The surface pH of the prepared films was measured by bringing electrode in contact with film surface and allowed to equilibrate using a pH meter (Jenway 3310, UK). The test was done in triplicate and the results expressed as mean ± SD. (Satyanarayana and Keshavarao , 2012)
Mechanical characteristics
The tensile properties test was performed by using a Chacillon force measurement apparatus (Greenspora, NC27409, Mumbai, India) in which the tensile strength, percent elongation and elastic modulus were measured. The apparatus has two clamps the upper is fixed and the lower is movable. The film sample (1x3 cm) was clamped between the two clamps. The test was done in triplicate for each film formula (EL-Setouhy and Abd El-Malak, 2010). The tensile strength, percent elongation (%E) and elastic modulus were determined using the following equations:
Tensile strength = Load at failure × 100/Strip thickness × Strip width (1)
% E = [(Ls- L0)/L0] x l00 (2)
Where L0 is the original length and Ls is the length of the film after