Synergistic Flame Retardancy of ABS/PET Blends via Intumescent Flame Retardant and Janus Nanosheets

This study focuses on the development of a synergistic modification system comprising an intumescent flame retardant and Janus nanosheets to prepare acrylonitrile-butadiene-styrene/polyethylene terephthalate (ABS/PET) composites possessing both excellent flame retardancy and mechanical properties. Ammonium polyphosphate (APP) was first modified with N-aminoethyl piperazine (AEP) to successfully synthesize a “three-source-in-one” intumescent flame retardant (m-APP), which was then utilized for the flame-retardant modification of ABS/PET blends. The material achieved a UL-94 V-0 rating and a limiting oxygen index (LOI) of 30.8% when subjected to an m-APP loading of 25 wt %. Furthermore, Janus nanosheets (JNS), featuring styrene-acrylonitrile copolymer (SAN) chains grafted on one side and epoxy groups on the opposing side, were introduced into the system. The JNS not only enhanced the compatibility of the ABS/PET blend but also formed a physical barrier to insulate against material and energy transfer while stabilizing the char layer structure, thereby further improving both flame retardancy and mechanical performance. At a JNS content of 0.75 wt %, the composite achieved a V-0 rating, the LOI increased to 31.7%, and the release of heat, smoke, and toxic gases was significantly reduced while the toughness, strength, and modulus of the material were effectively improved.