Novel fire resistant matrixes for composites from cyclic poly(butylene terephthalate) oligomers

The objective of the work is to exploit the processing advantages of c‐PBT oligomers, essentially required in industrial practice to produce new, robust, multifunctional hybrid copolymers of c‐PBT oligomers in a single reaction‐molding step, which will be suitable for the use in continuous fiber composites with excellent flame retardant properties. In this article a series of copolyesters were synthesized by using in situ polymerization of cyclic poly(butylene terepthalate) oligomers (c‐PBT) and hydroxyl terminated bisphenols and hydroxylated siloxanes in the presence of a tin catalyst at a moderate temperature. The in situ copolymerization was conducted with various c‐PBT/tetrabromobisphenol A (TBBPA), bisphenol A diglycidyl ether (BPADGE) and Carbinol PDMS feed ratios respectively. The copolyesters were characterized by GPC, NMR, and DSC techniques. Pyrolysis‐combustion flow calorimeter (PCFC) and pyrolysis gas chromatography/mass spectrometry (PyGC/MS) studies were performed to characterize the fire retardant properties of the copolymers during combustion. POLYM. ENG. SCI., 47:1536–1543, 2007.