Eloisa Navarro

The structure of nylon 12,5 is characterized by two hydrogen bond directions as are other polyamides derived from glutaric acid

The structure and morphology of lamellar crystals of nylon 12,5 have been investigated by transmission electron microscopy, electron diffraction and X-ray diffraction. The results obtained indicate that this nylon has a structure different from the conventional α, β and γ forms. Its features are similar to those previously reported for nylon 6,5, which has been shown to have its molecules packed in a network of hydrogen bonds with two spatial orientations (Navarro et al., Macromolecules, 28, 8742). Thus nylon 12,5 should be included in a new family of aliphatic polyamides. The structure derives from a particular conformation of the glutaric units and appears to be independent of the number of methylene groups present in the diamine residue. As a function of the method used in order to prepare the sample, a pseudohexagonal form can also be observed. It might be related to the γ form.

Incorporation of glycine residues in even-even nylons disrupts their characteristic all-trans conformation

Abstract A series of regular polymers derived from the inclusion of glycine in even–even nylons (2,4, 2,6, 4,4 and 4,6) has been prepared by the active ester method. The structure and morphology of lamellar crystals have also been investigated by using transmission electron microscopy, selected-area electron diffraction and X-ray diffraction. The results indicate that at room temperature the structure of these nylons is different from the typical forms (α and β) of even–even polyamides. Observations described in this paper are complementary to previous work about the incorporation of glycine units in nylons derived from ω-amino acids and indicate that glycine residues always tend to adopt their characteristic polyglycine II conformation.