A novel biomolecule and reactive flame retardant based on methionine for cotton fabrics.

A novel reactive flame retardant (FR) based on methionine containing P, N and S flame retardant elements was synthesized for application to cotton fabrics. It was found that the cotton fabrics finished with this flame retardant had excellent flame retardancy and high durability. The limiting oxygen index of the fabric treated with 29% methionine-based FR was as high as 43.9%, and was 37.7% after 50 laundering cycles. Thermogravimetry and thermogravimetry coupled with Fourier transform infrared spectroscopy (FTIR) tests showed that the flame retardant (FR) changed the cellulose decomposition pathway so that a large amount of residue was formed and only a small amount of combustible gases was generated. Scanning electron microscopy showed that the treated fibers were swollen, implying that the FR molecules entered the interior of the fibers, while X-ray diffraction results suggested that the FR have little effect on the cellulose structure. FTIR and X-ray photoelectron spectroscopy results demonstrated that the methionine-based FR contains P, N and S elements, the FR and cellulose formed stable P(= O)–O–C and –COOC– covalent bonds, while microscale combustion calorimetry experiments showed that the total heat release of the treated cotton fibers decreased considerably and the tensile strength of the finished cotton fabrics decreased slightly relative to those of the raw cotton. The free formaldehyde content of the treated cotton was tested, and the results showed that no free formaldehyde was detected in the treated cotton. These results show that the methionine-based FR is a highly effective biologically-based and durable flame retardant. [ABSTRACT FROM AUTHOR]