Blending of PLA and TPU in a Single Screw Extruder to Create 3D Printing Filament

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Publication Date

Spring 2021


3D printing has become of interest to the plastics industry to mainstream manufacturing because it can significantly increase the speed and reduce the cost of part production compared to traditional manufacturing methods for small production runs in the plastics industry. Poly lactic acid (PLA) is a hard, strong thermoplastic material that is processed in several different ways, including extrusion for 3D printing filament. Given its rigid nature, adding thermoplastic polyurethane (TPU), which is highly elastic, will improve filament flexibility while maintaining the desirable physical properties from PLA in a blended filament despite the two being immiscible with each other. Initial blending of the two materials was performed on a single screw Yellow Jacket extruder. PLA and TPU were blended in the following ratios: 100% PLA/0% TPU, 90% PLA/10% TPU, 70% PLA/30% TPU, 50% PLA/50% TPU, 30% PLA/70% TPU, 10% PLA/90% TPU, and 0% PLA/100% TPU by weight. Extrusion process parameters were adjusted until consistent filament diameters were achieved. The filaments were then analyzed by TGA and DSC for thermal properties and tensile testing for mechanical properties. The blend ratio by weight of 70% PLA/30% TPU and 50% PLA/50% TPU were found to have the most uniform diameters compared to the other ratios. The thermal analysis from TGA and DSC showed little thermal degradation after processing and the mechanical testing showed promising results for use as 3D printing filament.


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