Modification of hedgehog-like structured carbon nanohorns to promote flame retardant synergistic effect in assembled coatings for protective cotton fabrics

Abstract

Considering the limitations of traditional halogen flame retardants to cotton fabrics, the modification of hedgehog-like structured carbon nanohorns was firstly proposed to improve flame retardant synergistic effect in assembled coatings for protective cotton fabrics. The assembled coatings containing 3-aminopropyl triethoxysilane (APTES), modified single-walled carbon nanohorns (SWCNHs-o) and ammonium polyphosphate (APP) endowed cotton fabrics with highly efficient flame retardancy at an ultralow spraying number of 4, which was much more favorable than other previously reported coatings. (APTES/SWCNHs-o/APP)4 effortlessly passed the vertical burning test and was capable of self-extinguishing. Furthermore, the LOI test showed that its LOI value could reach 29.0 ± 0.1%, suggesting a low fire exposure risk. Additionally, the results of cone calorimeter test displayed that pHRR, THR, MARHE and Av-EHC values of (APTES/SWCNHs-o/APP)4 significantly reduced by 93%, 57%, 89% and 98%, respectively. The morphology of its residual char remained complete, demonstrating that the P/N/Si heterocyclic char layer formed by SWCNHs-o and APTES in synergy with phosphorus provided a physical barrier to prevent the release of volatile combustibles and the transfer of oxygen and heat. This work provides an efficient and novel method for the design and fabrication of self-extinguishing intumescent coatings.