Preparation and property analysis of kaolin/melamine cyanurate/aluminum diethylphosphinate/recycled PET composites

Abstract In the plastic industry, recycling waste plastic was an effective way to save energy and reduce emissions, therefore, using recycled PET (R‐PET) to produce flame retardant PET could not only improved the recycling value of discarded PET, but also conducive to achieving carbon neutrality. The effects of melamine cyanurate (MCA), aluminum diethylphosphinate (ADP) and kaolin (Kaol) on flame retardant, combustion behavior, thermal degradation behaviors and mechanical properties of R‐PET composites were investigated by methods of limited oxygen index (LOI) measurement, vertical burning test, cone calorimeter test, thermogravimetry analysis (TG), SEM analysis and mechanical properties test. The results showed that MCA, ADP and Kaol could improve the flame retardant of R‐PET, and ADP had the best effect on improved the flame retardant of R‐PET. MCA and ADP had synergistic flame retardant in R‐PET, but MCA had a negative effect on the mechanical properties and thermal decomposition temperature of ADP/R‐PET composite. Kaol could not only improve the flame retardant and thermal decomposition temperature of MCA/ADP/R‐PET composites, but also improved their tensile and flexural strength. The flame retardant of 4‐Kaol/5‐MCA/15‐ADP/R‐PET composite reached UL94 1.0 mm V0 with LOI was 36.5%, and the tensile and flexural strength were increased by 26.1% and 16.7% compared with 5‐MCA/15‐ADP/R‐PET, respectively.