A Raman study of nylon 6 annealed under high pressure

Using a cubic-anvil high pressure apparatus, nylon 6 samples were annealed under 400 MPa to 1.5 GPa. The structure changes of nylon 6 are studied by the methods of wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and Raman spectra. Compared with sample prepared at ambient pressure, high pressure treatment makes the hydrogen-bonded sheets pack more closely and thus enhanced CH2 vibration out of the hydrogen-bonded sheets. After high pressure treatment, it is observed that all changes of C-C related vibration modes in nylon 6 are similar with ones in nylon series when the CH2 sequence number increased, from which it is deduced that high pressure treatment reduces the effects of amide group on the chain conformation of nylon 6.