An overview of recycling issues for composite materials

A review of the major issues surrounding the post-use disposal of polymer composite materials is presented. Composites are compared to unreinforced plastics in terms of production volume and the technologies available for reprocessing. Not surprisingly, composites comprise a very small fraction of the plastics waste stream. In high-volume applications such as automobiles, however, there are reasons to be concerned about composites recycling. The fundamental categories of dealing with waste (burning, burying, reusing, or using less in the first place) are described in relation to plastics and composites. Reprocessing technologies with applications for composites are reviewed. For thermoset-matrix composites, processes involving regrinding waste materials and using them as filler for other polymer processes show promise. For thermoplastic-matrix composites, processes involving grinding and remolding by injection or compression molding are promising. Applications for recycled composites, without which reprocessing is futile, are also reviewed.