Surface modification of phosphorus-containing hydrotalcite using rare-earth coupling agent and its application in polypropylene

Abstract P3O105− pillared Mg/Al hydrotalcite (HTs P) was successfully prepared by impregnation-reconstruction, and then the HTs-P was modification by rare-earth coupling agent (WOT) to obtain the flame retardant (W-HTs-P) as the filler for polypropylene (PP) matrix. The HTs-P and W-HTs-P samples were characterized using XRD, FT-IR, contact angle measurement, SEM and TG-DTG. The results revealed that W-HTs-P was coated by WOT with smaller particle sizes and their surface property was inverted from hydrophilic to hydrophobic nature. For the W-HTs-P and PP composite (PP/W-HTs-P), the XRD and SEM results indicated that the compatibility between W-HTs-P and PP matrix has been improved. The TGA analysis shown that the char residue rate at 600 °C of PP/W-HTs-P (12.5%) was higher than that of PP/HTs-P (5.3%), and W-HTs-P has proven to enhance the thermal stability of the PP matrix. Besides, W-HTs-P had gained better flammability and mechanical properties for PP matrix. Considering the fact that both the HTs-P and W-HTs-P had a similar layered structure and chemical composition, the improvement of the both physical and mechanical performances of the PP/W-HTs-P composites are due to the slight difference of size distributions resulting from the modification by the WOT.