Crystalline order in nylon 66

The x‐ray diffraction patterns of nylon 66 at small and large angles have been correlated with the densities of samples prepared in various ways. Quenching from the melt to 0°C. produces structures which are less than 40% crystalline, as determined by density and have structures similar to nematic liquid crystals. More dense specimens have a triclinic structure and appear to contain lamellae 50–100 A. thick which consist of outer amorphous layers and a central portion which is about 80% crystalline. Thermodynamic and spectroscopic evidence indicates that the disorder on melting consists of rotations about the bonds connecting CH2groups.