Before revision: These are some plastics that may degrade, but are not seriously harmful to nearby objects: Cellulose esters Non-plasticized (rigid) polyvinyl chloride (PVC) The following are "malignant" plastic materials that will age rapidly if left untreated, and which have a higher risk of off-gassing or releasing toxic materials that can damage surrounding objects: Polyvinyl chloride treated with plasticizers Polyurethane Cellulose nitrate Cellulose acetate Vulcanized rubber Biodegradable plastics Environmental concerns have driven recent changes in plastic manufacturing towards biodegradable plastics, with a potentially negative effect upon the long-term stability of such materials within museum collections.
After revision: These are some plastics that may degrade, but are not seriously harmful to nearby objects: Cellulose esters Non-plasticized (rigid) polyvinyl chloride (PVC) The following are "malignant" plastic materials that will age rapidly if left untreated, and which have a higher risk of off-gassing or releasing toxic materials that can damage surrounding objects: Polyvinyl chloride treated with plasticizers Polyurethane Cellulose esters, including cellulose nitrate and cellulose acetate Vulcanized rubber Biodegradable plastics Environmental concerns have driven recent changes in plastic manufacturing towards biodegradable plastics, with a potentially negative effect upon the long-term stability of such materials within museum collections.