Abstract: A polysiloxane modified β-cyclodextrin (CDS) was synthesized from tetramethyl dihydro disiloxane, allyl glycidyl ether, and β-cyclodextrin (β-CD). FTIR showed that β-CD was grafted to the chain ends of polysiloxane. The prepared CDS was employed in a flame retarding polypropylene system containing also an intumescent flame retardant (IFR), and compared with unmodified β-CD in the thermal and mechanical properties using thermogravimetric analysis (TGA), limiting oxygen index (LOI), scanning electron microscopy (SEM), etc. It showed that CDS had a synergistic effect with IFR, which promoted the formation of stable, continuous and compact char structure at high temperature. When the content of CDS was 1.5 wt%, the LOI was 35.0 %, pass the UL94 V-0 test. The tensile, flexural, and impact strength were 8. 6 %、16.8 % and 70.7 % higher, respectively, than those based on β-CD.

Key words: silicone, β-cyclodextrin, instumescent flame retardant, synergistic effect