Graphite Modified Polylactide (PLA) for 3D Printed (FDM/FFF) Sliding Elements.

Robert E Przekop,Maciej Kujawa,Marta Dobrosielska,Wojciech Pawlak,Bogna Sztorch,Wojciech Wieleba

doi:10.3390/polym12061250

Abstract

With the development of 3D printing technology, there is a need to produce printable materials with improved properties, e.g., sliding properties. In this paper, the authors present the possibilities of producing composites based on biodegradable PLA with the addition of graphite. The team created composites with the following graphite weight contents: 1%, 2.5%, 5%, 7.5%, and 10%. Neat material was also subjected to testing. Tribological, mechanical, and chemical properties of the mentioned materials were examined. Measurements were also made after keeping the samples in ageing and climatic ovens. Furthermore, SEM observations of samples before and after friction tests were carried out. It was demonstrated that increasing graphite content caused a significant decrease in wear (PLA + 10% graphite had a wear rate three times lower than for a neat material). The addition of graphite did not adversely affect most of the other properties, but it ought to be noted that mechanical properties changed significantly. After conditioning in a climatic oven PLA + 10% graphite has (in comparison with neat material) 11% lower fracture stress, 47% lower impact strength, and 21% higher Young’s modulus. It can be certainly stated that the addition of graphite to PLA is a step towards obtaining a material that is low-cost and suitable for printing sliding spare parts.

Highlights

With the development of 3D printing technology, there is a need to produce printable materials with improved properties, e.g., sliding properties
A lot of spread material arranged parallel to the direction of cooperation was observed on the surface of the sample with a content of 10% graphite. It appears that a layer containing compressed and spread wear products appeared on the surface
The collected data has shown that prints made of PLA with the addition of graphite were characterized by significantly lower wear rate

Summary

Introduction

With the development of 3D printing technology, there is a need to produce printable materials with improved properties, e.g., sliding properties. The authors present the possibilities of producing composites based on biodegradable PLA with the addition of graphite. It was demonstrated that increasing graphite content caused a significant decrease in wear (PLA + 10% graphite had a wear rate three times lower than for a neat material). PLA + 10% graphite has (in comparison with neat material) 11% lower fracture stress, 47% lower impact strength, and 21% higher Young’s modulus. It can be certainly stated that the addition of graphite to PLA is a step towards obtaining a material that is low-cost and suitable for printing sliding spare parts. FDM uses thermoplastic polymers as the building material. One of the most commonly used materials in FDM is polylactide, since it adheres well to the printer bed during printing, requires a relatively low temperature of the printer bed and extruder, has a relatively low thermal shrinkage and does not emit harmful substances during printing

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Discussion

Conclusion