FORMATION OF THE SURFACE-STRUCTURE OF POLYETHYLENE-TEREPHTALATE (PET)DUE TO ARF EXCIMER-LASER ABLATION

The development process of the surface structure on polyethylene-terep htalate (PET) has been investigated. It was found that the average dim ension and shape of its unit cells depend on the excimer laser fluence , the incident angle of the ablating laser beam (the longitudinal dime nsion is proportional to cons X tan(alpha)+D formula, where D means th e average dimension of the unit cell at alpha = 0 degrees) and the num ber of shots (the average dimension and height proportional to the log arithm of the number of shots). A dye laser based arrangement was cons tructed to investigate the temporal dependence of the scattered probe light intensity from the ablated polymer surface. It was found that th e formation of the surface structure takes place in the time range of 5-10 mu s. We used a heat diffusion melting model to explain the devel opment of the surface structure. A simple 1D simulation of the heat tr ansfer shows that the lifetime of the liquid phase (similar to 1-7 mu s) is comparable with the time scale mentioned above.