STUDY OF THE SUPRAMOLECULAR STRUCTURE INFLUENCE ON HYDROCARBONS FIRE HAZARD PARAMETERS

Abstract

A theoretical study of the supramolecular structure influence on the hydrocarbons
fire hazard parameters formation was conducted. The work aim is to develop a mechanism
for modeling possible supramolecular structures in a flame and to demonstrate the such an
approach efficiency for calculating fire hazard parameters. The characteristic temperatures
pulsation in homologous series due to differences in molecules clustering mechanisms were
chosen as supramolecular state features indicators. It is shown that flash and autoignition
temperatures have a change pulsation in the n-alkanes homologous series, which is similar
to changes in melting points and solubility in water. An assumption is made about the
clustering primary stage presence by the peroxide mechanism during the flame combustion
occurrence with the formation of an oxygen bridge between molecules, which is similar to
solubility in water. It is shown that fire hazard parameters can depend both on the smallest
cluster length and on the associated oxygen molecules number during the combustion
initiation. The n-alkanes aggregation proportions into clusters with the oxygen molecules
participation have been determined, which allow us to describe the critical conditions for
the combustion initiation with the sufficient convergence: lower and upper flammability
limits, lower and upper detonation limits, the stoichiometric concentration, the cold flame
upper limit. A formula was developed for the n-alkanes autoignition temperatures
predicting based on the "ease of melting" indicator, which works with R=0.98. It is shown
that supramolecular peroxide structures formed during the combustion initiation have
easier conditions for the condensation. It is calculated that the expected corresponding
characteristic temperatures of peroxide clusters phase transitions can be realized in a
flame. The condensation processes participation during combustion determines the flame
front minimum thickness for the single peroxide-polymer structure formation.