pattern coverage, and cooling requirements to prevent weapons explosions. The resulting fire suppression system utilizes AFFF discharged through non-air aspirating spray nozzles located near the weapons staging area deck. Data and results of testing may have other aviation fire safety applications.

An experimental study of droplet extinction in the absence of external convection

The flammability of combustible materials in a spacecraft is important for fire safety applications because the conditions in spacecraft environments differ from those on earth. Experimental testing in space is difficult and expensive. However, reducing buoyancy by decreasing ambient pressure is a possible approach to simulate on-earth the burning behavior inside spacecraft environments. The objective of this work is to determine that possibility by studying the effect of pressure on concurrent flame spread, and by comparison with microgravity data, observe up to what point low-pressure can be used to replicate flame spread characteristics observed in microgravity. Specifically, this work studies the effect of pressure and microgravity on upward/concurrent flame spread over 10 mm thick polymethyl methacrylate (PMMA) slabs. Experiments in normal gravity were conducted over pressures ranging between 100 and 40 kPa and a forced flow velocity of 200 mm/s. Microgravity experiments were conducted during NASA's Spacecraft Fire Experiment (Saffire II), on board the Cygnus spacecraft at 100 kPa with an air flow velocity of 200 mm/s. Results show that reductions of pressure slow down the flame spread over the PMMA surface approaching that in microgravity. The data is correlated in terms of a non-dimensional mixed convection analysis that describes the convective heat transferred from the flame to the solid, and the primary mechanism controlling the spread of the flame. The extrapolation of the correlation to low pressures predicts well the flame spread rate obtained in microgravity in the Saffire II experiments. Similar results were obtained by the authors with similar experiments with a thin composite cotton/fiberglass fabric (published elsewhere). Both results suggest that reduced pressure can be used to approximately replicate flame behavior of untested gravity conditions for the burning of thick and thin solids. This work could provide guidance for potential ground-based testing for fire safety design in spacecraft and space habitats.

Aerosols slowly making a comeback

The aerosol industry has had a lot to contend with over the past decade or so. Countless critics prepared its obituary after the formulation of the ozone-depletion theory by F. Sherwood Rowland and Mario J. Molina (see page 21), taking potshots at the ubiquitous but humble can, which had a market of nearly 3 billion units yearly. But the industry has confounded many of its critics, proving exaggerated the reports of its demise: Slowly, slowly, it is making a comeback, coping with legislation on environmental and safety grounds. New raw materials are contending for roles as propellants, both in traditional technology and new developments. And even the latest problem with which it has had to contend—the problem of flammability in large-volume storage—seems to be controllable. If industry studies are accurate, moreover, the designs for protecting against large-scale aerosol fires may prove more efficient, cost-effective systems for use in general fire-safety applications. Aerosols had ...