Influence of machine type and consecutive closed-loop recycling on macroscopic properties for fused filament fabrication of acrylonitrile-butadiene-styrene parts

Abstract

Purpose This study aims to evaluate and compare the macroscopic properties of commercial acrylonitrile-butadiene-styrene (ABS) processed by two different types of additive manufacturing (AM) machines. The focus is also on the effect of multiple closed-loop recycling of ABS. Design/methodology/approach A conventional direct-drive, Cartesian-type machine and a Bowden, Delta-type machine with an infrared radiant heating system are used to manufacture test specimens molded in ABS. Afterward, multiple closed-loop recycling cycles are conducted, involving consecutive AM (four times) and recycling (three times). The rheological, mechanical, morphological and physicochemical properties are investigated. Findings The type of machine affects the quality of the produced parts. The machine containing an infrared radiant system in a temperature-controlled chamber produces parts showing higher mechanical properties and filling fraction, although it increases the yellowing. Closed-loop recycling of ABS for AM is applicable for at least two cycles, inducing a slight increase in tensile modulus (ca. 5%) and in tensile strength (ca. 13%) and a decrease in the impact strength (ca. 14%) and melt viscosity. An increase in the filling fraction of the AM parts promotes an increase in tensile strength and tensile modulus, although it does not influence the impact strength. Furthermore, multiple closed-loop recycling does not affect the overall chemical structure of ABS. Practical implications Controlling the environmental temperature and using infrared radiant heating during AM of ABS improves the quality of the produced parts. Closed-loop recycling of ABS used in AM is feasible up to at least two recycling steps, supporting the implementation of a circular economy for polymer-based AM. Originality/value This study shows original results regarding the assessment of the effect of different types of AM machines on the main end-use properties of ABS parts and the influence of multiple closed-loop recycling on the characteristics of ABS fabricated by the most suited AM machine with an infrared radiant heating system and a temperature-controlled environment.

A Combined Experimental and Modeling Study for Pellet-Fed Extrusion-Based Additive Manufacturing to Evaluate the Impact of the Melting Efficiency

“…Printing employing polymer pellets leads to a lower cost of the final material [ 20 ] and, due to the higher possible melting rate [ 19 ], a faster processing speed for, in principle, a wider range of materials is realized [ 20 ]. It allows us to bypass the filament extrusion process that normally precedes the AM process, relieving the material of one extrusion cycle, leading to less degradation [ 27 ].…”

Up-Cycling of LCD Glass by Additive Manufacturing of Porous Translucent Glass Scaffolds

“…Future optimization studies will undoubtedly involve MSLA, but not exclusively; in fact, in DIW-processing, besides in the formulation of inks, multiple adjustments may arise from modification in the choice of nozzles [ 37 ] or slicing sequence [ 38 ], as well as in the same concept of machine (classic direct-drive, Cartesian-type printer, instead of the adopted delta-type printer) [ 39 ]. Additional efforts are envisaged in the development of analytical models to predict the structural mechanical behavior of printed parts, with fundamental attention to changes in printing patterns, as already done for polymers and polymer-based composites [ 40 , 41 , 42 , 43 ].…”

Comparing pellet‐ and filament‐based additive manufacturing with conventional processing for ABS and PLA parts

“…In any case, degradation is a parameter to be investigated in polymer processing with various results being reported, either on the molecular 32,33 or the macroscopic (or final product) level. 24,34,35 For example, oxidative degradation for poly(lactic acid) PLA films manufactured by SSE 34 can lead to a decrement in the strain at break as well as more brittle behavior that has been linked to a reduction of the average molar mass in the oxidation process. Beltran et al in turn 24 studied for PLA films the effect of accelerated aging through UV and heat exposure, observing a decrement in the average molar mass, while the modulus of the material remained nearly unchanged.…”

“…This has been specifically illustrated by Fernandez et al, 31 who highlighted that a switch from “Digital ABS” to Polyamide 11 can be useful for AM insert production for hybrid molding applications. In any case, degradation is a parameter to be investigated in polymer processing with various results being reported, either on the molecular 32,33 or the macroscopic (or final product) level 24,34,35 . For example, oxidative degradation for poly(lactic acid) PLA films manufactured by SSE 34 can lead to a decrement in the strain at break as well as more brittle behavior that has been linked to a reduction of the average molar mass in the oxidation process.…”

“…Beltran et al in turn 24 studied for PLA films the effect of accelerated aging through UV and heat exposure, observing a decrement in the average molar mass, while the modulus of the material remained nearly unchanged. Furthermore, a study on acrylonitrile butadiene styrene polymer (ABS) 35 observed that additional treatments can lead to an increment in the tensile modulus and tensile strength as well as a decrease in the impact strength.…”