Abstract
Lamellar crystals of nylon 6,8 and nylon 8,10 with chains in a fully extended conformation were obtained by crystallization in solution, and examined by electron and X‐ray diffraction. The same crystal structure appeared to be shared by both nylons crystallized in glycerin. This structure consisted of a mixture of α‐ and β‐forms with features similar to that previously described for lamellar crystals of nylon 4,6 grown in the same solvent. Crystallization of nylon 8,10 in hexane‐2,5‐diol afforded lamellar crystals with sheets stacked in the β‐form. A comparative energy evaluation of the different models that are feasible for the crystal structure of these nylons with fully extended chains indicated very small energy differences among them. The presence of different chain arrangements in the same lamellar crystal, as well as the crystallization of the same nylon in different crystal forms upon slight modification of the crystallization conditions, are fully consistent, therefore, with the results obtained in the energy analysis.
Nylon 8,10 crystals grown in hexane‐2,5‐diol at 150 °C. Inset: The respective electron diffraction patterns.
magnified imageNylon 8,10 crystals grown in hexane‐2,5‐diol at 150 °C. Inset: The respective electron diffraction patterns.