The Thermal Properties of Nitrocellulose: From Thermal Decomposition to Thermal Explosion

ABSTRACT

Nitrocellulose is an extremely dangerous explosive substance, which will decompose at a relatively low temperature. This article studied the thermal properties transformed from thermal decomposition to thermal explosion for a less violent nitrocellulose sample (nitrogen content: 10.92%). Four experiments were implemented: XPS analysis and SEM analysis, DSC-TG analysis, and small-scale thermal explosion experiment. From XPS analysis and SEM analysis, high temperatures led to the decrease of N1s and O1s (O-NO2 bond) and the break or even “melt” of the nitrocellulose fibers. The results demonstrated that nitrocellulose would become more unstable if it was exposed to high temperature. From the DSC-TG analysis and small-scale thermal explosion experiment, the upper critical ambient temperatures (UCATs) of the nitrocellulose were calculated. The UCATs of the nitrocellulose sample would decrease from 132.5ºC to 96.4ºC with the dimensions increased from 0.1 m to 1.6 m. The results demonstrated that the risk of spontaneous combustion and thermal explosion increased significantly with the increase of the volume of nitrocellulose.

KEYWORDS:

• Frank-Kamenetskii
• Nitrocellulose
• Thermal decomposition
• Thermal explosion
• Upper Critical Ambient Temperatures (UCATs)

Acknowledgments

This work was supported by International Program for Ph.D. Candidates of Sun Yat-Sen University. The authors wish to express thier appreciation for the support from the University of Wollongong.

Nomenclature

	=	frequency factor or pre-exponential factor
	=	reaction activation energy (J/mol)
	=	model function of solid-state reaction
	=	or characteristic dimension (m)
	=	reaction heat (J/mol)
	=	universal gas constant (8.314 J/(molK))
	=	temperature (of materials) (K)
	=	ambient temperature (K)
	=	critical ambient temperature (CAT) (K)
	=	volume (m)
	=	extent of reaction (mass fraction that has decomposed) (%)
	=	heating rate (ºC/min)
	=	Frank–Kamenetskii parameter
	=	critical Frank–Kamenetskii parameter
	=	thermal conductivity (W/(mK))

Additional information

Funding

Funding for this work was provided by Guangdong Provincial Scientific and Technological Project (No. 2013B090800008 and 2014B030301034) and ShenZhen Scientific and Technological Innovation Committee (No. JCYJ20130401161052963).