Experimental Study on the Fire Properties of Nitrocellulose with Different Structures

Abstract

In order to ensure the safety of inflammable and explosive chemical substance such as nitrocellulose (NC) mixtures in the process of handing, storage, and usage, it is necessary to obtain the fire properties of NC with different exterior structures. In present study, fire properties of two commonly used nitrocelluloses with soft fiber structure and white chip structure were investigated by scanning electron microscope (SEM) and the ISO 5660 cone calorimeter. Experimental findings revealed that the most important fire properties such as ignition time, mass loss rate and ash content exhibited significant differences between the two structures of NC. Compared with the soft fiber NC, chip NC possesses a lower fire hazard, and its heat release rate intensity (HRRI) is mainly affected by the sample mass. In addition, oxygen consumption (OC) calorimetry method was compared with thermal chemistry (TC) method based on stoichiometry for HRRI calculation. HRRI results of NC with two structures obtained by these two methods showed a good consistency.

Effect of Bulk Density on the Combustion Property of Nitrocellulose with Isopropanol Humectant

“…For the similar NC-isopropanol mixtures burned in Refs. [11,20], the overall regression rate is relatively lower than that in this work, as shown in Figure 6. This is probably because the NC-isopropanol mixtures in their experiments were burned in a shallow cuboid ceramic crucible with an open rectangular area of 1000 mm 2 and depth of 13 mm, which is quite different from the usually used steel burner.…”

“…Relevant research concerning the combustion behaviors of NC-alcohol humectants can also be found in recent literature [11,20], while limited amount of samples was burned for the tests, i. e. the maximum weight is only 2 g. No relatively stable burning stage can be observed from these experiments, and all of burning rates exhibit prominent parabolic variation. Thus, for the convenience of comparison, the overall regression rate over the whole combustion duration is roughly calculated as…”

“…The researches above aim to understand the combustion behaviors of pure NC, while for more practical situations, examinations on the fire properties of NC-humectant mixtures are also of great necessity. Recently, the combustion behaviors of NC-alcohol and -plasticizer mixtures were also investigated by means of a cone calorimeter (ISO 5660) [11,20]. However, the fire loads in their experiments were quite limited, with the maximum sample weight of 2 g, and all the tests maintained the similar bulk density.…”

A Simplified Method to Predict the Heat Release Rate of Industrial Nitrocellulose Materials

“…Other fire behaviors of NC samples are also measured and discussed. Three NC samples identical to that in [25,26] are adopted to perform the current experiments.…”

“…The effects of pressure and initial fuel temperature on the burning rate of NC-based propellants were also experimentally examined by previous researchers [23,24]. Recently, He and Wei et al [25,26] attempted to employ ISO 5660 to investigate the combustion properties of NC-alcohol humectant and -dibutyl phthalate (DBP) plasticizer mixtures. The amount of sample used in their tests are quite small, i.e., 1 g and 2 g, filled in a crucible with rectangular area of 10 cm 2 , which is relatively marginal for evaluating the heat release rate (HRR) of NC.…”