The tensile strength, elastic modulus and elongation of films were measured according to the ASTM standard D882-97 using an Instron Universal Testing Machine model 5569 with a 50 N load cell. Film specimens were cut as a rectangular center, 10 mm wide and 100 mm long, flaring to 25 mm*30 mm grip areas on both ends and then preconditioned at 25 ± 2 C and 50 ± 5% RH for at least 48 h. The initial gauge separation and the crosshead speed were set to 100 mm and 50 mm/min, respectively.