THE STRUCTURE OF NYLON-12,5 IS CHARACTERIZED BY 2 HYDROGEN-BOND DIRECTIONS AS ARE OTHER POLYAMIDES DERIVED FROM GLUTARIC ACID

The structure and morphology of lamellar crystals of nylon 12,5 have b een investigated by transmission electron microscopy, electron diffrac tion and X-ray diffraction. The results obtained indicate that this ny lon has a structure different from the conventional alpha, beta and ga mma forms. Its features are similar to those previously reported for n ylon 6,5, which has been shown to have its molecules packed in a netwo rk of hydrogen bonds with two spatial orientations (Navarro et al., Ma cromolecules, 28, 8742). Thus nylon 12,5 should be included in a new f amily of aliphatic polyamides. The structure derives from a particular conformation of the glutaric units and appears to be independent of t he number of methylene groups present in the diamine residue. As a fun ction of the method used in older to prepare the sample, a pseudohexag onal form can also be observed. It might be related to the gamma form. (C) 1997 Elsevier Science Ltd.