Printability, Mechanical and Thermal Properties of Poly(3-Hydroxybutyrate)-Poly(Lactic Acid)-Plasticizer Blends for Three-Dimensional (3D) Printing

Abstract

This paper investigates the effect of plasticizer structure on especially the printability and mechanical and thermal properties of poly(3-hydroxybutyrate)-poly(lactic acid)-plasticizer biodegradable blends. Three plasticizers, acetyl tris(2-ethylhexyl) citrate, tris(2-ethylhexyl) citrate, and poly(ethylene glycol)bis(2-ethylhexanoate), were first checked whether they were miscible with poly(3-hydroxybutyrate)-poly(lactic acid) (PHB-PLA) blends using a kneading machine. PHB-PLA-plasticizer blends of 60-25-15 (wt.%) were then prepared using a corotating meshing twin-screw extruder, and a single screw extruder was used for filament preparation for further three-dimensional (3D) fused deposition modeling (FDM) printing. These innovative eco-friendly PHB-PLA-plasticizer blends were created with a majority of PHB, and therefore, poor mechanical properties and thermal properties of neat PHB-PLA blends were improved by adding appropriate plasticizer. The plasticizer also influences the printability of blends, which was investigated, based on our new specific printability tests developed for the optimization of printing conditions (especially printing temperature). Three-dimensional printed test samples were used for heat deflection temperature measurements and Charpy and tensile-impact tests. Plasticizer migration was also investigated. The macrostructure of 3D printed samples was observed using an optical microscope to check the printing quality and printing conditions. Tensile tests of 3D printed samples (dogbones), as well as extruded filaments, showed that measured elongation at break raised, from 21% for non-plasticized PHB-PLA reference blends to 84% for some plasticized blends in the form of filaments and from 10% (reference) to 32% for plasticized blends in the form of printed dogbones. Measurements of thermal properties (using modulated differential scanning calorimetry and oscillation rheometry) also confirmed the plasticizing effect on blends. The thermal and mechanical properties of PHB-PLA blends were improved by the addition of appropriate plasticizer. In contrast, the printability of the PHB-PLA reference seems to be slightly better than the printability of the plasticized blends.

In vivo and Post-synthesis Strategies to Enhance the Properties of PHB-Based Materials: A Review

“…The optimum concentration could be up to 20% depending on the desired properties of the final products (Erceg et al, 2005 ; Râpe et al, 2015 ; Chaos et al, 2019 ). From the study of Choi and Park ( 2004 ), triethyl citrate was the most effective plasticizer in terms of reduction in the glass transition temperature as well as in terms of improvement in the impact strength and elongation.…”

“…Epoxidized oils are among the most studied plasticizers of PVC, obtained by epoxidation with peracids with various oils (Turco et al, 2019b ). The behavior in mixture with PHB can be explained by the higher reactivity of the epoxide group and the possibility of hydrogen bond formation (Choi and Park, 2004 ; Jost and Langowski, 2015 ; Panaitescu et al, 2017 ).…”

Realization of Circular Economy of 3D Printed Plastics: A Review

“…Figure 6 a–c show some recent research using PHB as 3D printing material. PHB can be copolymerized with 3-hydroxyvalerate to form poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) [ 36 , 37 ] or with PLA by co-blending modification [ 38 , 39 , 40 ] to get new 3D printing materials as shown in Figure 6 d. Through performance testing, these materials can be applied to in vivo scaffolds. Although PHB can be degraded by enzymes, thermal cleavage, photo-cracking, and other ways [ 41 ], there are still some disadvantages, such as slow degradation, high energy consumption of degradation, and impurity recovered material.…”

“… 3D printing of Poly β-Hydroxybutyric (PHB) and its degradation. ( a – c ) PHB 3D printing patterns [ 38 , 39 ]; ( d ) PHB 3D printing process [ 40 ]; ( e ) reusable result of [Bmim]FeCl 4 [ 42 ]. …”

FDM 3D Printed Composites for Bone Tissue Engineering Based on Plasticized Poly(3-hydroxybutyrate)/poly(d,l-lactide) Blends

“…To achieve this, we used the following materials: (i) poly(3-hydroxybutyrate) (PHB), the most published and commercially successful PHA polymer, which has all the above-mentioned features of PHA family; (ii) amorphous PLA, which contributes to the processability and mechanical properties of the resulting material; (iii) plasticizers varying in molecular weight and chemical structure to further improve overall properties and printability; and (iv) TCP to promote a good response of the materials in vivo. Our research group drawn from its unique experience with FDM 3D printing of PHB/PLA blends [33,34].…”