A novel phosphoryl imidazolate flame retardant for polyester-cotton blend fabrics: Flame retardancy, thermal behavior and mechanical properties

Abstract

Inspired by the disperse dye in thermosol dyeing for polyester and polyester- containing fabrics, a novel small-molecule phosphoryl imidazolate compound with phosphorus, nitrogen, and heterocyclic aromatic structure, 2-(1H-imidazol-1-yl)-5,5-dimethyl-1,3,2-dioxaphosphinane-2-oxide (DOPIM), was successfully synthesized and utilized to enhance the flame retardancy of polyester-cotton blend (PTCO) fabrics through a convenient dip-dry-cure (PDC) strategy. The FTIR and NMR were employed to detect the chemical structure of DOPIM. Furthermore, to investigate the enhancement of PTCO's flame retardancy by integration of DOPIM, the thermal stability, flammability, combustion behavior and physical properties of the samples were comprehensively assessed. The char residues of the treated PTCO in the nitrogen atmosphere increased to 12.86 % from 2.90 % of the PTCO at 700 °C. The DOPIM treated PTCO exhibited a LOI of 28.7 % and exceptional self-extinguishing performance, with a damage length of 36 mm. The PHRR and THR of the DOPIM-treated PTCO decreased by 33 % and 32 %. TG, CCT and TG-FTIR analysis of PTCO, along with other test results demonstrated that DOPIM not only facilitated the degradation and char formation of cotton fibers, reducing their flammability, but also significantly reduced the degradation rate of polyester fibers. The presence of char and nonflammable gases generated from both the cotton and DOPIM contributed to form a stable char in PTCO. This indicates that DOPIM effectively worked for both cotton and polyester, enhancing the overall fire resistance of the PTCO. Notably, the DOPIM had no significant negative effect on the mechanical properties, handle and whiteness of the PTCO. In summary, this work offered a convenient and effective method for fabricated fire-safety PTCO, which holds significant importance in safeguarding life and property.