Plastics conservation

In conclusion, considerable progress has been made in the field of plastics conservation during the last 15 years. However, it is only with real-time ageing... 

Education in plastics conservation was initiated in the 1990s and the number of courses is growing steadily. Specialized, fuU-time courses for plastics conservators at undergraduate level would ensure that museums and other cultural institutes had qualified staff to conserve and research their collections. A combination of formal training and more practical internships involving conservation of plastics, particularly in contemporary art, modem history and medical collections, would equip conservators and conservation scientists with knowledge and experience of new materials. 

The need for knowledge about the conservation of plastics in cultural heritage is thus becoming increasingly important. Although a very substantial body of literature exists on the chemical, technological and manufacturing aspects of plastics, the scope of such books is too broad for conservation needs. Moreover, they often go into far too much depth to be directly useful for conservation purposes. On the other hand, the books which have been published until now about plastics conservation deal only with one or two plastic materials, and thus do not provide a total overview. 

The Conservation of Plastics provides important information on the definition of plastics, their history, technology, properties, identification, degradation, conservation and future preservation. Most importantly, it describes the state of the art of one of the newest fields in cultural heritage — plastics conservation. The information in this book is placed in context, and is illustrated with many examples that those involved in decision-making processes for conserving plastics objects will find helpful. This book will be present on every conservation table, in aU museums, training schools and universities, where it will be used on a daily basis. The beneficiaries will be the objects themselves plastics for everyday use, designer objects, furniture, toys and, most of all, modern and contemporary art. 

Plastics have short lifetimes compared with those of traditional materials found in museums, exhibiting deterioration within 5 to 35 years of acquisition. Deterioration and conservation of plastics olgects in museums has only been recognized formally as an area worthy of research since 1991. However, despite its novelty, the conservation of plastics is a rapidly developing field. A measure of the recognition of plastics conservation as a serious discipline was the creation of the working group Modern Materials and Contemporary Art (MMCa WG) by the International Council of Museums Committee for Conservation in 1996. 

W. Kaminsky, J. Menzel and H. Sinn, Recycling of plastics. Conservation Recycling, 1976,1,91-110. 

W Kaminsky, J Menzel, H Sinn. Int J Recycling Plastics Conservation and Recycling 1 91, 1976 J Anal Appl Pyrolysis 38 75-87, 1996 JS Kim, W Kaminsky, B Schlesselman. J Anal Appl Pyrolysis... 

If we load a material in compression, the force-displacement curve is simply the reverse of that for tension at small strains, but it becomes different at larger strains. As the specimen squashes down, becoming shorter and fatter to conserve volume, the load needed to keep it flowing rises (Fig. 8.6). No instability such as necking appears, and the specimen can be squashed almost indefinitely, this process only being limited eventually by severe cracking in the specimen or the plastic flow of the compression plates. 

Within the elastic regime, the conservation relations for shock profiles can be directly applied to the loading pulse, and for most solids, positive curvature to the stress volume will lead to the increase in shock speed required to propagate a shock. The resulting stress-volume relations determined for elastic solids can be used to determine higher-order elastic constants. The division between the elastic and elastic-plastic regimes is ideally marked by the Hugoniot elastic limit of the solid. 

With certain plastics, particularly high performance RPs, there can be two or three moduli. Their stress-strain curve starts with a straight line that results in its highest E, followed by another straight line with a lower E, and so forth. To be conservative providing... 

Since plastics are generally made from hydrocarbon feedstocks they should be recycled to conserve energy. The most effectives energy conservation is to refabricate plastic items, though this is not always technically feasible. Under circumstances where recycling is not a feasible option the use of plastics in waste-derived fuels may be an acceptable conservation measure. 

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