Abstract

Fast and eco-friendly composite curing technologies are highly sought after, and ultraviolet (UV) curing offers both features. UV curing can be applied as a bulk curing technology as long as light arrives at all the points in the material with enough intensity. Additionally, the outer layer cures almost instantaneously, reducing the emission of volatile organic compounds. Despite its benefits, the implementation of UV curing technology in composites manufacturing is still in an early stage, and more basic knowledge about its principles needs to be generated. For instance, when curing considerably thick laminates, the light arriving at the points in the material further from the exposed surface is insufficient for a one shot consolidation, requiring a layer-by-layer curing strategy.

In the present paper, we explore several approaches for the layer-by-layer curing of a glass fibre reinforced unsaturated polyester composite. We assessed the impact properties of the manufactured laminates through drop weight low velocity impact tests to quantitatively evaluate the different approaches. We found that the laminate cured in three steps, applying four plies by shot, had the best impact performance, followed by the composite cured in two steps. On the other hand, the laminate cured in one shot had the worst impact properties, dissipating 20% less energy than the best performing laminate. Therefore, we conclude that the bonding of the UV cured laminates is tough and that the residual stresses induced during manufacturing are lessened the thinner the layers cured in each step are.