N-substituted cyclic phosphoramides as flame-retardant and anti-dripping coatings for PET fabric

Abstract

Fabric made of polyethylene terephthalate (PET) is a common textile that is widely used in daily life. Its flame retardancy has emerged as a major concern for lowering the risk of fire. As a kind of popular flame retardants, cyclic phosphoramides have been widely applied to improve the flame retardancy of various inflammable materials. To achieve more suitable and effective flame retardants for PET fabric, the fire-safety capabilities of PET fabric coated with various cyclic phosphoramides substituted by siloxane (PDPTP), hydroxyphenyl (DPHBP), and hydroxyethyl (PDNP) groups was explored in this work. All of these chemicals can successfully prevent PET fabric from melting and burning, providing it good flame retardancy and non-dripping performance. LOI values for PET fabrics coated with PDPTP, DPHBP and PDNP increased to 24.6, 25.2, and 30.3% under comparison loadings. These flame-retardant coatings enhanced the char-forming capacity for PET fabric. The residues at 700 °C increased to 26.5 and 27.4% for PDPTP and PDNP coated fabric in N2 atmosphere compared with 2.9% for pure fabric. Peak heat release rate (PHRR) and total heat release (THR) was effectively restrained by 50% and 35%, respectively. Fortunately, these flame-retardant coatings had no detrimental effects on the mechanical characteristics of PET fabric and even enhanced the weft's tensile breaking forces. Apart from DPHBP significantly reducing the fabric's whiteness, the whiteness of PDPTP and PDNP coated PET fabric hardly changed. The effect of cyclic phosphoramides with various substitutions on the flame retardancy of PET fabric is thoroughly discussed in this paper, which might be useful in the development of more effective flame retardants for PET materials.