The effect of carbon fiber content on physico-mechanical properties of recycled poly(ethylene terephthalate) composites additively manufactured with fused filament fabrication

The combination of recycled fiber reinforcement with recycled polymer as a feedstock material for extrusion-based additive manufacturing creates an opportunity for a more sustainable material use. In this study, recycled short carbon fibers were combined with recycled poly(ethylene terephthalate) (PET) to obtain carbon fiber-reinforced PET filaments via melt extrusion. The carbon fiber content of the extruded filaments ranged from 0.4 to 40.7 wt%. The molar mass and the degree of crystallinity after processing were determined to evaluate the influence of the extrusion process on the physico-chemical and mechanical properties of the reinforced PET filaments. Furthermore, pressure-volume-temperature measurements were carried out to investigate the influence of the carbon fibers on the shrinkage of the semi-crystalline PET. Samples were printed and their superior mechanical properties, including a 390% increase in tensile modulus, were confirmed via tensile testing. Analysis via X-ray micro-computed tomography indicated that the fiber length reduced with increasing fiber content. The high degree of fiber alignment that was observed in the extruded filaments, was slightly reduced after deposition. Scanning electron microscopy data showed that fiber pull-out was the governing failure mechanism, indicating a weak interface between the carbon fibers and the matrix. The results show the potential of extrusion-based additive manufacturing to valorize recycled PET and recycled carbon fibers

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

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

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

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