Cellulose and polypropylene filament for 3D printing

Abstract: Additive manufacturing has become a very popular and well mentioned technique in recent years. The technique, where 3 dimensional (3D) printing is included, creates opportunities to develop new designs and processing systems. As a research institute within the forest based processes and products, Innventia AB has an idea of combining 3D printing with cellulose. The addition of cellulose will increase the proportion of renewable raw material contributing to more sustainable products. However, when cellulose is added the composition of the filaments changes. The main aim for the project is to devise methodologies to improve properties of composite filaments used for 3D printing. Filament in 3D printing refers to a thread-like object made of different materials, such as PLA and ABS, that is used for printing processes. A literature study was combined with an extensive experimental study including extrusion, 3D printing and a new technique that was tested including 3D scanning for comparing the printed models with each other. The extruding material consisted of polypropylene and cellulose at different ratios, and filaments were produced for 3D printing. The important parameters for extruding the material in question was recorded. Because the commingled material (PPC) was in limited amount, UPM Formi granulates, consisting of the same substances, was used first in both the extrusion and printing process. Pure polypropylene filaments were also created in order to strengthen the fact that polypropylene is dimensional unstable and by the addition of cellulose, the dimensional instability will decrease. After producing filaments, simple 3D models were designed and printed using a 3D printing machine from Ultimaker. Before starting to print, the 3D model needed to be translated into layer-by-layer data with a software named Cura. Many parameters were vital during printing with pure polypropylene, UPM and PPC. These parameters were varied during the attempts and marked down for later studies. With the new technique, in which 3D scanning was included, the 3D printed models were compared with the original model in Cura in order to overlook the deformation and shape difference. The 3D scanner used was from Matter and Form. Photographs of the printed models, results from the 3D scanner, and screenshots on the model in Cura were meshed together, in different angles, using a free application named PicsArt. The result and conclusion obtained from all three parts of the experimental study was that polypropylene’s dimensional stability was improved after the addition of cellulose, and the 3D printed models’ deformation greatly decreased. However, the brittleness increased with the increased ratio of cellulose in the filaments and 3D models.