Part materials for additive manufacturing applications include materials with a fluoropolymer processing aid (material-FP). These materials include one or more thermoplastic polymers and one or more fluoropolymers as a processing aid. The material-FP is used to build parts with additive manufacturing systems. Parts built using material-FP have improved physical properties including improved strength in the z-direction of the parts. Composite systems such as reinforced filaments with the material-FP also have a higher density.