Formation of a flame retardant-cyclodextrin inclusion compound and its application as a flame retardant for poly(ethylene terephthalate)

We report the formation of an inclusion compound (IC) between a commercial flame retardant (FR) and beta-cyclodextrin (CD). The FR-CD-IC was melt-processed into PET films which were tested for flammability. The flammabilities of pure PET films, PET films containing pure CD, and PET films containing FR applied from a bath and then oven-cured, were also observed. Flammabilities, as measured using a modified AATCC Test Method 34, demonstrated that all but the PET films embedded with FR-CD-IC were either completely or substantially consumed when ignited on a single edge with a 3.8 cm flame applied for 3 s. To our knowledge this is the first demonstration of flame retardance achieved by means of delivering a FR to a polymer in the form of its inclusion compound. The high temperature stability of the FR-CD-IC crystals make them suitable for embedding in a variety of polymers that melt below 300 degreesC. Our results suggest that incorporation of FR-CD-IC directly into polymer films or fibers during their melt-processing may be a means to protect them from burning that is superior to post-fabrication application of FRs. In addition, liquid FRs, which are difficult to incorporate and retain in solid polymers, may be included in their high-melting ICs formed with CDs and embedded directly into polymer samples. More broadly, we would expect that a host of other polymer additives may be more effectively delivered in the form of their CD-ICs. (C) 2001 Elsevier Science Ltd. All rights reserved.