Dual-exterior surface modification of layered double hydroxides and its application in flame retardant biobased poly(trimethylene terephthalate)

The overall target of this research was to design a dual-exterior surface chemical modification of eco-friendly layered double hydroxides (LDH-S@PA) using calcium stearate and phytic acid (PA) containing-rich phosphorus to synchronously boost the dispersibility in the polymer matrix and the flame retardancy. Microstructure, surface chemical environments and morphologies of LDH-S@PA were characterized. It was found that the target product with the hydrophobic surface was successfully prepared. The basic morphologies of LDH-S@PA exhibited thin flat crystals composed of multi-sheet with hexagonally arranged spots. Meanwhile, the thermal stability of LDH-S@PA was improved. Significantly, after adding LDH-S@PA into biobased poly(trimethylene terephthalate) (PTT) via melting-blending, LDH-S@PA exhibited a higher dispersity in the PTT matrix and the PTT/LDH-S@PA composite with 20 wt% loading achieved 29.8% limiting oxygen index value and possessed V-0 rating in UL-94 test, revealing LDH-S@PA dramatically enhanced the flame retardancy of the PTT. The flame retarded mechanism of LDH-S@PA in PTT was discussed based on gaseous and condensed phase analysis. In addition, the incorporation of LDH-S@PA improved the mechanical properties of the composites. This facile and straightforward approach for dual-surface modification LDHs holds promise as flame retardant formulations for polymer in future applications.

Automated summary

The aim of this research was to design a dual-exterior surface chemical modification of eco-friendly layered double hydroxides (LDH-S@PA) to improve the dispersibility and flame retardancy in the polymer matrix. The study successfully prepared the target product with a hydrophobic surface and improved the thermal stability of LDH-S@PA. The addition of LDH-S@PA into biobased poly(trimethylene terephthalate) (PTT) significantly enhanced the dispersity and flame retardancy of the PTT, while also improving the mechanical properties of the composites. This facile approach holds promise for flame retardant formulations in future polymer applications.