Evaluation of the Technical Viability of Distributed Mechanical Recycling of PLA 3D Printing Wastes

Abstract

3D printing PLA wastes were recovered from a well-known reference grade and from different sources. The recovered wastes were subjected to an energic washing step and then reprocessed into films by melt-extrusion, followed by compression molding to simulate the industrial processing conditions. The obtained materials were characterized and the optical, structural, thermal and crystallization behavior are reported. The mechanical recycling process leads to an increase of the crystallinity and a decrease of the intrinsic viscosity of the formulations, particularly in the sample based on blends of different 3D-PLA wastes. Moreover, the obtained films were disintegrated under composting conditions in less than one month and it was observed that recycled materials degrade somewhat faster than the starting 3D-PLA filament, as a consequence of the presence of shorter polymer chains. Finally, to increase the molecular weight of the recycled materials, the 3D-PLA wastes were submitted to a solid-state polymerization process at 110, 120, and 130 °C, observing that the recycled 3D-wastes materials based on a well-known reference grade experiences an improvement of the intrinsic viscosity, while that coming from different sources showed no significant changes. Thus, the results show that 3D printing PLA products provides an ideal environment for the implementation of distributed recycling program, in which wastes coming from well-known PLA grades can successfully be processed in films with good overall performance.

Effect of Yerba Mate and Silk Fibroin Nanoparticles on the Migration Properties in Ethanolic Food Simulants and Composting Disintegrability of Recycled PLA Nanocomposites

“…As PLA cannot be infinitely recycled, due to each reprocessing cycle negatively affecting the thermomechanical properties of the PLA matrix [65,66], the recycled PLA-based materials after their useful life can be composted under industrial composting conditions in the same way as single-use PLA-based materials [67]. The degree of physical disintegration as a function of time was quantitatively monitored by the determination of samples' mass loss, as is shown in Figure 9.…”

Effects of Steam Heat and Dry Heat Sterilization Processes on 3D Printed Commercial Polymers Printed by Fused Deposition Modeling

“…It is also widely used in 3D printing processes, mainly due to its low glass transition temperature (58 °C) and low melting point (175 °C) [ 11 ]. In particular, PLA-based 3D printing materials have massively matured during the worldwide COVID-19 pandemic, which has allowed for the mitigation of the shortage of critical supplies in the fight against the pandemic (e.g., personal protective equipment (PPEs), medical devices, and testing devices) in the framework of a circular economy approach [ 15 , 16 , 17 ]. PLA filament for 3D printing can be found in a wide variety of compositions.…”

“…For the 3D-printing process, PLA does not require a high temperature in the printing bed (less than 60 °C), while the working temperature should be set between 195 °C and 220 °C [ 4 , 18 ]. Today, PLA is one of the most widely used sustainable polymers in many applications due to its biobased origin, biodegradable character, and recyclability [ 16 , 19 , 20 ]. However, PLA has high strength and stiffness, resulting in a brittle material.…”

Suitability of Recycled PLA Filament Application in Fused Filament Fabrication Process

“…After the print job is finished, support material can be mechanically removed or dissolved with appropriate solvent, but in most cases it is mechanically removed. As such, support material if not used in any other function after removal is waste material, but due to the nature of thermoplastics primarily used in AM, it can be recycled and reused in production of new products [3,4].…”