Effect of UV Radiation on the Mechanical and Rheological properties of LLDPE and HDPE films

The effect of varying the intensity, time and illumination pattern of ultraviolet radiation on the mechanical properties of linear low density polyethylene (LLDPE) and high density polyethylnene (HDPE) has been studied. Varying the illumination pattern was achieved using a perforated metal sheet. It has been found that the tensile strength, modulus of elasticity and elongation at break decrease when LLDPE is subjected to high intensity radiation in the presence of a screen. Conversely, low intensity radiation in the presence of a screen causes these mechanical properties to increase. Rheological measurements indicate that these changes are correlated with changes in the molecular architecture of the films. The interaction between the screen and high intensity radiation causes the material to degrade