Effect of nitric acid on the properties of polyolefins

This research work studied the effect of aggressive media on polyolefins, specifically, HDPE, MDPE, LDPE, LLDPE and PP. Their selection was made because polyolefins are noted for their high resistance to water, solvents and most chemical reactants. Further, polyolefins are the biggest selling plastics material, which makes their study note worthy.;The polyolefins under study were molded and then immersed in the selected aggressive media (nitric acid) for a maximum of sixty days during which samples were removed after one, two, three, four, five, seven, fourteen, twenty-one, thirty and sixty days. A series of tests was conducted on the untreated and treated samples to study the degradation mechanism and quantify the extent of degradation.;A significant loss was observed in the tensile strength of the polyolefins. However, the extent of loss depended on the morphology, structure, density and MI, to name a few, of the specific polyolefin. Further, the impact behavior and the DTUL test suggested that the onset of degradation depended strongly on the density. Nevertheless, the structure and molecular chain length determined the rate and extent of degradation to a large extent.