Combustion or burning is an oxidation process in gaseous phase which requires fuel, oxygen and heat sources. The burning phenomenon continues till the complete depletion of at least one of the sources. Thus, the flame retardancy can be achieved through omitting at least one of the sources. With the development of nano-technology and also commercial products made of nanofibers during the last decade, their responses against heat and flame are of great importance. Since the polyacrylonitrile (PAN) nano-fibers are being used broadly in various industries, an attempt was made herein to study their behavior against the flame and heat. Various important parameters including the nano-fiber production technique (conventional and core-shell) and the types of additives (nano-clay, carbon nano-tube, silicone coating) were considered. SDL, Simultaneous Thermal Analysis (STA) and Limited Oxygen Index (LOI) testing machines were exploited to eva‎luate the flammability behavior of nanofibers. The flammability of nanofibers were examined with SDL testing machine in accordance with ASTM D1230. Based on the findings, the core-shell nano-fibers exhibited higher flammability over the conventional one which is resulted by the higher porosity, while conventional ones showed only shrinkage. Moreover, the addition of retardants with high weight percentage resulted in bulkier structure with higher porosity, which reduced the flammability resistance of the nano-fiber, since the induced bulkier structure dominated over the effect of retardancy provided by the flame retardants. According to STA results, the effect of retardancy dominated over the bulk structure of nano-fibers for temperatures below the 600 ℃, which increased the thermal stability of the fibers. Since the temperature of the tip of the flame is around 1000 ℃ in SDL, the flammability behavior of nanofibers are eva‎luated in higher temperatures. Thus, STA testing machine provides more accurate results. On the other hand, based on the findings and considering the unavoidable error of testing machine, the LOI testing machine is not an appropriate technique to study the flammability behavior of nanofibers.

عبدالكريم حسيني، داريوش سمناني

محمدعلي الشريف

اكبر خدامي، صديقه برهاني