Preparation of Flame Retardant Polyacrylonitrile Fabric Based on Sol-Gel and Layer-by-Layer Assembly

Abstract

This paper aims to develop a novel method, i.e., sol-gel combined with layer-by-layer assembly technology, to impart flame retardancy on polyacrylonitrile (PAN) fabrics. Silica-sol was synthesized via the sol-gel process and acted as cationic solution, and phytic acid (PA) was used as the anionic medium. Flame-retardant-treated PAN fabric (FR-PAN) could achieve excellent flame retardancy with 10 bilayer (10BL) coating through layer-by-layer assembly. The structure of the fabrics was characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The thermal stability and flame retardancy were evaluated by thermogravimetric (TG) analysis, cone calorimetry (CC) and limiting oxygen index (LOI). The LOI value of the coated fabric was up to 33.2 vol % and the char residue at 800 °C also increased to 57 wt %. Cone calorimetry tests revealed that, compared to the control fabric, the peak of heat release rate (PHRR) and total heat release (THR) of FR-PAN decreased by 66% and 73%, respectively. These results indicated that sol-gel combined with layer-by-layer assembly technique could impart PAN fabric with satisfactory flame-retardant properties, showing an efficient flame retardant strategy for PAN fabric.

Surface Functionalization of Cotton and PC Fabrics Using SiO2 and ZnO Nanoparticles for Durable Flame Retardant Properties

“…The sol-gel process has been extensively studied in recent years for flame-retardants [24][25][26][27]. Synthesis is based on two-step reactions, i.e., hydrolysis (converted to unstable hydroxides) and condensation (formation of covalent bonds) of a metal-organic precursor such as an alkoxide, tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), and titanium tetraisopropoxide (TTIPO) [28,29].…”

Polyvinyl Alcohol Reinforced Flame-Retardant Polyacrylonitrile Composite Fiber Prepared by Boric Acid Cross-Linking and Phosphorylation

“…The chemical compositions of PAN, PVA/PAN, C-PVA/PAN, and FR-PVA/PAN were analyzed by XPS, as shown in Figure 2 and Table 2. The four samples all contained C 1s , N 1s , and O 1s , corresponding to the peaks at 300 eV, 409 eV, and 543 eV, respectively [11,12,13]. Compared with PAN fiber, the PVA/PAN fiber showed an increase of the oxygen element from 10.86% to 14.28%.…”

“…In the case of the C-PVA/PAN fiber, the peak at 191 eV was assigned to B 1s [20]. For FR-PVA/PAN, a new peak at 131 eV, assigned to P 2p [11,12,13], clearly appeared. Thus, it can be concluded that the chemical modification of C-PVA/PAN with phosphoric acid was successful.…”

“…The fire growth rate index (FIGRA) was a deduced parameter which equals the ratio of PHRR and time to PHRR and reflects the maximal fire hazard when a material is under real burning conditions [29]. The FIGRA value of the FR-PVA/PAN fiber decreases by 67.4%, demonstrating the suppression for both the fire occurrence and the fire spread [11].…”

“…Moreover, the yellow or brown color of the fiber restricts its broad application. To overcome the mentioned drawbacks, we used hydroxylamine hydrochloride to react with a PAN fabric, followed by phosphorylation to obtain a durable flame-retardant PAN fabric [11]. The LOI value is 29.8% after 20 cycles of washing, which shows a good durable flame-retardant performance.…”