Preparation and characterization of cyclodextrin microencapsulated ammonium polyphosphate and its application in flame retardant polypropylene

A novel microencapsulated ammonium polyphosphate (MAPP) with shell of crosslinked beta-cyclodextrin (HDI-CD) was prepared. The HDI-CD shell had a fibrous structure and covered with good completeness on the APP core, and a solid chemical bonding was found between the APP core and HDI-CD shell. The microcapsules were more hydrophobic than the pristine APP. When compounded within polypropylene (PP), the MAPP exhibited good compatibility and dispersibility. The combustion testing results showed that the novel all-in-one intumescent flame retardant had efficient flame retardancy for PP materials.