Synthesis and characterization of poly(oxazoline) rotaxanes and literature review on separation, detection and identification of cyclic oligomers in poly(ethylene terephthalate) and poly(ε-caprolactam)

Several methods have been developed to determine the cyclic oligomer content in PET. Isolation procedures can be classified as those involving extraction, such as with solvents like chloroform, dioxane, and xylene, and those involving dissolution followed by precipitation in solvents like dimethylformamide and 1-methylnaphthalene. The amount of cyclic oligomer obtained is largely dependent upon the method used, as well as the type, drawing, and thermal history of the PET used.Various methods for separation of cyclic oligomers have also been developed using GPC and thin-layer chromatography.