Tribology of 3D printed High Strength Nanocomposite Polymer for Bio Application

Author(s): Alex Assadi

Mentor(s): Ali Beheshti, Mechanical Engineering

Abstract

Our summer research was focused on finding the best method for creating composite polymers to improve surface quality. To do this, we used Noztek extruder and a couple different mixing machines. We had four different mixing methods, and we used all of them to create PLA with 1% Hydroxyapatite by weight. The printer that was used for the research was a creatbot F160 and all samples were printed using the same parameters. After starting on creating the composites, we quickly realized that it was very challenging to create a PLA and HA composite that was not super brittle. The first samples were too brittle for printing, but after some time with the extruder, we were able to create some normal PLA and we got one sample. Currently we are still working on creating more composite filament, and we hope to have some samples by next week. In order to test these samples, the nanoindenter was used to find the main mechanical properties such as hardness or elastic modulus. Additionally, the profilometer was used to measure the profile of the surfaces and give back properties such as the roughness. 

Video Transcript

‘-fused deposition modeling or FDM printing has been around me since the 80,s and has become a great tool for rapid prototyping or even producing complex designs it works by feeding plastic filament through a “hot end” that extrudes it onto a print bed in 2D, it repeats this layer by layer creating a 3D object.  -whether it’s automotive, aerospace, biomedical, or even sports FDM printing has a ton of useful applications -there are many different types of FDM filament, one of the most popular is PLA which is seen on the left, some others are ABS, PETG, or Nylon which can be used in many different applications. -composite filament is normal filament with some other materials added to it. Two popular composites shown on the right are wood reinforced PLA, and carbon fiber reinforced PLA. These additives change the properties of the base polymers, and can be useful in different applications. -our research was focused on adding Hydroxyapatite to PLA using a couple different methods to see which had the best improvement on the surface properties. -the filament was created using a Noztek extruded as seen on the left. The PLA pellets and hydroxyapatite that was used to make the composite filament can be seen to the right of this.  -in the top right corner is a picture of the speed mixer which was used for two of the mixing methods to create the PLA/HA composite. The magnetic stirrer which was another method can be seen below that, the last method was combining the PLA and HA and directly extruding it multiple times. -to test our results, we used the nano indenter which can be seen on the left, this gave us important mechanical properties that could be compared to other research. On the right is another machine we used, the profile meter, this is used to measure the surface profile of the samples and give properties such as roughness back. -unfortunately we had some challenges when creating the composite that resulted in it being very brittle and difficult to print. Because of this, we only got the one PLA sample which can be seen below. Nevertheless, I learned a lot through this research and it was a great experience. 

One reply on “Tribology of 3D printed High Strength Nanocomposite Polymer for Bio Application”

Great job explaining how your research works, Alex. Will you modify the “mixture” of the materials in the composite to decrease brittleness? What is the next step to generate enough material for testing? Tissue hydroxyapatite is also pretty brittle, as I understand it. Thank you for sharing your work. Dr. Lee

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