plastic

plastic. Any of a large and varied class of artificial substances which are usually carbon-based polymers (i.e. with molecular structures made up largely or wholly from a great number of similar polyatomic bonded units) derived from synthetic resins or modified natural polymers, and with added substances giving colour and improved performance. They may be obtained in permanent or rigid form after moulding under pressure, extrusion. etc., when they are mouldable or liquid. Although discovered in C19 they were developed from the 1930s, and after the 1939–45 war (when they were employed for numerous purposes, notably in aircraft) were used in buildings for cladding, mouldings, pipes, gutters, etc. Plastics in building are of two general types: thermosets (incapable of being softened or melted by heat) and thermoplastics (which become soft when heated and rigid when cool, and can be repeatedly reheated and reshaped without any loss of their essential properties). In C20 certain plastics were used to create tensile structures (e.g. the work of Otto) and transparent polycarbonates for use in e.g. Fuller's geodesic domes, roofing, etc. Although capable of being formed into curved shapes (e.g. the tubes for the external escalators at the Centre Pompidou, Paris, by Piano and Rogers), transparent plastics, though tough, can be scratched, and can look very unsightly after a time. Plastics cause pollution during manufacture, so they are not favoured by advocates of Environmentally Responsible Architecture (they cannot be recycled and are difficult to dispose of), nor do those who argue in favour of traditional building methods approve of them (their appearance (not universally admired even when new) often deteriorates, and, in many cases, they have not lived up to expectations, have discoloured, or failed). However, plastics are widely used in protective coatings (e.g. paints), for electrical and plumbing systems, for insulation, and as waterproof sealants, gaskets, and membranes. Moulded plastic panels reinforced with glass-fibre (GRP) are used for walls and roofs. Whole buildings can be made from moulds on which liquid plastics are sprayed, and the material is being further researched as offering potential in architecture.

Bibliography

M. Foster (ed.) (1982);
T. Newman (1972);
Skeist (ed.) (1996);
Jane Turner (1996)