Sustainable Additive Manufacturing: Mechanical Response of High-Density Polyethylene over Multiple Recycling Processes

Vidakis, Nectarios; Petousis, Markos; Maniadi, Athena

doi:10.3390/recycling6010004

Cited by 42 publications

(17 citation statements)

References 24 publications

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“…The literature reports developments in sustainable additive manufacturing by studying the mechanical and thermal behavior of Acrylonitrile Butadiene Styrene (ABS) in FFF and after repeated heating cycles and extruded material reprocessing [4,5]. The literature also reports similar studies with Polypropylene (PP) [6], and Polyethylene (PE) (with the brand name Kritilen, procured from its manufacturer Plastika Kritis S.A., Heraklion, Greece) [7]. Moreover, studies on FFF and the mechanical properties of 3D printed parts report that 3D printing parameters can directly affect the mechanical properties of the final part [8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

MEX 3D Printed HDPE/TiO2 Nanocomposites Physical and Mechanical Properties Investigation

et al. 2022

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Aiming to develop more robust, mechanically advanced, Fused Filament Fabrication (FFF) materials, High-Density Polyethylene (HDPE) nanocomposites were developed in the current research work. Titanium Dioxide (TiO2) was selected as filler to be incorporated into the HDPE matrix in concentration steps of 0.5, 2.5, 5, and 10 wt.%. 3D printing nanocomposite filaments were extruded in ~1.75 mm diameter and used to 3D print and test tensile and flexion specimens according to international standards. Reported results indicate that the filler contributes to increasing the mechanical strength of the virgin HDPE at certain filler and filler type concentrations; with the highest values reported to be 37.8% higher in tensile strength with HDPE/TiO2 10 wt.%. Morphological and thermal characterization was performed utilizing Scanning Electron Microscopy (SEM), Raman, Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC), while the results were correlated with the available literature.

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Section: Introductionmentioning

confidence: 99%

MEX 3D Printed HDPE/TiO2 Nanocomposites Physical and Mechanical Properties Investigation

et al. 2022

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“…HDPE is a linear polymer that can be processed by many common melt-processing means, for instance, through injection molding or extrusion [ 101 ]. HDPE is the second-most recycled plastic, and the ability to recycle HDPE in additive manufacturing, through FFF, has been demonstrated [ 102 , 103 ].…”

Section: Approaches Used For the Additive Manufacturing Of Polyolefinsmentioning

confidence: 99%

Additive Manufacturing of Polyolefins

2022

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Polyolefins are semi-crystalline thermoplastic polymers known for their good mechanical properties, low production cost, and chemical resistance. They are amongst the most commonly used plastics, and many polyolefin grades are regarded as engineering polymers. The two main additive manufacturing techniques that can be used to fabricate 3D-printed parts are fused filament fabrication and selective laser sintering. Polyolefins, like polypropylene and polyethylene, can, in principle, be processed with both these techniques. However, the semi-crystalline nature of polyolefins adds complexity to the use of additive manufacturing methods compared to amorphous polymers. First, the crystallization process results in severe shrinkage upon cooling, while the processing temperature and cooling rate affect the mechanical properties and mesoscopic structure of the fabricated parts. In addition, for ultra-high-molecular weight polyolefins, limited chain diffusion is a major obstacle to achieving proper adhesion between adjunct layers. Finally, polyolefins are typically apolar polymers, which reduces the adhesion of the 3D-printed part to the substrate. Notwithstanding these difficulties, it is clear that the successful processing of polyolefins via additive manufacturing techniques would enable the fabrication of high-end engineering products with enormous design flexibility. In addition, additive manufacturing could be utilized for the increased recycling of plastics. This manuscript reviews the work that has been conducted in developing experimental protocols for the additive manufacturing of polyolefins, presenting a comparison between the different approaches with a focus on the use of polyethylene and polypropylene grades. This review is concluded with an outlook for future research to overcome the current challenges that impede the addition of polyolefins to the standard palette of materials processed through additive manufacturing.

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“…In many cases, material degradation after multiple extrusion has also been considered for both single-screw extrusion and twin-screw extrusion. [8,11,[23][24][25][26][27][28][29][30][31][32][33] Here, among other factors, different screw speeds or screw configurations were investigated. Greater degradation was found with higher shear rates in the single-screw extruder [23] and with the increased use of kneading blocks on the twin-screw extruder.…”

Section: State Of the Artmentioning

confidence: 99%

Measurement of material degradation in dependence of shear rate, temperature, and residence time

Schall

Schöppner

2022

Polymer Engineering & Sci

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During processing, plastics are frequently exposed to high stresses. These include, above all, shear and temperature within the scope of the residence time of the manufacturing process in order to achieve a homogeneous plastic melt for further processing. The stress of the manufacturing process can lead to molecular degradation, which can have a negative effect on the product properties. Since it makes sense to take molecular degradation into account for many processes, a test stand for material characterization was designed and a regression equation was derived for the mathematical description of the degradation behavior. With the help of this regression equation, a prediction of the expected material degradation can be made, provided that the shear rate, the temperature and the associated residence time are known.

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Sustainable Additive Manufacturing: Mechanical Response of High-Density Polyethylene over Multiple Recycling Processes

Cited by 42 publications

References 24 publications

MEX 3D Printed HDPE/TiO2 Nanocomposites Physical and Mechanical Properties Investigation

MEX 3D Printed HDPE/TiO2 Nanocomposites Physical and Mechanical Properties Investigation

Additive Manufacturing of Polyolefins

Measurement of material degradation in dependence of shear rate, temperature, and residence time

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