Eco-friendly and rapid microwave synthesis of P-doped carbon dots and its application in the improvement of fire safety for polyethylene terephthalate

As the most widely utilized thermoplastic polyester with the largest production volume, PET is primarily used in clothing, curtains, plastic films, and electronic appliances, all of which have high safety performance requirements, particularly in terms of fire resistance. In this study, a bio-based integrated phosphorus-containing flame retardant (PCDs) was efficiently prepared using phosphoric acid and biomass material gelatin as raw materials, employing a rapid microwave-assisted method. Subsequently, PCDs was copolymerized into the PET matrix (PET-PCDs) through in situ polymerization, achieving enhanced flame retardancy. The combustion properties and flame retardancy mechanisms were analyzed using CONE, TG-IR, and py-GCMS. The results showed that the peak heat release rate of PET-PCDs decreased by 54.02% when the PCDs content was only 1.0 mass%. Additionally, the yield of CO and CO 2 decreased by 9.00% and 16.67%, respectively. In terms of fire risk, compared to PET, the fire growth index of PET-PCDs decreased by 64.07%, and the fire performance index increased by 51.61%. Furthermore, the tensile strength of PET-PCDs was not significantly affected, and the elongation was improved. This study offers a promising solution for the development of eco-friendly and integrated flame retardants for PET.