Insight into pyrolysis degradation of polyester/cotton blended fabric with a system of two-component independent flame-retardation by Py-GC/MS analysis

Abstract

Pyrolysis degradation of polyester/cotton (Terylene/cotton T/C) blended fabric is complex because the interaction of individual components generates more flammable volatiles and burns more intensely. Having previously reported a two-component independent flame-retardant (TIF) system of flame-retarding T/C blended fabric to inhibit the “scaffolding effect”, in which the polyester component was copolymerized of phosphorus containing flame retardant monomers and the cotton component was finished by grating vinyl ammonium phosphate (AMVP) (Xie et al. Polymer Degradation and Stability, 2024, 220, 110638). However, how these treatments influence the interaction between the cotton and polyester components during pyrolysis, the mechanisms behind flame retardancy remains unclear. Here a thorough study of the pyrolysis degradation of cotton, polyester, and T/C blended fabric with or without treatment using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) to identify the detailed pyrolysis products, allowing depicting the interactions of two components and the flame-retardant (FR) mechanism. The pyrolysis results of the TIF system show that the composition of pyrolysis products had changed compared to the commercial single FR finishing blended fabrics. The present of high benzoic acid/acetaldehyde ratio (2.85) demonstrated that the TIF system was inhibiting pyrolysis interference between the polyester and cotton components, in which independently charring and flame retardant, forming char barrier layers. Additionally, a high P-containing compounds (1.61 %) provided an explanation for the lower flammability. This work will shed light on the forthcoming research of FR mechanism for the new component independent FR blended fabrics.