A new article from Ning Yan’s lab has been published in the Chemical Engineering Journal written by Cheng Hao, Daniel Davidson, Haonan Zhang, Alper Alper, Shawn Prevoir and Ning Yan.

You can find the article here.

Abstract

The flammability of polycarbonate/acrylonitrile butadiene styrene (PC/ABS) significantly restricts its use in safety-critical applications, despite its desirable mechanical and thermal properties. Bio-based, halogen- and PFAS-free flame retardants have gained interest as sustainable alternatives to conventional halogen-based flame retardants for engineering thermoplastics, yet most exhibit insufficient thermal stability for the demanding processing temperatures (>250 °C) required by high melting point engineering thermoplastics, such as PC/ABS. To overcome this fundamental thermal stability bottleneck, in this study, a reactive compatibilization strategy was developed to tailor a thermally robust and compatibilized lignin-derived flame-retardant system for PC/ABS. Nitrogen and phosphorous modified lignin was pre-compounded with styrene-maleic anhydride copolymer (SMA), which not only significantly raised the onset decomposition temperature (T_d5 = 293 °C) to withstand the high-temperature compounding, but also ensured uniform dispersion within PC/ABS. This strategy enabled, to the best of our knowledge, for the first time, effective incorporation of a bio-based flame retardant into engineering-grade PC/ABS at industrial relevant loadings. With the addition of 5 wt% LNP and 10 wt% SMA, the PC/ABS blends achieved the UL-94 V-0 rating with an increased limited oxygen index (LOI) and a 51.5 % reduction in peak heat release rate, while significantly enhancing heat deflection temperature and maintaining tensile strength of the PC/ABS samples. Mechanistic investigations revealed a synergistic condensed-phase barrier effect from crosslinked phosphorus-rich char and a gas-phase radical-quenching effect to suppress flame propagation. This work aligns with current regulatory drivers to replace halogenated and PFAS-based additives, showing a viable pathway for developing sustainable and high-performance flame retardants for engineering thermoplastics with high melting temperatures.