Plasma‐assisted incorporation of flame‐retardant chemicals for improved flame retardancy of polyester fabrics

Abstract The polyester fabric was subjected to atmospheric plasma and impregnated with commercially available 3‐hydroxyphenyl phosphinyl‐propanoic acid (3HPP) as flame retarding agent by high‐temperature high pressure (HTHP) dyeing method. Various concentrations of 3HPP in water, up to 4% w/v, were applied using the HTHP method. It was observed that the plasma treatment not only enhanced wettability and wicking but also facilitated increased pickup of 3HPP onto the polyester. The treatment exhibited a noteworthy enhancement in the limiting oxygen index (LOI), rising from 20.8% for the untreated control fabric to 30% for the fabric treated with plasma and a 4% 3HPP solution. Additionally, the application of 3HPP without plasma treatment did not yield significant improvements in flame‐retardant (FR) properties. The combined treatment of plasma and 3HPP resulted in an LOI of 29% with a 2% 3HPP treatment, while at the same concentration without plasma treatment, the LOI value was 26.8%. The heightened LOI was primarily attributed to the presence of phosphorus, as confirmed by high‐performance liquid chromatography and energy‐dispersive X‐ray spectroscopy. Additionally, the wash durability assessment of plasma‐processed and 3HPP‐treated samples demonstrated sustained flame retardancy, with an LOI of approximately 28% even after undergoing 20 wash cycles. Vertical flammability and cone calorimetry also confirm improved FR properties after treatment. Remarkably, the mechanical properties and surface morphology of the fabric remained unaltered following both plasma and chemical treatments. Highlights Easy and cost‐effective technique for the downstream process for FR polyester fabric. FR agent during polymerization has the disadvantage of lower molecular weight. Potential for producing FR industrial polyester fabric. Post‐plasma treatment improves the washing fastness. The mechanical and comfort properties remain intact during the process.