ABSTRACT
Electrical conductivity is not normally a constraint in structural design, but thermal conductivity and thermal expansion are important, for example, in the fabric of a building and when estimating diurnal or seasonal expansion and contraction. This chapter briefly considers electrical conductivity since it provides a basis for the more complex ideas of thermal properties. The thermal conductivity of non-metals is more complex still, since it involves energy transfer between the atoms, which make up the material. Thermal expansion of a material is the result of increased vibration of the atoms when they gain thermal energy. As with the thermal conductivity, the coefficient of thermal expansion depends on the ease with which the atoms can move from their equilibrium position. Although the bonding within the chains of polymers is covalent and therefore strong, the secondary bonds between the chains are often weak leading to higher coefficients, typically of the order of 10-5 K-1.
