Abstract: Chemical shrinkage in the process of resin curing will cause composite material defects and these defects can greatly reduce the performance of the composite materials. According to this article, through the improvement method which adds a contrast bottle to the traditional capillary dilatometer as well as the selection of PE bag, a fast, efficient, high precision and high applicability test method of chemical shrinkage was found. Based on the contact of chemical shrinkage and degree of cure, it has been confirmed that the chemical shrinkage was independent with the temperature and time except for appearing only a bilinear relation with degree of cure. Overall, the line′s slope starts to change when the degree of cure is about 0.28 (initial gel point). The earlier stage slope is about 42.54. The later stage slope is about 64.63. The general chemical shrinkage rate is 7.55% after being completely cured. It also suggests that the rates of chemical shrinkage is greater after resin gelation.

Key words: chemical shrinkage, degree of cure, capillary dilatometer, epoxy resins