Thirty year ageing of plastics

The report provides details of a 30-year programme to investigate the ageing of six plastics under various climatic conditions. The plastics comprised three types of polyvinyl chloride (PVC); a styrene-butadiene copolymer; and both low and high density polyethylenes. Specimens of each plastic were stored at sites with temperate, hot and wet, and hot and dry environments. At intervals throughout the programme, tests were performed to determine any changes in the physical properties of the plastics. There was little change in the properties of the polyethylenes and a PVC plasticised with dioctyl phthalate. However, the properties of the other plastics changed over the 30-year period due to a reduction in the effectiveness of the plasticisers or stabilisers.