However, renewable sources will probably eventually be used and so polymer technology will have come full circle as the first synthetic polymers were made from naturally occurring sources. Recycling of synthetic polymer materials is a problem which is being addressed in several ways. Elastomers are also usually thermoplastics. In the building industry, synthetic polymers have not often been used in structural applications. This is because of the inherent conservatism of the building industry and cost factors rather than the properties of the materials themselves.
Plasticisers are usually organic compounds themselves, such as the phthalates.
These materials may have potential for unwanted effects on environmental or human health although considerable uncertainty remains. Sunlight degrades polymers and this effect may be exacerbated by heat and moisture. Stabilisers make polymers less prone to degradation either during manufacture or in use. These include compounds of cadmium, lead and other heavy metals as well as various complex organic compounds, the environmental impacts of which are either not known or not disclosed. Not surprisingly there has been a recent trend to to substitute more benign materials in polymer formulations.