Mechanical properties and design with rubber. General mechanical properties of polymers; viscoelasticity, time and temperature dependence, creep, recovery and stress relaxation. Design using deformation data; creep curves, pseudo-elastic design methodology, time and temperature dependant modulus, limiting strain. Mathematical modelling of viscoelasticity; equations for creep, recovery, relaxation, Maxwell and Voigt models, 4-element model, standard linear solid model. Boltzmann superposition principle and its use with complex stress histories. Strength and fracture of polymers; energy approach, toughness, ductile / brittle transitions, yield strength, ductility factor. Creep failure of plastics; fracture mechanics approach, fatigue failure, effects of cycle frequency, waveform, fracture mechanics approach to fatigue.