Sunday, October 26, 2008

Long Live Plastics

Science News: "Because plastic products can be mass-produced cheaply, they have long been considered the poster child of a throwaway culture. Plastics are versatile: Some are soft and flexible, but others are completely rigid. A few mimic natural substances; some are infused with colors rarely found in nature. Others are as clear as glass. And some polymer substances composing plastics can be molded into shapes impossible to reproduce with materials such as wood.
Perhaps because they are so versatile, some objects made from plastics have become highly collectible. Some museum collections, in fact, specialize in items commonly made of plastic — toys, games and dolls, for example. Other museums couldn’t avoid the polymers if they tried: Plastics show up in everything from fabrics to furniture, sequins to sculpture.
Though often praised for their chemical stability, plastics don’t last forever. Vinyl can crack, polyurethane can get cloudy and flexible tubing can become stiff. Even Ken and Barbie, like anyone approaching 50, can succumb to blemishes, age spots and loss of skin tone.
A decade ago, a survey of museum collections in London confirmed the ephemeral nature of polymers: About one out of every eight plastic items showed signs of physical degradation such as cracking, discoloration or deformation, says Bertrand Lav├ędrine, an analytical chemist at the National Museum of Natural History in Paris. That doesn’t mean the other plastic objects will stay in good shape. Even items that appear fine for long periods can suddenly deteriorate once chemical changes start, he notes.
Most chemical changes triggering polymer degradation are irreversible. But given the right conditions, the demise of plastics can be slowed. Often, however, the challenge is to find those conditions.
“The museum world, in particular, has suffered badly from a lack of detailed understanding about the materials and techniques used for the manufacturing, the conservation and the restoration of artifacts that are now in critical condition,” says Lav├ędrine.
Hence the need for the POPART project. This 42-month, multimillion-dollar program — whose name is a shortened version of “Preservation of Plastic ARTefacts in museum collections” — was launched in October to address many of the problems that curators now face. Funded by the European Commission, researchers from the dozen participating museums, government agencies and universities in eight countries will survey museum collections, study how certain polymers deteriorate, develop techniques to display and clean plastic items and design equipment that can quickly discriminate one type of plastic from another."

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