Test MethodEvaluation of cure shrinkage measurement techniques for thermosetting resins

Resin chemical shrinkage dictates the surface integrity and the roughness of a composite structure. Thus, to minimize surface failures and to produce a good surface quality it is a requisite to be able to measure and track resin shrinkage during the cure process. This manuscript investigates and evaluates the measuring and monitoring of real-time resin shrinkage using a rheometer, a helium-based pycnometer and a thermo-mechanical analyzer (TMA) for ambient curing UP and epoxy resins. Shrinkage readings obtained from the newly developed robust technique with the rheometer concur well with readings from the traditional pycnometric method. They also coincide within the accepted literature values of 7-10% and 3.5-4.5% for the UP and epoxy systems, respectively. Shrinkage measurements during post-cure were effectively carried out at an elevated temperature, suggesting that the methodology provided can be applied to non-ambient curing systems. The TMA was found to be unsuccessful in measuring shrinkage reliably.