Effect of phosphorus-containing modified UiO-66-NH2 on flame retardant and mechanical properties of unsaturated polyester

A novel phosphorus-containing flame retardant PZN@UiO-66-NH2 was synthesized by covalent bonding between HCCP and UiO-66-NH2, and applied in unsaturated polyester (UPR). The Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron energy spectra (XPS), scanning electron microscopy (SEM) was used to confirm the chemical structure of PZN@UiO-66-NH2. The appearance of new P-N-C bond indicated that HCCP was successfully reacted with UiO-66-NH2. The thermal stability and the flame-retardant properties of the UPR composites were characterized by thermogravimetric analysis (TGA), limiting oxygen index (LOI) and cone calorimeter test. The limiting oxygen index (LOI) of UPR composite with 4 wt% PZN@UiO-66-NH2 can reach 23.9%. Compared with pure UPR, the peak heat release rate (PHRR) value, total heat release (THR) value and average effective heat of combustion (av-EHC) value of UPR composite with 4 wt% PZN@UiO-66-NH2 dropped by 36.53%, 28.70%, 23.50%, respectively. The addition of PZN@UiO-66-NH2 slightly improved the impact performance of UPR composite. PZN@UiO-66-NH2 can solve UiO-66-NH2's agglomeration dilemma in UPR to some extent.