Intumescent Flame-retardant Modification of Polypropylene/Carbon Fiber Composites

To improve the flame resistance of polypropylene (PP)/carbon fiber (CF) composite materials, triazine char-forming agent (TCA) was compounded with ammonium polyphosphate (APP) or modified APP (CS-APP) in a 2:1 ratio to prepare intumescent flame retardant (IFR) and the modified intumescent flame retardant (CS-IFR) in this paper. Flame retardancy and thermal degradation behaviors of the composites modified by IFR and CS-IFR were characterized by Fourier Transform Infrared (FTIR), contact angle measurement, oxygen index (OI), vertical burning tests (UL-94), thermogravimetric analyer (TGA), and thermogravimetric analyzer coupled with Fourier transform infrared (TG-FTIR). It was found that 25.0 phr of IFR and 24.0 phr of CS-IFR could improve the LOI value of PP/CF composites to 28.3% and 28.9%, respectively. At the same time, a UL-94 V-0 rating was achieved. The experimental results show that the IFR and CS-IFR prepared could effectively improve the flame retardancy and thermostability of PP/CF composites, and they would greatly expand the application range of PP/CF composite materials.