Abstract
The influence of the main variables (temperature and strain rate) of the drawing process on the structure and dynamic mechanical relaxations of vinyl alcohol-ethylene (VAE) copolymers with higher content in the former counit is studied. The structure of VAE copolymers is considerably modified by drawing, which produces a disordered crystalline form, as revealed by WAXD and DSC measurements. The structural changes have significant effects on the viscoelastic relaxations of stretched VAE copolymers. A remarkable increase in the storage moduli is observed in the direction parallel to the uniaxial orientation, depending on composition and drawing parameters. The drawn copolymers show an additional α relaxation taking place at temperatures higher than that of the α relaxation (glass transition), attributed to motions within the crystalline regions. The β mechanism is moved to higher temperatures for the stretched specimens and its intensity is considerably increased. Finally, the γ relaxation is very weak and only displayed in the sample with the higher ethylene content.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
