The morphology and mechanical properties of nylon 6-polyoxypropylene (POP)-nylon 6 block copolymers as functions of POP content were studied using infrared spectrophotometry, electron microscopy, X-ray diffraction, reheometric measurement and impact testing. The copolymers exhibit a unique morphology having spherulites with feather-like texture, containing POP-rich amorphous domains; the texture varies with POP content. The spherulite is presumed to consist of lamellae, nylon-rich amorphous domains between lamellae and POP-rich amorphous domains outside the interlamellar region. The crystal structure of the copolymers is mainly α-form with a relative shift of hydrogen-bonded sheets in the crystal unit cell. In the dynamic damping spectra, multiple transitions appear in the α-transition range of nylon 6. One is due to the conventional transition of nylon segments, another is due to POP-hydrogen bonded nylon segments. The impact strength is better than that of pure nylon 6 and increases with decrease of POP content. The area of indent zones in the fractured surface change in the same manner as the change of impact strength and POP domain size with POP content. The size and distribution of the POP-rich domains in the spherulites is suggested to be a governing factor for the morphology and properties of the nylon block copolymers.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics