Effect of extrusion and fused filament fabrication processing parameters of recycled poly(ethylene terephthalate) on the crystallinity and mechanical properties

Abstract

The production of plastic has grown exponentially over the past few decades and with it the amount of plastic waste leaking in the environment, where it fragments into micro-and nanoplastics. This problematic situation stresses the need for increased plastic collection, recycling and reuse rates. Extrusion-based additive manufacturing (AM) and especially fused filament fabrication (FFF) offer an efficient and effective method to reuse and upcycle recycled plastic. This study focuses on poly(ethylene terephthalate) (PET), which has a broad application window and its recycling is therefore environmentally and economically favorable and sustainable. Therefore, this study involves the thermal and mechanical behavior of recycled PET after extrusion and 3D printing. The extrusion parameters are optimized by performing a complete physico-chemical and thermal analysis of the obtained filaments and they were compared with commercial virgin and recycled PET. Moreover, the influence of the applied processing conditions on the degree of crystallinity and mechanical properties is investigated. The filaments are then used for FFF, where various printing parameters are altered to obtain the optimum printing conditions (i.e. printing temperature, the build plate temperature, fan cooling and printing directions). The effect of the degree of crystallinity of semi-crystalline PET is investigated via altered printing parameters, showing superior mechanical properties for an increasing degree of crystallinity. To verify the portability of the obtained optimized print parameters, two different FFF printers are used. The use of recycled PET as feedstock for FFF supports the efforts for improving the sustainability of plastics by valorizing PET waste, and prolonging the lifecycle of PET.

Investigation of Polyester Tire Cord Glycolysis Accompanied by Rubber Crumb Devulcanization

“…The same raw material [9], or only crumb rubber [10], could be used as bitumen modifiers or reinforcement materials for expansive soils [11]. The newest application for recycled tire cord components is 3D printing using polyethylene terephthalate [12] or crumb rubber [13,14].…”

Blown Composite Films of Low-Density/Linear-Low-Density Polyethylene and Silica Aerogel for Transparent Heat Retention Films and Influence of Silica Aerogel on Biaxial Properties

“…A second heating method was performed at 300 °C at a similar scanning rate. The degree of crystallinity (X c ) was calculated from the peak area of the DSC thermograms [ 17 ]. The mechanical properties were evaluated using an Instron 5567 material testing system at 25 °C, as per the ASTM D638-96 type II requirements [ 18 ].…”

“…Billions of pounds of polymer are processed annually by using this technique. Blown film extrusion is used to produce agricultural and construction films, industrial films and bags, stretch films, polyvinyl chloride cling films, liners, high barriers, and small tube systems [ 16 , 17 ].…”

Feasibility Study on the Fused Filaments of Injection-Molding-Grade Poly(Ethylene Terephthalate) for 3D Printing

“…Plastic filaments using amorphous polymers are widely applied to facilitate additive manufacturing. Mechanical strength is acquired from semi-crystalline polymers, polyether ether ketone (PEEK) [ 10 , 11 ], an advanced engineering plastic, and PET [ 12 , 13 , 14 ]; these materials are, therefore, essential in medical, chemical, aerospace, and electronics applications using fused filament fabrication. PEEK is a thermoplastic biomaterial with good thermal resistance, stability, and mechanical properties.…”

“…However, the high cost of PEEK filament for 3D printing makes this material suitable only for valuable applications in bio-implants. Previous studies explored the recycling of polymeric materials for the production of filaments in 3D printing, such as PET, ABS, PLA, polypropylene (PP), nylon (PA), polystyrene (PS), polyethylene (PE), acrylonitrile styrene acrylate (ASA), polyvinylchloride (PVC), high-impact polystyrene (HiPS), polycarbonate, high-density and low-density polyethylene (HDPE, LDPE), and thermoplastic polyurethanes (TPU) [ 12 , 15 , 16 , 17 ]. The recycling phases for filament fabrication involve cleaning, grinding, melting, extrusion, and measuring.…”