UV Effects on the Tensile and Creep Behaviour of HDPE

The tensile and creep behaviour of a high-density polyethylene grade used to manufacture pipes were evaluated as a function of the time of exposure to UV radiation. The effect of the creep stress level was also analysed. A threshold radiation dose was determined, above which UV radiation causes loss of the macroscopic mechanical behaviour for this particular HDPE grade. Below the threshold value, macromolecular modifications were also taking place, but the deleterious effect of UV radiation was masked by the development of a more rigid structure. Scanning electron microscopy, melt flow index and thermogravimetric analysis were used to support the results of the mechanical analysis.