Application of a novel plasma-based method of introducing maleic acid and pentaerythritol phosphate urea salt onto polyester fabrics for durable flame-retardant treatment

In this work, a novel anti-flame poly(ethylene terephthalate) (PET) fabric was successfully fabricated by plasma-based technology combined with pad-dry-cure treatment finishing. Low-temperature plasma can graft maleic acid (MA) onto a PET polymer backbone, which can activate the PET fiber and provide the opportunity of reaction with pentaerythritol phosphate urea salt (PEPAS) to achieve an excellent and durable anti-flame ability. Furthermore, the chemical reaction between PET-MA and PEPAS can form a complex and compact net structure that can effectively improve the anti-dripping property of PET. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy analysis showed that MA and PEPAS were successfully introduced onto the surface of the PET fabric, and a compact protective carbon layer was formed during the combustion process due to the synergistic effect of phosphorus and nitrogen. The flame-retardant and anti-dripping properties were evaluated by thermogravimetric analysis, the limiting oxygen index (LOI) and a vertical burning test. The treated samples showed the maximum LOI value of 29.3, possessing excellent thermal stability and self-extinguishing ability and inhibiting melt-dripping ability. Moreover, tensile strength at break of the treated PET fabric was slightly greater than that of the original PET fabric, indicating that this type of treatment had little negative impact on the bulk of the PET fabric. After 20 laundering cycles, the LOI value of the treated sample still remained at 26.8, which indicated durability in the flame-retarding effect.