Ultrafine hydrotalcite particles prepared with novel technology to improve the flame retardancy of polypropylene

Ultrafine Mg/Al hydrotalcite particles (RMAH) were synthesized by co-precipitation in high-gravity environment generated by a rotating packed bed reactor with (NH 4 ) 2 CO 3 as precipitant. Sodium tripolyphosphate modified RMAH (S-RMAH) was investigated as potential flame retardant for polypropylene (PP) material. The RMAH and S-RMAH materials were characterized using XRD, SEM/EDS, TG–DTG, FT-IR, BET, particle size distribution, pH point of zero charge and so on. The S-RMAH particles which were coated by P 3 O 10 5 − possessed smaller particle sizes and narrower sizes range, and their surface property was modified from hydrophilic to hydrophobic nature. As novel functional fire-retarding nanofillers, the RMAH and S-RMAH were used to prepare PP/RMAH and PP/S-RMAH composites, aiming to investigate the effect of the nanofillers on the flammability, compatibility and mechanical properties of PP material. The thermal stability, morphological and flame retardant properties of the two composites were determined by SEM, TGA, LOI and UL94 analyses, and their mechanical properties were also characterized. The results showed that the RMAH and S-RMAH could significantly enhance the thermal stability, flammability and mechanical properties of PP material, and the S-RMAH had better performances as a flame retardant for PP than the RMAH. It offered a new approach to preparing ultrafine hydrotalcite nanoparticles with high anti-flaming performances.