Cure Shrinkage Characterization of a Thermosetting Resin with Three-Dimensional Digital Image Correlation (3D-DIC)

Abstract

This work presents the application of three-dimensional digital image correlation (3D-DIC) to capture pre- and post-gelation volumetric chemical shrinkage of EPON 862 thermosetting resin paired with hardener triethylenetetramine (TETA) and cured at room temperature. The manufacturer-recommended 100:14 resin-hardener mixing ratio is used for DIC experimentation. A stress-free boundary condition is employed with a thin Teflon sheet placed between the resin mixture and the specimen container. For the first time, a spray-painted speckle pattern is applied directly to the resin to record full-field strain measurements during curing. This speckle pattern is employed immediately after the resin mixture is poured on the Teflon-covered specimen container for the pre-gelation case, and after gelation has been visibly observed for the post-gelation case. Strain capture with 3D-DIC is initiated directly after speckle pattern application with stereo-images captured every 30 seconds for one hour and then every 60 seconds for two hours. Differential scanning calorimetry (DSC) is used to determine resin cure kinetics to correlate chemical shrinkage with degree of cure. The presented technique provides an innovative methodology to characterize the chemical shrinkage of thermosets during curing.