Cure

A controlled period at elevated temperature applied after a resin has initially hardened, driving the crosslinking reaction closer to completion. Post-curing raises the glass transition temperature and improves mechanical and chemical properties, and is routine for epoxy laminates and structural bonded assemblies.

The formation of chemical bonds between polymer chains, tying them into a three-dimensional network. It is the reaction underlying thermoset cure and determines rigidity, chemical resistance and the inability of cured resins to be re-melted.

The time taken for a mixed resin to change from a workable liquid to a soft gel that can no longer be applied or moved. It marks the practical end of the working period and is quoted by resin suppliers at a stated temperature and catalyst addition.

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.

The heat released by a thermosetting resin as it cures. In thick sections or large mixed volumes the temperature rise can be severe enough to cause discolouration, cracking or degradation, so laminate thickness per pass and mixing quantities are managed to control it.