Structural Characterizations Of Nylon 6 And Nylon 6/Montmorillonite Nanocomposites

We observed a very unusual crystallization behavior in Nylon 6 by X-ray diffraction. The melted Nylon 6 films were quenched in oil baths with different temperatures for isothermal crystallization. When the Nylon 6 films were isothermally crystallized above 180°C for 30 min and then quenched in ice water,three sharp diffraction peaks at 2θ=9.4°,18.95°and 28.5°were observed in X-ray diffraction patterns. No diffraction peaks could be found at 2θ=9.4°,18.95°and 28.5°from a series of calculated 2θvalues for theα,β,γand pleatedαform crystals of Nylon 6. The locations of these peaks do not correspond with calculated 2θvalues. When the film was slowly cooled from the melt state to 180°C and was maintained at 180°C for 30 min and then quenched to 0°C,it could be found that these three reflections disappeared. If the Nylon 6 film isothermally crystallized at 180°C for 30 min was not quenched to room temperature,but cooled to room temperature in air,these three diffraction peaks could not be observed.Variable-temperature X-ray diffraction was used to monitor the crystalline transition of Nylon 6 and Nylon 6/montmorillonite nanocomposite. It could be found that theα-phase of the pure Nylon 6 sample transforms into aγ-phase at above 190℃,if the sample was heated from room temperature to a high temperature,which is the so-called Brill transition of Nylon 6.At the same time,there was a tendency of Brill transition in Nylon 6/montmorillonite nanocomposite. From melting condition to cooling to room temperature , Nylon 6 and Nylon 6/montmorillonite nanocomposite preserved theα-phase,revealing two peaks in their WXRD patterns,the reverse transition fromγ-form toα-form of the pure Nylon 6 sample could be observed ,indicating reversible Brill transition tendency of Nylon 6/montmorillonite nanocomposite.The crystal transitions of Nylon 6 drawn at different temperatures with differentdrawing ratios were investigated by wide-angle X-ray diffraction. Theα-form Nylon 6 was only partly transformed into theγ-form when it was drawn. The thermal inducement was favorable to producing theα-form,while the drawing inducement was favorable to producing theγ-form.