Synergistic effects of intercalation of layered double hydroxide with phytic acid-grafted β-cyclodextrin on the flame retardancy of polypropylene

Aiming to enhance the fire resistance and smoke-suppression properties of polypropylene (PP), Phytic acid-grafted cyclodextrins (PCD) is inserted into layered double hydroxide (LDH-PCD) by co-precipitation method and subsequently mixed with PP matrix to fabricate the PP and LDH-PCD composites (PP/LDH-PCD) through melt blending technique. Adequate characterizations verify the targeted structure that the PCD successfully enter the interlayer of the LDH. SEM showed that the dispersion of LDH-PCD in PP had been greatly developed in comparison to LDH. When the addition amount of LDH-PCD to PP is 20%, the limiting oxygen index (LOI) value of PP/LDH-PCD composites is 30.3%. Moreover, cone calorimeter tests (CCT) shows that the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) of PP/LDH-PCD composites exhibit a significant decrease of 90.8%, 73.9%, and 51.9% compared with Neat PP, respectively. These improvements of the flame retardancy is the result of the synergistic roles of the well-designed chemical composition of flame retardant and its uniform dispersion in PP matrix.