Comparison of multi‐component and mono‐component intumescent flame retardants for thermoplastic polyurethane composites

Conventional intumescent flame retardant (IFR) is comprised of multiple components (acid, carbon, and gas source). In comparison, “all‐in‐one” design of mono‐component IFR is effective to impart the homogeneity to functional sources in polymer matrix, which is significant to improve the synergy against combustion. In this work, a core‐shell structured mono‐component IFR (MAPP@FDS) are prepared with ammonium polyphosphate (APP) and furfural‐derived Schiff base (FDS) and applied to modification of thermoplastic polyurethane (TPU). TPU composite with the as‐prepared mono‐component IFR (TPU/MAPP@FDS) exhibits V‐0 rating in UL‐94 test and a limiting oxygen index (LOI) value of 32.0%, with prominent bulkiness of carbonaceous layer. Cone calorimetry tests (CCTs) showed a significant reduction in total heat release (THR) and peak heat release rate (pHRR) for TPU/MAPP@FDS compared with the TPU composites with multi‐component IFR. By analyzing the morphology and composition of residual char, the flame‐retardant mechanism of TPU/MAPP@FDS is reasonably proposed. This work illustrates the superiority of the integration to prepare mono‐component IFR and provides a potential method in developing TPU composites with remarkable flame retardancy. Highlights TPU/MAPP@FDS achieves a LOI value of 32.0% and UL‐94 V‐0 rating. TPU/MAPP@FDS exhibits significantly enhanced flame retardancy compared with TPU composites incorporated multi‐component IFR. The synergy in multi‐component IFR is prominently strengthened. A core‐shell structured mono‐component intumescent flame retardant (IFR) are prepared with ammonium polyphosphate (APP), silane coupling agent (APTES), and furfural‐derived Schiff base (FDS) and applied to modification of thermoplastic polyurethane (TPU). The “all‐in‐one” structure induces a deeper level of phosphorylation and char formation for IFR, enhancing synergistic effects in TPU composites to suppress combustion.