Metal Ammine Complexes: A New Class of Flame Retardants

Pitts, J. J.

doi:10.1177/0021955x7100700406

Cited by 9 publications

(5 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Pitts [1] had suggested that the production of a large amount of ammonia during the decomposition of ammonium compounds might act as a diluent in the flame. It has been reported [2] that certain metal ammine complexes like cobalt hexammine complex, which release large quantity of NH,, on decomposition act as flame retardants primarily through their action in the gas phase where the liberated NH3 acts as a diluent. But such complexes give metal salts or oxides also and the precise effect of these products are not reported.…”

mentioning

confidence: 99%

Note: Does Ammonia Act as a Flame Retardant?

Kishore

Mohandas

1983

Journal of Fire Sciences

View full text Add to dashboard Cite

Ammonium compounds are examples of classical fire retardants used in polymers and they are still in use particularly in cases where the chances of the additive getting leached out are less. The commonly used ammonium compounds are (NH.)2HP04, NH4H2P04, (NH4POa)n, (NH4)2S0., NH,Br, NH.CL etc. The main advantage of these compounds when used as fire retardants is that they readily decompose to give the inorganic acid by virtue of which the overall fire retardancy is achieved. However, during the thermal degradation of these additives, there is the liberation of considerable amounts of ammonia, which will escape into the flame phase during the burning of the system. The exact role of ammonia in the combustion of polymers is still not very clear. Pitts [1] had suggested that the production of a large amount of ammonia during the decomposition of ammonium compounds might act as a diluent in the flame. It has been reported [2] that certain metal ammine complexes like cobalt hexammine complex, which release large quantity of NH,, on decomposition act as flame retardants primarily through their action in the gas phase where the liberated NH3 acts as a diluent. But such complexes give metal salts or oxides also and the precise effect of these products are not reported. Recently, it has been shown that metal oxides desensitize the thermal degradation and ignition of polystyrene [3,4] and therefore the contribution of NHs in the total fire retardant effect of metal ammine complexes cannot be singled out without a thorough investigation.We conducted the burning rate measurements on polystyrene (PS) samples, burned in flowing oxygen atmosphere containing small amounts of ammonia. Though a very slight increase in the burning rate was noticed, it was not reproducible and the change was within the error involved in the experiment. Thus any chemical inhibition effect of NH, is improbable.In the above experiment, the ammonia was added to the oxidant side of the flame, unlike the actual case of burning of a polymer + additive system, wherein the ammonia is evolved from within the fuel. So, we designed a simple experiment in which the NHa is introduced on the fuel side of the flame. A schematic of the experiment is given in Fig. 1. NH3 was passed at a controlled rate through the hole drilled along the axis of the sample. The flow rate of NH3 (N 6 X 10-6

show abstract

mentioning

confidence: 99%

Note: Does Ammonia Act as a Flame Retardant?

Kishore

Mohandas

1983

Journal of Fire Sciences

View full text Add to dashboard Cite

show abstract

“…Cobalt ammines have been shown to be very good flame retardants for flexible polyurethane foams [137]. The results obtained with Co(NH3)6CI 3 could probably be ascribed to the fact that it breaks down in precisely the same temperature region as the polymer (Fig.…”

Section: Fig 1 Curing Study Of a Commercial Resinmentioning

confidence: 91%

DTA and DSC studies on polymers containing fire retardants

Bhatnagar¹,

Vergnaud²

1983

Journal of Thermal Analysis

View full text Add to dashboard Cite

This publication surveys the results obtained by means of thermal analysis particularly with DTA and DSC methods in the field of synthetic and natural polymers treated with various flame retardant additives.The 167 references citated cover the most important territories of the up to date problems.For several years, differential thermal analysis (DTA and DSC) have been widely used as a screening test and for quality control purposes. The most convenient method for studying polymer oxidation by DTA or DSC is to use the instrument in isothermal mode. Typically, thermal equilibrium is established with nitrogen flowing over the sample and the gas is then changed to oxygen or air.In the instruments, a Perkin-Elmer model DSC-2 Calorimeter and SETARAM-DSC III are well known. The capability of the DSC III for doing a gas sweeping of the sample allows the study of solid-gas reactions. The quantitative measurements obtained with different gases are reproducible and can be compared because the sensitivity of the calorimeter is not modified by the nature and the flow-rate of the gas.In the Perkin-Elmer Model DSC-2, the sample weighing between 1 and 20 mg is placed in an open pan in the DSC head, the sample cup closed with a perforated cover and the head closed. At this stage, Billingham et al, found that the temperature was 320 K and an oxygen flow of 30 ml min-1 was maintained in the head. The sample was heated to the required temperature at 320 K min-1 and the recorder and data logger started at the point where thermal equilibrium was indicated. There was a small thermal lag involved due to the sample melting, but this took less than 1 minute and they found this method easier than attempting to change the flowing gas, because of the long gas flow path of the DSC head.

show abstract

“…One of the possible reasons for the effectiveness of nitrogen compounds as combustion inhibitors is the liberation of nitrogen, which reduces the concentration of volatile decomposition products and restricts their flammability (92) . A very effective agent recommended for retarding the combustion of nitrogen containing polymers, particularly polyurethanes, is the organometal cobalt complex Co(NH 3 ) 6 Cl 3 , one mole of which during thermal decomposition releases almost 6 moles of volatile nonflammable products into the gaseous phase (89,93) :…”

Section: S Boryniec and W Przygockimentioning

confidence: 99%