INFLUENCE OF MICROSTRUCTURE DEVELOPED DURING DRAWING ON SURFACE-PROPERTIES OF POLY(ETHYLENE-TEREPHTHALATE) FILM

We have measured the surface wettability of poly(ethylene terephthalat e) (PET) film drawn to different draw ratios at strain rates of 0.56 a nd 0.01 s-1 and a draw temperature of 90-degrees-C. The probe liquid w as demineralized water. We believe that the observed changes in advanc ing and receding work of adhesion-and in the wetting hysteresis indica ted by their difference-reflect a lowering of the energy state of the film surface during drawing, due to increases in 'amorphous orientatio n' and the onset of crystallization. Orientation-induced interaction b etween PET molecules may reduce the availability of sites that would o therwise interact with water.