2.1 Determination of Tensile Strength and
Elongation
Tensile strength and percent elongation
were tested by using the Instron Universal Testing
Instrument model 5565 (Instron, Canton, MA, USA)
following ASTM D638M (ASTM, 1993). Film
specimens were cut into rectangular strips (1 cm x
10 cm). The initial grip separation was 5 cm and the
cross-head speed was 25 mm/min. Tensile strength
was calculated by dividing the maximum load by the
cross-sectional area (average thickness × 1 cm) of
the initial specimen. The percentage elongation was
defined as the percent change in the length (ΔL) of
the specimen to its original length (L) between the
grips (5 cm). Tensile strength and percent elongation
results were obtained from 10 sample replications.