Breaking Through the 3D Printing Material Bottleneck! Modification and Process Parameters of PLA/PBS/PBAT/CaCO₃
With the development of the plastics industry, environmental pollution is becoming increasingly serious, and the demand for environmentally friendly materials is growing. Although biodegradable materials are environmentally friendly, they suffer from limited performance and a narrow range of applications. While blending different biodegradable materials can leverage their respective strengths, they face the challenge of poor compatibility between the materials, necessitating the addition of modifiers.
Professor Wang Yan and graduate student Yin Mengxiao from the School of Materials Science and Engineering at Wuhan University of Technology studied the application of biodegradable materials PBS and PBAT as matrix materials in fused deposition modeling (FDM) 3D printing. PBS/PLA (polylactic acid), PBAT/nano-CaCO₃, and PBAT/PBS blends were prepared by melt blending. These blends were then modified with a coupling agent, MDI (4,4'-diphenylmethane diisocyanate), and an epoxy chain extender, ADR, to produce 3D-printable biodegradable composites. The mechanical, thermal, and degradation properties of the composites and their 3D-printed samples were systematically investigated. The influence of FDM process parameters on the mechanical properties of the printed samples was also explored. The specific conclusions are as follows:
1. Research on PBS and Its Blends
Performance and Printing Process of Pure PBS: Pure PBS has high fluidity, making it difficult to draw into wire, as it requires rapid cooling. The performance of PBS-printed samples gradually improved with increasing printing temperature and infill density, but decreased with increasing printing speed. When the process parameters were a printing temperature of 170°C, a printing speed of 40 mm/s, an infill density of 70%, and a print layer thickness of 0.2 mm, the tensile strength increased by 55.02% compared to injection molding.
Modification and Properties of PBS/PLA Blends: The addition of PLA improved the rigidity of the PBS. With increasing PLA content, the flexural strength, flexural modulus, Vicat softening temperature, and hardness of the blend increased, while the elongation at break and melt flow rate (MFR) decreased. The addition of MDI improved the mechanical properties of the blend and significantly enhanced the compatibility between the components, making it more suitable for the preparation of printing filaments. The PBS/PLA/MDI blend achieved the best overall mechanical properties when the process parameters were a printing temperature of 260°C, a printing speed of 20 mm/s, an infill density of 100%, and a print layer thickness of 0.2 mm.
Degradation Performance: Enzymatic degradation assays revealed 180-day degradation rates of 70.32% for pure PBS and 54.27% for PBS/PLA/MDI composites; soil burial assays revealed degradation rates of 30.22% and 4.15%, respectively.
2. Research on PBAT and Its Composite Materials
Pure PBAT Performance and Printing Process: Pure PBAT is relatively soft, requiring high printing temperature, low printing speed, and 100% infill density to produce dense samples. When the process parameters were 290°C, 20 mm/s, 100% infill density, and 0.2 mm layer thickness, the tensile strength increased by 20.94% compared to injection molding.
Modification and Performance of PBAT/Nano-CaCO₃ Composites: Adding 10 wt.% nano-CaCO₃ increases the composite's rigidity and reduces printer requirements. When the process parameters are a printing temperature of 220°C, a printing speed of 20 mm/s, a fill density of 100%, and a layer thickness of 0.2 mm, the PBAT/nano-CaCO₃ composite achieves optimal comprehensive mechanical properties, with flexural strength and modulus increasing by 53.47% and 49.88%, respectively, compared to pure PBAT printed samples.
Degradation Performance: The 180-day degradation rates of pure PBAT and the composite, as measured by the soil burial method, were approximately 32.82% and 25.77%, respectively. Enzymatic degradation methods measured the degradation rates to be approximately 64.05% and 52.52%, respectively.
3. Research on PBAT/PBS Blends
Blend Modification and Performance: Adding 20 wt.% PBS significantly improved the mechanical properties of the blend. Adding 0.6 wt.% ADR chain extender significantly improved material compatibility and reduced the system's requirements for printing equipment. The mechanical properties of the printed samples were optimized when the process parameters were a printing temperature of 270°C, a printing speed of 20 mm/s, a fill density of 50%, and a layer thickness of 0.2 mm.
Degradability: The 180-day degradation rates of the PBAT/PBS/ADR blend were approximately 6.17% and 64.38%, respectively, measured by soil burial and enzymatic degradation methods.
4. Future Research Focus
While science and technology continue to advance, environmental issues persist, and the need to develop new biodegradable materials persists. Melt blending to prepare materials with different ratios to screen for suitable composite materials is a current research hotspot in the field of biodegradable materials. Combining this with 3D printing technology can expand the application of biodegradable materials. Future research may focus on the following areas:
Optimizing modifier application: Comparing different types of modifiers, adjusting modifier content, and improving the compatibility of the various components in the blend system, fully leveraging the advantages of each component in the system, and further enhancing the overall performance of the material.
Optimizing FDM process parameters: In-depth adjustment of various FDM process parameters to ensure excellent performance of printed samples while reducing time and material costs, thereby improving 3D printing efficiency and cost-effectiveness.
Designing the internal structure of the material: Designing an appropriate internal structure of the material ensures that the sample meets the required strength and achieves rapid degradation, balancing practicality and environmental protection, and promoting the application of biodegradable materials in more applications.
