Sustainable Additive Manufacturing: Mechanical Response of Polypropylene over Multiple Recycling Processes

Abstract

The recycling of polymeric materials has received a steadily growing scientific and industrial interest due to the increase in demand and production of durable and lightweight plastic parts. Recycling of such materials is mostly based on thermomechanical processes that significantly affect the mechanical, as well as the overall physicochemical properties of polymers. The study at hand focuses on the recyclability of Fused Filament Fabrication (FFF) 3D printed Polypropylene (PP) for a certain number of recycling courses (six in total), and its effect on the mechanical properties of 3D printed parts. Namely, 3D printed specimens were fabricated from non-recycled and recycled PP material, and further experimentally tested regarding their mechanical properties in tension, flexion, impact, and microhardness. Comprehensive dynamic scanning calorimetry (DSC), thermogravimetric analysis (TGA), Raman spectroscopy, and morphological investigations by scanning electron microscopy (SEM) were performed for the different 3D printed PP samples. The overall results showed that there is an overall slight increase in the material’s mechanical properties, both in tension and in flexion mode, while the DSC characterization indicates an increase in the polymer crystallinity over the recycling course.

Optimization of the Filler Concentration on Fused Filament Fabrication 3D Printed Polypropylene with Titanium Dioxide Nanocomposites

“…The impact strength ( Figure 5 a) of the polymer was found to not be significantly affected by the filler’s concentration, although a similar trend to the other tests was observed. This agrees with the literature findings [ 8 , 24 , 32 ], which report that fillers have a low effect on the impact strength of polymers. A similar trend was observed for the microhardness measurements, with respect to the filler’s ratio ( Figure 5 b).…”

“…Additive manufacturing, and especially fused filament fabrication (FFF) technology, has great potential in the development of a sustainable society [ 7 ]. Relatively, research in AM has been conducted on recycling processes of polymers [ 8 , 9 , 10 , 11 ] and on mechanical, thermal, electrical and/or other property enhancements, using a wide variety of fillers and nanofillers dispersed in the polymer matrix [ 12 , 13 , 14 , 15 , 16 , 17 ].…”

Sustainable Additive Manufacturing: Mechanical Response of Polyamide 12 over Multiple Recycling Processes

“…Fused Filament Fabrication (FFF) is the most commonly used 3D printing AM method to date, especially for thermoplastic in nature polymeric materials, mainly due to characteristics, such as rapid processing, simplicity and cost-efficiency [10,11]. Research is available but limited regarding the recycling of thermoplastics by repetitive melt extrusion cycles and consecutive 3D FFF printing, while basically studies exist only for the most commonly used thermoplastics in FFF such as acrylonitrile butadiene styrene (ABS) [12] and polypropylene (PP) [13].…”

Design of an Atypical Construction of Equipment for Additive Manufacturing with a Conceptual Solution of a Printhead Intended for the Use of Recycled Plastic Materials

“…In the beginning, the excess and non-gift material was recycled and processed into a filament. This process has proven efficient but relatively lengthy and inefficient due to the production batch [32,33]. Due to this fact, the design was extended by the creation of an effector with a separate extrusion mechanism integrated directly into it.…”