Dynamic mechanical analysisDMA

The temperature region over which an amorphous or partly amorphous polymer changes from a rigid, glassy state to a softer, rubbery one. It sets a practical upper service temperature for resins and adhesives and can be reduced by absorbed moisture or incomplete cure.

A thermal analysis technique that measures heat flow into or out of a small sample as it is heated, cooled or held at constant temperature. For thermosets it reveals the glass transition temperature, residual exotherm and degree of cure; for thermoplastics it shows melting and crystallisation behaviour.

Material behaviour that combines viscous flow with elastic response, so that stiffness depends on time, loading rate and temperature. Polymers are viscoelastic, which gives rise to creep, stress relaxation and damping, and is characterised by dynamic mechanical analysis.