Cure cycle design to suppress moisture-driven bubble growth in polymer composites

Abstract

This paper discusses how theories of moisture diffusion and bubble growth in liquid polymers can be used to determine the temperature and pressure conditions of the resin under which stable and unstable bubble growth is expected. The applicability of these bubble growth criteria is validated by videotaping bubble growth in moisture conditioned MTM 45-1 epoxy resin samples in-situ using a digital microscope. The bubble growth criteria are then used together with cure kinetics and viscosity models for the resin to design cure cycles that suppresses bubble growth for different moisture levels in the resin. The validity and applicability of the proposed cure cycle design approach are confirmed with experiments.