Construction of a sustainable, reactive and phytate-based intumescent flame-retardant for silk textile

The exploitation of plant-derived phytic acid as effective and durable flame retardant (FR) for textiles is of great significance for developing novel and ecological functional textile products. In the present study, a reactive and phytate-based FR namely pentaerythritol phytate ethylenediaminetetraacetic ester (PPEDTE) prepared by the esterification of phytic acid, pentaerythritol and ethylenediaminetetraacetic acid was investigated as intumes-cent FR agent for silk fabric. The chemical structure of PPEDTE and its potential grafting mechanism on silk were studied. The thermal stability, heat and smoke suppression property, flame retardancy and washing resistance on silk fabric were studied. The deposition and covalently cross-linked PPEDTE on silk fabric enabled it to self -extinguish in vertical burning test. The coated silk fabric with an add-on of higher than 10.7% could with-stand 15 washing cycles, displaying good washing durability. The intumescent FR coating remarkably decreased the release of heat and smoke of silk during burning. The coated silk had high thermal stability and left sig-nificant combustion residues after the burning tests. These results demonstrate that the synthesized PPEDTE warrant potential as efficient and reactive intumescent FR approach for silk.