Investigation on the use of PLA/hemp composites for the fused deposition modelling (FDM) 3D printing

This work is a preliminary study about the use of hemp powder as filler in a biopolymer, i.e. polylactic acid (PLA), and the following use of such composites in the 3D printing via FDM technique. In particular, hemp powder (diameter between 75 and 180 μm) was added via melt-compounding into PLA 4043D at three different volume percentages (1, 3 and 5%). Rheological properties of the blends were determined using a rotational rheometer resulting in a decrease of complex viscosity at increasing hemp loading. PLA/hemp filaments (diameter of 2.85 mm) were produced using a single screw extruder. Dynamic mechanical analysis (DMA) on PLA/hemp filaments reported an increase of storage modulus at increasing hemp volume fraction, but compared to the neat PLA filament only the PLA+5%H blend has a higher storage modulus. Finally, filaments were used to print, using a commercial printer (Ultimaker 3, Netherlands), dog-bone specimens for tensile tests. PLA/hemp printed samples exhibited always higher elastic modulus than PLA specimens and it increases at increasing hemp content.