RBC agglutination was determined by the number of protonated amine groups on chitosan and its derivatives.

A rigid polyurethane foam (RPUF) composite was prepared by compounding phytic acid (PA)-functionalized Graphite oxide (PA-GO) with flame-retardant poly (Ammonium phosphate) (APP) and expandable graphite (EG). The effects of PA-GO on the thermal, flame-retardant, and mechanical properties of RPUF were studied using a thermogravimetric analyzer, a limiting oxygen index (LOI) tester, a UL-94 vertical combustion tester, a cone calorimeter, scanning electron microscopy, and a universal tensile testing machine. The results indicated that there was a significant synergistic flame-retardant effect between PA-GO and the intumescent flame retardants (IFR) in the RPUF matrix. Compared with RPUF-1, the addition of 0.3 wt% PA-GO could increase LOI from 25.7% to 26.5%, increase UL-94 rating from V-2 to V-0, and reduce the peak heat release rate (PHRR) and total heat release rate (THR) by 28.5% and 22.2%, respectively. Moreover, the amount of residual char increased from 22.2 wt% to 24.6 wt%, and the char layer was continuous and dense, with almost no holes. Meanwhile, the loss of mechanical properties was apparently lightened.

Organic modified kaolinite-urea intercalation complex (KUIC) was prepared using dimethyl sulfoxide (DMSO) as the precursor of kaolinite intercalation. Its structure was characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD). Subsequently, as a synergistic agent, KUIC was combined with flame retardant ammonium polyphosphate (APP) to improve the flame retardant and smoke suppression performance of unsaturated polyester (UP) resin. A cone calorimeter (CONE) was used to study its flame retardancy and smoke suppression, and a scanning electron microscope (SEM) and thermogravimetry (TG) were used to study the micro morphology of the char and flame retardant mechanism. The results show that 12 phr of APP and 3 phr of KUIC were doped into UP to obtain a 28.0% limiting oxygen index (LOI) value. Compared with UP, the heat release rate and smoke production of UP/APP/KUIC composites were greatly decreased. Meanwhile, KUIC indeed enhanced the mechanical properties of UP.

Ionic liquid functionalized imogolite nanotubes (INTs-PF₆-ILs) were introduced into the epoxy resin (EP)/ammonium polyphosphate (APP) system to investigate the flame retardant performance and thermal properties using the limiting oxygen index (LOI) test, the UL-94 test, and the cone calorimeter test (CCT). The results suggested that a synergistic effect exists between INTs-PF₆-ILs and APP on the char formation and anti-dripping behavior of EP composites. For the EP/APP, an UL-94 V-1 rating was obtained for the loading of 4 wt% APP. However, the composites containing 3.7 wt% APP and 0.3 wt% INTs-PF₆-ILs could pass the UL-94 V-0 rating without dripping behavior. In addition, compared with the EP/APP composite, the fire performance index (FPI) value and fire spread index (FSI) value of EP/APP/INTs-PF₆-ILs composites were remarkably reduced by 11.4% and 21.1%, respectively. Moreover, the char formed by EP/APP composites was intumescent, but of poor quality. In contrast, the char for EP/APP/INTs-PF₆-ILs was strong and compact. Therefore, it can resist the erosion due to heat and gas formation and protect the inside of the matrix. This was the main reason for the good flame retardant property of EP/APP/INTs-PF₆-ILs composites.

Four types of phosphomolybdates (iron, cobalt, nickel, and zinc) were each combined with antimony trioxide (Sb₂O₃) to prepare polyvinyl chloride (PVC) composites. The effects of the phosphomolybdates on the combustion behavior, smoke release, and mechanical properties of the PVC composites were studied by thermogravimetric analyzer, limiting oxygen index (LOI) tester, smoke density tester, cone calorimeter, scanning electron microscopy (SEM), and universal tensile tester. The results indicate that phosphomolybdates exhibit a significant synergistic flame-retardant effect with Sb₂O₃ in the PVC matrix. Compared with Sb₂O₃ alone, the addition of phosphomolybdates can significantly improve the LOI of PVC composites. It can also reduce smoke release, lower the heat release rate (HRR) of PVC composites, and produce more char residual, which is more continuous and denser. Meanwhile, there is no significant loss of mechanical properties. Overall, nickel phosphomolybdate has been determined to be the most effective of these four phosphomolybdates. Compared with PVC-1, the peak heat release rate (PHRR) of PVC-4 with nickel phosphomolybdate decreased by 13.3%, the total smoke production (TSP) decreased by 37.3%, and the peak smoke production rate (PSPR) decreased by 28.9%. This study demonstrates that replacing some of the Sb₂O₃ with phosphomolybdate can achieve efficient flame retardancy and smoke suppression in PVC. And the results of this study can also provide a reference for future research on the application and promotion of flame-retardant PVC.