Mechanical properties. Twelve samples, 2.54 cm wide and 10 cm long, were cut from the ISP-coated paper. Samples
were conditioned for 48 h at 25°C and 50% relative humidity (RH) in an environmental chamber before measuring tensile
strength (TS) and elongation (E). An Instron (model 4210; Instron Engineering Corp., Canton, MA) was used to measure
TS and E at breakage, according to ASTM standard method D 882-88 (22). Initial grip separation and crosshead speed
were set at 50 mm and 500 mm/min, respectively. Peak loads and extension at the breakage point were recorded for the
tested film samples. TS was calculated by dividing peak loads by specimen cross-sectional areas. The thickness of individual samples, required to calculate cross-sectional area, was determined by averaging five micrometer readings taken on each sample before testing. Extension values were divided by the initial grip separation (50 mm) and multiplied by 100 to yield percentage E at breakage. Units used are Pascal (Pa) and percent (%) for TS and E, respectively.