Abstract: Polymeric materials have considerably lower thermal stability than metals; most are flammable, but they can be formulated to be fire-resistant. They are good electrical insulators, have much lower modulus than metals, but higher strength-to-weight ratio; and exhibit viscoelastic behaviour, implying time dependence. In contrast with metals, polymeric materials exhibit creep effect, even at room temperature. According to their stress-strain behaviour, they can be divided into four classes: hard and brittle, hard and strong, hard and tough, and soft and tough. Polymers and plastics are generally resistant to alkalis, acids, and water but most are affected by certain organic solvents. Their outdoor weathering resistance varies from excellent to poor but most commercial plastics can now be compounded to show fairly good weathering performance. Chemical, electrical, and physical properties ( including mechanical properties) depend on the nature and amount of the various compounding ingredients.
Canadian Building Digest; no. CBD-157, ISSN:
0008-3097, Publication date:
1973
