Polymer-matrix composites have become an increasingly important class of materials in recent years to produce lightweight, high-performance parts and structures. For years graphene has been known to provide excellent reinforcement to polymer composite materials. However, composites incorporating graphene have yet to be commercialized due to the high costs and poor quality of commercially available graphene. A recently developed method for producing graphene, flash joule heating, promises to change this. Using this technique, large batches of high-quality graphene can be made in seconds. This thesis contains two primary studies:​ 1) a literature review on the quality, environmental outlook, and manufacturing of graphene and graphene-reinforced composites, and 2) the production, properties, and characterization of flash graphene reinforced thermoplastic composites of impact-copolymer polypropylene, polyamide 6, and isotactic polypropylene.