Tensile properties of all films were determined with a 3340 Series Single Column System Instron Instrument, LR30K model (Fareham Hants, UK) equipped with a 2 kN load cell. The main tensile
parameters, such as elastic modulus and elongation at break, were calculated from stress–strain curves according to ASTM D882-09 Standard procedure (ASTM D 882-09, 2009). Before testing,
all samples were conditioned for 48 h at 25 C and 50% RH. Tests were performed with 100 10 mm2 rectangular probes and initial grip separation of 60 mm. The specimens were stretched at 10 mm min1 until breaking. Results were the average of five measurements (± standard deviation).