Thermal and Mechanical characterisation of films from Nylon 6/EVOH blends

Blown films from blends of dispersed ethylene-co-vinyl alcohol copolymer in a Nylon 6 matrix were characterised thermally and mechanically in humid laboratory conditions. Preliminary evaluations in terms of tensile tests revealed a non-equilibrium state for all the prepared Nylon 6/EVOH ratio based systems. Dynamic mechanical tests on films from blends appeared to indicate the occurrence of a single glass transition temperature (Tg) located between the Tg of the two homopolymers. However the Tg composition trend did not follow a monotonic path showing a maximum for EVOH contents close to 25% by weight. At this composition, the highest environmental ageing and the minimum of static tensile properties of blown films were also evident. Thermogravimetric analysis of all the investigated samples revealed an equilibrium water up-take close to 2% by weight with a maximum of 2.6% by weight for pure polyamide films.