The effect of sunlight on medium density polyethylene Water pipes

The suitability of medium density polyethylene (MDPE) water pipes beyond (2 years) being stored outdoors was studied. The resistance of MDPE pipes to ultraviolet (UV) radiation was evaluated by measuring changes in tensile strength at break. MDPE pipes under study have two formulations: the first without carbon black (virgin) and the anther with carbon black, the samples were exposed to UV radiation using an accelerated weatherometer for (200 h) to simulate the effect of (2 years) of exposure to sunlight. The values of tensile strength at break of MDPE with C.B have higher values (160.7Kg/cm2) than virgin MDPE(137Kg/cm2) after exposure MDPE with C.B cutoff at 25% of strain with tensile strength about (161Kg/cm2) before exposure to UV radiation, but it is cut off at 50% of strain with the same value of tensile strength after exposure. The percentage of carbon black and the degree of its dispersion have been determined by employing thermogravimetry (TGA) technique and reflected light microscopy respectively