Recycling of polypropylene-based composites

The potential of recycling polypropylene-based composites by means of a dissolution process was investigated. The composites were dissolved in an appropriate solvent, and subsequently the polymer solution, containing the fibers in suspension, was filtrated for recovery of the reinforcing agent and of the polymer matrix. Different amounts of hot solvent were employed for washing during filtration, to vary the polymer content remaining on the fibers. The recycled fibers were incorporated in the same polymer matrix, but of virgin quality. The results on the tensile and impact performance of these second generation composites were compared to those of the base material containing unused fibers. It becomes evident that a significant increase of the tensile modulus and strength occurs as the polymer phase deposited on the fibers increases. However, it appears that this interphase alteration has a negative effect on the Izod impact strength. The overall behavior is discussed in terms of fiber dispersion aspects and fiber/matrix adhesion. © 1997 John Wiley & Sons, Inc. Adv in Polym Techn 16; 313–322, 1997