 Polypropylene, PP, based composites are commonly reinforced with glass fibers, GF, but the polymer fiber interface is often weak and susceptible to environmental damage. In order to improve the adhesion between the two materials, researchers have attempted to modify the glass surface or the polymer matrix, but these approaches have not yielded significant cost performance improvements. A novel approach has been developed to increase the adhesion between PP and GF by polymerizing PP directly onto the fibers during manufacturing. This article was authored by Mariana Etcheverry and Sylvia Ibarbosa.