Abstract
Infrared spectra and x-ray diffractions of 24 nylons were investigated. The positions of the NH stretching and the amide I bands indicate that the amide groups form hydrogen bonds almost completely, irrespective of the number of CH2 groups. The position of the amide V band has been correlated with the crystal structure. Nylons characterized by a predominant peak at 725 cm.−1 show only one reflection in the x-ray photograph. Odd-odd nylons belong to this type (γ form). Even-odd and odd-even nylons also take this γ form when prepared from the melt through quenching. When cast from solution, they seem to take a new form. Amino acid nylons with an odd number of CH2 groups have a tendency to take the γ form. Three bands closely related with the position of the amide V band are found.