Optical Measurements of Shrinkage in UV-Cured Adhesives

This paper describes an optical method that has been developed to accurately measure shrinkage during the cure of adhesives treated with UV light. The experiment was designed to measure changes in the volume of very small quantities of material appropriate to uses in the fiber-optic and micro-electronic industries. A spot-curing device (EFOS Inc.) was used to deliver a controlled exposure of UV-light with a known distribution of wavelengths to the sample. The results indicate that reproducible values for the volumetric shrinkage can be achieved using spot-curing methods. The technique described in this paper, combined with other experimental measurements under development, will assist in the selection of the appropriate adhesive for specific applications and the curing conditions needed to optimize its final properties.