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Modern Synthetic Materials
Study of modern synthetic materials is a fairly recent activity at the Laboratory, Department of Conservation.
There is almost no area of human activity today which does not involve the use of plastics, examples include photographic film, medical equipment, furniture, clothes, toys, transport, packaging materials, paint and adhesives. Since they are so familiar to us, it is difficult to understand that entirely manmade plastics were only first developed around 1910 and many were only available after World War 2. |
Bevaringsafdelingen
IC Modewegsvej, Brede
DK-2800 Kgs. Lyngby
Tlf: +45 33 47 35 02
Fax: +45 33 47 33 27
E-mail: |
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Right: PVC Poster advertising ‘The Plastics Age; from Modernity to Post-Modernity’ exhibition held in 1990 at the V&A Museum, London.
Plastics are materials composed of giant molecules known as polymers which can be converted into solid shapes from liquid form by applying heat and pressure. Today there are fifty different basic types of polymers, but their chemical and physical properties may be changed by adding other materials. Fillers are added to introduce opacity, stabilizers to combat the deteriorating effects of light and heat and colouring agents for cosmetic effect. The finished products are known as plastics.
Degradation of plastics
Although many manufacturers and designers thought that plastics would last forever, their deterioration is clearly evident in museum and private collections, sometimes only 5 years after acquisition. Once a plastics material begins to deteriorate, the process cannot be reversed or stopped, only slowed.
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Research into extending the useful lifetime of plastics |
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Right top: Attenuated Total Reflection accessory for Fourier Transform Infrared (FTIR) spectroscopy is used to identify chemical groups at surfaces of plastics materials non-destructively
Right bottom: FTIR transmittance spectra are definitive to plastics type
Research into the degradation and prolonging the useful lifetime of plastics in the Laboratory at the National Museum includes:
Analysis of polymer types, additives and degradation products present.
It is important to identify the chemical structures before the cause of degradation can be understood. It is difficult to identify the type of plastic only from its appearance because many early plastics were developed to imitate expensive natural materials.
Fourier Transform Infrared (FTIR) spectroscopy is the definitive technique used in the Conservation Research Laboratory. It identifies the chemical groups present, and can be used without damaging plastics materials. |
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Identifying the causes of deterioration |
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Right top: Acetic acid produced by the degrading cellulose acetate handles of these knives has burned the wrapping tissue can be used without damaging plastics materials.
Right bottom: A Britains model tractor from the 1960s has PVC tyres, not rubber as they appear. Phthalate plasticizer has migrated out of the back tyre and into the polystyrene wheel. The back wheel has the consistency of chewing gum.
The causes of instability include poor manufacturing practices, exhaustion or loss of stabilizing additives and inappropriate environment for use or storage. Early plastics, such as cellulose nitrate and acetates produce corrosive acidic gases. Phthalate plasticizers used to soften poly (vinyl chloride), migrate into adjacent materials or evaporate, leaving the PVC polymer itself vulnerable to deterioration. |
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Developing suitable inhibitive conservation techniques |
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Right: By ageing samples of plastics in different environments, including high relative humidity, with filtered air and without oxygen, accelerated by heat for several months, the rate of deterioration of plastics over years can be predicted.
This involves controlling the environments in which plastics are stored and displayed so that degradation reactions are slowed. Since heat, light, oxygen and moisture participate in plastics’ degradation processes, exposure should be minimized. It is important to tailor the storage environment to the individual plastics types.
Personnel working with Modern Synthetic Materials
Yvonne Shashoua, PhD, Senior Researcher
Mads Chr. Christensen, Head of Laboratory |
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