Synergistic modification of long-chain polyamides with brominated polystyrene/Sb 2 O 3 for high-performance flame-retardant PA66 composites

Abstract In this study, ternary blends of polyamide 66/polyamide 610/polyamide 12 (PA66/PA610/PA12) were firstly prepared, and exhibited the best mechanical performance when the mass ratio of PA610 to PA12 was 2:3 and their total content was 20 wt%. On this basis, the ternary blend was mixed with glass fiber (GF), brominated polystyrene/antimony trioxide (BS) to prepare a PA66 composite (PA66/610/12/BS/GF), and the samples without long chain polyamides and flame retardants (PA66/BS/GF and PA66/610/12/GF) were also prepared for comparison. DSC and XRD analyses showed that PA610 was immiscible with PA66 after short-time blending. Besides, long-chain polyamides (PA610 and PA12) and flame retardants, especially Sb 2 O 3 , increased the crystallinity ( X c ) of PA66 in the composites, leading to the highest X c of PA66 in PA66/610/12/BS/GF. SEM images revealed that BPS was dispersed in the polyamide matrix at a microscale size. Mechanical tests revealed that long-chain polyamides and flame retardants exhibited a synergistic effect, which could simultaneously enhance the strength and toughness of PA66/GF, and promote its charring reaction and char residue yield. In addition, all the composites containing flame retardants showed excellent flame retardancy, reaching the UL-94 V-0 rating. Therefore, PA66/610/12/BS/GF is a composite with UL-94 V-0 flame retardancy, high strength, high toughness and good thermal stability, and can be used for components requiring high comprehensive performance in the electrical and electronic, automotive and home appliance fields.