Study On The Characteristics Of Combustion Residues Of Typical Combustibles

It brings great difficulties to the post-fire identification and investigation due to various causes,complicated process and is greatly affected by environment and social activities.The emphasis of fire investigation is to find and extract the effective material evidence to determine the ignition point and other important information for further study on the cause and the whole process.Therefore,the accurate collection and effective analysis of combustion residues would be the most important task in the post-disaster investigation,which is of great significance for the definition of fire accidents,as well as new methods and ideas for the similar accidents.In order to explore the characteristics of combustion process and residues of typical combustible,paulownia,polypropylene,and cotton cloth were used as combustible and ethanol,diesel,and gasoline were used as accelerant.The experiments were designed to analyze the characteristics of the combustion residue under different conditions.The X-ray Photoelectron Spectroscopy(XPS),Raman spectroscopy(Raman)and Transmission electron microscopy(TEM)were mainly conducted to text and analyze combustion residue samples.The combustion residues can be obtained through the the combustion of paulownia board,paulownia board soaked in 5 ml ethanol and diesel oil respectively.Samples were collected for test and analysis at characteristic locations in the residues.The kind of functional groups is the same in each residue samples,but their relative contents are different.The combustion improver can be distinguished by the content characteristics of each functional group.The results of C/O and ID/IG value obtained by XPS and Raman test respectively show that the highest oxidation degree of combustible is at the edge of the combustion residue.The information was obtained by TEM,such as particle morphology,carbon chain length,particle size and others,indicate that the addition of combustion improver has a certain influence on the oxidation degree of wood board combustion.Diesel and ethanol were used as accelerant,and polypropylene plate was used as combustible.The results show that the addition of accelerant makes polypropylene more flammable and the rate is faster.There is a positive relationship between addition amount of ethanol and combustion rate.The same functional groups exist in the polypropylene combustion residue at the same position,but in different burning time.However,the different content of the functional groups can determine the combustion time to some extent.In order to investigate the characteristics of combustion residues of different types of fuel,ethanol,gasoline and diesel and their mixture were burned and the residues were extracted for characteristic analysis.There is almost no trace after ethanol combustion,while diesel has black trace and gasoline has the yellow trace.The oxidation degree of mixture residual is higher than that of only one fuel.The fuel type can be determined by the content of functional groups and the particle size and particle arrangement in the sample.Five typical combustibles were selected to detect and analyze the residues before and after adding gasoline,in order to research the influence of gasoline on combustible combustion residues.The results show that the combustion residue sample added with gasoline is different from the unadded one through SEM analysis.The XPS results show that the type of combustibles can be preliminarily determined by the type and content of characteristic functional groups,and whether gasoline is added to the reaction or not.-It can be concluded that gasoline has the most obvious aggravating effect on the oxidation reaction of paulownia boards through XPS and Raman analysis.