Investigation on the inhibition dynamic mechanism of short carbon chain fluoride foam on the coal spontaneous combustion

Coal is an important strategic resource and the coal spontaneous combustion threatens the personnel health and ecological safety. The objective of the present paper is to propose a novel APG fluoride foam to enhance the molecular stability and inhibition capability by introducing the alkyl polyglycolide (APG) and low-carbon chain perfluoro-(4-methyl-2-pentene) (C6F12). Research indicates that SDS head group shortens to 1.58 & Aring; and tail chain elongates to 14.13 & Aring; in the APG fluoride foam. The APG tail chain hydrogen exerts a stronger attraction to fluorine in C6F12. The -C7H7O, -C8H9, -CH3, and -OH react with C6F12 to form stable compounds. The -CH3 reaction creates the lower activation energy and heat release, calculated at 170.62 kJ/mol and -41.98 kJ/mol. The AFF film thickness is 51.75 mu m and experiences a slow expansion progress at 1.0-9.0 min. The AFF coal creates a higher crossing-point temperature at 175.8 degrees C and a full-course heating rate at 1.084 degrees C/min. The AFF coal makes 26.21 % decreasing amplitude on the -CH3 functional group relative to the OF coal. The APG fluoride foam provides the superior foam stability and stronger inhibition capacity on the coal spontaneous combustion.