An overview of fire retardant treatments for synthetic textiles: From traditional approaches to recent applications

Synthetic textiles make a great contribution as the apparel, industrial and technical textile goods, though most of them are inherently flammable. Thus, the fire retardant treatment of synthetic textile materials always puts a huge significance to deal with; meanwhile the art of flame retardant application is taking a new shape globally considering the modification of the textile surfaces as well as the structure of applied flame retardant compounds. Thus, this review depicts the fire retardant treatment of some common synthetic textiles like polyamide 66 (PA66), polyamide 6 (PA6), polyethylene terephthalate (PET) and polyacrylonitrile (PAN) etc. focusing on the traditional approaches as well as the recent practices. In addition, this article aims to be established as a kind of general review that summarizes all relevant works carried out till the date with a view to realize the growing trend of this field in terms of applied compounds and application techniques and try to discover their impacts on anti-dripping, fire and thermal behaviors. In this review, it is seen that the very common drawbacks of most of the synthetic textiles are the melt-dripping and limited charring. Thus, to overcome these phenomena, in many instances, researchers adopt the surface modification technique prior to the final finishing in attaining the fire retardant behaviors. This kind of surface engineering usually using some epoxidized and acyrated aliphatic chains surely modifies the flame retardant and combustion behaviors where some improvements in the reduction of the peak heat release rate (pHRR) and a significant increase in char yield% are realized. In addition, this kind of modification also seems to be much effective in stopping the melt-dripping phenomenon of synthetic textiles. In parallel, it is noticed that the researchers also take initiative to modify the chemical structure of applied flame retardant compounds; especially they do incorporate several flame retardant elements like phosphorus (P), nitrogen (N), silicon (Si) and boron (B) etc. in a single structure to intensify the fire retardant efficacy of the same. For example, some of these compounds are effective both in the condensed and gas phase flame retardant mechanism or in some cases, some structures can enhance the limited charring of synthetic textile materials or can provide thermal stability of these char residues via providing a physical barrier effect due to their synergistic involvement in a typical flame retardant system and thus, an optimum level of flame retardancy are realized for the treated textiles. So, it is thus indispensable to realize the physio-chemical interactions between the polymeric structures (i.e., textiles) and the applied flame retardant compounds to design the future fire retardant treatment through selecting a right compound and an appropriate application method for a typical textile material. From this point of view, this review is a significant work to focus on some key flame retardant and combustion parameters like limiting oxygen index (LOI) values, vertical burning test (VBT) and peak heat release rate (pHRR) data along with an exploration of the flame retardant mechanism and durability issues of such applications.