Analysis of degradation products founds in surveys
Under exposure to light and ultra violet radiation, and under the influence of temperature, oxygen and high humidity, chemical reactions take place in plastics and lead to modification of their properties.
This might lead to the formation of degradation products that are released by the artefact. When surveying a collection, the most obvious phenomenon is the presence of deposits either liquid or solid on the surface of degraded objects. It corresponds to the migration of compounds added during plastic manufacturing. One also might smell some characteristic odours emitted by plastics by off-gassing of volatile organic compounds (VOCs). Whenever it was possible, corrosion products, VOCs and deposits were sampled on plastic artefacts and analysed in the lab. Among all the works surveyed, seventeen were singled out for presenting degradation products to be analysed. The majority was in solid form, crystal or powder, and only three in liquid form. Relevant VOCs were identified in some cases.