The procedure used to prepare the films for
testing of mechanical properties was adapted from
ASTM standard test method for tensile properties of
thin plastic sheeting (ASTM, 2001). Film samples
were cut into 120 mm x 10 mm dumb bell strips
and thickness of the individual specimens was
determined as a means of five measurements taken
over the gage length. It was then used to estimate
the cross-sectional area. The tensile properties were
determined using a TA-HDi Texture Analyzer (Stable
Micro Systems Ltd. Surrey, England) with a load cell
of 25 kg and crosshead speed of 1.0 mm/sec. Film
samples were clamped between grips, leaving an
initial distance between the grips of 75 mm. Tensile
Strength (MPa) was calculated by dividing the
maximum load (N) necessary to pull the sample film
apart by the cross-sectional area (m2). Percentage of
elongation at break was calculated by dividing film
elongation at the moment of rupture by the initial grip
length of samples multiplied by 100%. A total of 10
samples were tested for each film type.