Direct Pellet Three-Dimensional Printing of Polybutylene Adipate-co-Terephthalate for a Greener Future

Abstract

The widespread use of conventional plastics in various industries has resulted in increased oil consumption and environmental pollution. To address these issues, a combination of plastic recycling and the use of biodegradable plastics is essential. Among biodegradable polymers, poly butylene adipate-co-terephthalate (PBAT) has attracted significant attention due to its favorable mechanical properties and biodegradability. In this study, we investigated the potential of using PBAT for direct pellet printing, eliminating the need for filament conversion. To determine the optimal printing temperature, three sets of tensile specimens were 3D-printed at varying nozzle temperatures, and their mechanical properties and microstructure were analyzed. Additionally, dynamic mechanical thermal analysis (DMTA) was conducted to evaluate the thermal behavior of the printed PBAT. Furthermore, we designed and printed two structures with different infill percentages (40% and 60%) to assess their compressive strength and energy absorption properties. DMTA revealed that PBAT's glass-rubber transition temperature is approximately -25 °C. Our findings demonstrate that increasing the nozzle temperature enhances the mechanical properties of PBAT. Notably, the highest nozzle temperature of 200 °C yielded remarkable results, with an elongation of 1379% and a tensile strength of 7.5 MPa. Moreover, specimens with a 60% infill density exhibited superior compressive strength (1338 KPa) and energy absorption compared with those with 40% infill density (1306 KPa). The SEM images showed that with an increase in the nozzle temperature, the quality of the print was greatly improved, and it was difficult to find microholes or even a layered structure for the sample printed at 200 °C.

Keywords: 3D printing; PBAT; biodegradable plastics; material extrusion; mechanical properties; nozzle temperature.

Figure 1

Material extrusion processes: (a) filament-based, (b) plunger or syringe-based, and (c) screw-based extrusion [29].

Figure 2

Printed tensile samples: (a) real samples and (b) standard dimensions (unit: mm).

Figure 3

Printed energy-absorption samples: (a) 60% infill density and (b) 40% infill density.

Figure 4

Energy absorption process (a) before the test, (b,c) during the test, (d) at the end of the test, and (e) after the test.

Figure 5

Dynamic mechanical thermal analysis results.

Figure 6

Tensile test results for different nozzle temperatures.

Figure 7

SEM images from interlayer adhesion for different nozzle temperatures: (a) 160 °C, (b) 180 °C, and (c) 200 °C.

Figure 8

SEM images from cavities and PBAT morphology for different nozzle temperature: (a) 160 °C (b) 180 °C and (c) 200 °C.

Figure 9

Stress–strain curves for 3D printed PBAT parts with 40% and 60% infill densities under compression loading.