Investigation Of Effects Of Alum And Potassium Sesquicarbonate On The Fire Characteristics Of Flexible Polyurethane Foam

Numbers of observations are made in Fig. 12:

It can be seen that the temperature is constant both for treated and untreated samples.

1. The introduction of FRS dramatically delayed the onset of degradation.

2. This delay effect is more with potassium sesquicarbonate than potash alum.

It can be seen in Fig. 14a that;

(2) The presence of Alum FR slightly raised the start - temperature viz-a-vis that of the untreated sample. (3) As for the mid and final temperatures, there's hardly any observable differences that is that once degradation has started, these temperatures are not affected by the presence or the concentrations of Alum as FR.

The observations in Fig. 16 are rather conflicting in that whereas Alum FR increased the duration of thermal degradation for all the concentrations used, the case of potash is not clear - cut. In fact, it is only at 0.1 and 0.3 pph concentrations that the presence of potash enhance the times of thermal degradation. For other concentrations, the effect is minimal, if anything. Thermal degradation of materials requires energy supply for the breakage of bonds. This process known as pyrolysis is facilitated by conditions where energy is readily available. Thus it was expedient to monitor the changes in energy requirement with FR concentrations, Fig. 17a - Fig. 18b, it can be said from the observations in these figures that generally the presence of the FRS Alum and potash necessitated higher energy demands for pyrolysis / degradation to take place.

K2SO4.Al2(SO4)3.24H2O    K2SO4 + AL2O3 + SO3 + 24H2O

The products of this decomposition process affect the degree of flammability of the pyrolytic products. For example, both SO3 and H2O reduce the effective concentration of O2 in the system water also has a cooling effect. Al2O3 on the other hand forms an impervious layer on the substrate and, as it were suppresses the egress of flammable pyrolysates. Thus Alum acts as a FR by the solid - and vapour phase mechanisms. Potash or Akanwu or potassium sesquicarbonate, K2CO3.2KHCO3. 3/2 H2O), has not been featured as a FR but a cursory look at the chemistry of its decomposition at high temperature would indicate that it has the potential to act as one especially by the vapour and condensed phase mechanism.

K2CO3 . 2KHCO3.3/2 H2O  D         2K2O + 3CO2 + 3/2 H2O.

Thus CO2 and H2O dilute the concentrations of oxygen and flammable pyrolysates while K2O acts in the condensed phase to suppress flame propagation. It must however be stated that the effects of Alum and potash reported here are effective though not overly dramatic either because of the concentrations used or more likely because the substrate itself, polyurethane as a material is inherently flame retardant. Nitrogen - containing compounds such as urea's, amides, guanidine's etc. are used as flame retardant [17], by a mechanism that proceeds via the formation of N - containing acids.