Inclusion compounds formed between cyclodextrins and nylon 6

High performance properties are increasingly needed in fibers for industrial applications. Such properties have been achieved in both flexible and intrinsically stiff polymers, but only through specialized and expensive spinning methods. In this work the potential of achieving high performance mechanical behavior in nylon 6 using a conventional spinning process was explored. We report the formation of high-molecular-weight polymer inclusion compounds (ICs) between alpha and beta-cyclodextrins (alpha- and beta-CDs) and nylon 6 (M-n = 12 kg mol(-1)). Both high-molecular-weight polymer ICs were successfully made by a heating technique. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD), and Fourier transform infrared (FTIR) spectroscopy have been utilized to observe the nylon 6 polymer chains included inside the channels formed by the cyclodextrins. DSC and TGA scans showed the high-temperature stable nylon 6-CD-IC samples contain no free crystalline nylon 6 polymer, and the much higher decomposition temperatures observed for these nylon-CD-ICs may imply that polymer chains included inside the polymer CD-IC channels can greatly improve cyclodextrins' stabilities. The nylon 6-alpha-CD-IC and nylon 6-beta-CD-IC X-ray diffraction patterns were very similar to those of valeric acid-alpha-CD-IC and 1-propanol-beta-CD-IC, which were confirmed to be channel crystal structures by single crystal X-ray diffraction. A new band which was absent from the pure cyclodextrin spectrum appeared at 1729 cm(-1) for nylon 6-CD-ICs in their FTIR spectra and may be characteristic for CDs in their channel-forming ICs. (C) 1999 Elsevier Science Ltd. All rights reserved.