Facile fabrication of cyclodextrin-based and integrated flame retardant in intumescent flame-retarding polypropylene

A hydrophobic, beta-cyclodextrin-based and halogen-free flame retardant (MCDPM) with three components in an integrated structure has been prepared by a facile method. Three traditional intumescence flame-retardant components were chemically combined into one compound. The aim of this paper was to improve the dispersion and flame retardancy in polypropylene (PP) via introducing a mono-component biomass-based compound. The structure and properties of MCDPM have been systematically investigated. To prepare samples for flammability testing, MCDPM particles were introduced into polypropylene (PP) via melt blending. The thermal stability of the blend was dramatically greater than that of PP. Notably, the limiting oxygen index (LOI) for PP/30 phr MCDPM blend was 26.4% and the blends could pass UL-94 V-1 ratings, demonstrating that the flame retardancy of PP could be enhanced by introducing MCDPM. Through the systematic analysis of the char residue, a possible intumescent flame-retardant mode of action has been proposed.