Title 3D printing filaments from recycled polymer
Description of the technology

Currently, several principles of 3D printing are recognised for which procedures have gradually been developed and improved. The one in most common use is the Fused Filament Fabrication (FFF) or Fused Deposition Modelling (FDM) method. The principle of this method is that the filament is inserted into the nozzle and the resulting melt is applied onto the pad in several thin layers until a three-dimensional object of the desired shape and dimensions is created.

The materials used for filaments are predominantly polymeric materials differing in their mechanical and thermal properties (e.g. acrylonitrile butadiene styrene, polylactic acid, polyethylene terephthalate and others). In addition to polymeric materials, the filaments can also contain various additives (wood flour, ceramic particles, graphene, etc.) which serve to improve the mechanical properties or the appearance of the material. Their disadvantage is that they significantly affect the rheological properties of the melt or have abrasive effects on the nozzles which can lead to their wear and more frequent replacement. Recently, we succeeded in using recycled polyethylene terephthalate glycol as the polymer matrix of the material for 3D printing, which has a higher impact resistance and clarity than polyethylene terephthalate. As it is a recycled material, its price is several times lower than that of non-recycled polyethylene terephthalate. Furthermore, this is not reflected in the properties of the resulting 3D object. For the purposes of improving the mechanical properties (static and dynamic) and reducing the weight of the final product, we mixed carbon fibres in a suitable ratio with expanded graphite into this polymer matrix. Expanded graphite with lubricating effects also reduces the abrasive properties of carbon fibres, improves the rheological properties of the polymer melt with carbon fibres and adds a fine texture to the filaments, resulting in an easier feed into the nozzle. Thanks to the high thermal conductivity of the expanded graphite, it is not necessary to change the temperature parameters of the processing.

New polymer composites can be used in 3D printing, especially for the production of high-performance materials for the automotive industry.

Keywords 3D printing, filament, polymer composite, recycled polymer, graphite
Stage of Development Development from prototype to final product
Language of communication Slovak, English
Contact point Dr. Zdeno Spitalsky, Polymer Institute, Slovak Academy of Sciences, zdeno.spitalsky@savba.sk