In English

PLA compounds for manufacturing of fossil-free filaments for 3D printing

Linnea Jonsson
Göteborg : Chalmers tekniska högskola, 2019. 53 s.
[Examensarbete på avancerad nivå]

The two polymers most widely used in 3D printing are acrylonitrile butadiene styrene (ABS) and polylacic acid (PLA). It is of great importance to reduce the use of the fossil-based ABS by substituting it with a material with less environmental impact, such as the bio-based PLA. The brittleness of PLA is however a drawback that limits the use of the material. The aim of this master’s thesis is to obtain PLA-based compounds, suitable for 3D printing, with enhanced properties which makes it possible to replace, at least to some extent, fossil-based filaments. From evaluating the state of the art it was concluded that thermoplastic poyurethane (TPU) and acetyl tributyl citrate (ATBC) are additives that can reduce the brittleness of PLA. Five different compounds (PLA,PLA+2%ATBC, PLA+2%TPU,PLA+5%TPU and PLA+12%TPU) were produced by extrusion and their properties were characterized using DSC, capillary viscometry, impact test and tensile test. All compounds showed transition temperatures similar to pure PLA and suitable viscosity at the shear rates used in 3D printing. With respect to the transition temperatures of the compounds and their viscosity, all the compounds are potentially suitable filaments for 3D printing. The addition of 2% ATBC and 2% TPU did not improve the impact strength or the properties obtained from the tensile test significantly. The impact strength was improved by the addition of 5% and 12% TPU and the tensile test showed that these compounds increased the elongation at break and decreased Young’s modulus, which indicates that these compounds are more ductile than pure PLA. It can therefore be concluded that PLA+5%TPU and PLA+12%TPU are the compounds investigated in this project that could be suitable to use as 3D printing filaments. Additional investigations, in particular of the morphology and miscibility of the compounds, are however necessary to verify the results and to further understand the properties of the compounds.

Nyckelord: Polylactic acid (PLA), bio-based compounds, thermoplastic polyurethane (TPU), acetyl tributyl citrate (ATBC), 3D printing, FDM.



Publikationen registrerades 2019-06-10. Den ändrades senast 2019-06-10

CPL ID: 256716

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