Premium
The crystal structure of nylon 3,5 and nylon 5,7: a comparative study
Author(s) -
Bermúdez Marta,
León Salvador,
Alemán Carlos,
Bou Jordi J.,
MuñozGuerra Sebastián
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19990901)200:9<2065::aid-macp2065>3.0.co;2-8
Subject(s) - nylon 6 , lamellar structure , crystal structure , nylon 66 , materials science , polymer , crystallography , hydrogen bond , polymer chemistry , chemistry , polymer science , composite material , molecule , organic chemistry , polyamide
A comparative analysis of the crystal structure of nylon 3,5 and nylon 5,7 was carried out. Lamellar crystals of both compounds were grown from diluted solutions and examined by electron microscopy and X‐ray diffraction. A structure with chains in fully extended conformation was the only modification found for nylon 3,5. A similar structure was found also for nylon 5,7 although the structure largely preferred by this nylon is the contracted γ‐form. A rational explanation for the dissimilar behavior displayed by the two nylons was provided by a comparative estimation of their packing energies using molecular mechanics methods. Details concerning the displacement of sheets in nylon 3,5 and the arrangement of hydrogen bonds in the γ‐form of nylon 5,7 were further unraveled by energy calculations. All these features were discussed with regard to the chemical constitution of the polymers and to the structures reported for other closely related nylons.