Development of Low-Cost Bio-Filled Additive Manufacturing Composite Feedstocks

Biomass fibers have been commonly used for reinforcing polymers (e.g., polylactic acid [PLA]) because of their low density, low cost, renewable nature, biodegradability, and abundance. In this study, pine/PLA composites were produced with a high loading (40 wt%) of pine fibers to reduce the composite feedstock cost for the additive manufacturing application. To improve composite performance, low-cost aspartic acid was incorporated. The aspartic acid loading was optimized, and the composites prepared were characterized to understand the effect of aspartic acid content on different composite properties using tensile testing, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and rheological testing. Results show that the Young’s modulus of the composites was improved by 30% with the addition of a small amount of aspartic acid (0.7 wt%). The coupling agent was found to be effective in tuning the properties of the composites for specific applications.