Improving Mechanical Properties for Extrusion-Based Additive Manufacturing of Poly(Lactic Acid) by Annealing and Blending with Poly(3-Hydroxybutyrate)

Abstract

Based on differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, polarizing microscope (POM), and scanning electron microscopy (SEM) analysis, strategies to close the gap on applying conventional processing optimizations for the field of 3D printing and to specifically increase the mechanical performance of extrusion-based additive manufacturing of poly(lactic acid) (PLA) filaments by annealing and/or blending with poly(3-hydroxybutyrate) (PHB) were reported. For filament printing at 210 °C, the PLA crystallinity increased significantly upon annealing. Specifically, for 2 h of annealing at 100 °C, the fracture surface became sufficiently coarse such that the PLA notched impact strength increased significantly (15 kJ m−2). The Vicat softening temperature (VST) increased to 160 °C, starting from an annealing time of 0.5 h. Similar increases in VST were obtained by blending with PHB (20 wt.%) at a lower printing temperature of 190 °C due to crystallization control. For the blend, the strain at break increased due to the presence of a second phase, with annealing only relevant for enhancing the modulus.

Morpho-Structural, Thermal and Mechanical Properties of PLA/PHB/Cellulose Biodegradable Nanocomposites Obtained by Compression Molding, Extrusion, and 3D Printing

“…where ∆H m is the total melting enthalpy, ∆H cc is the cold crystallization enthalpy of PLA, w PLA and w PHB correspond to the weight fractions of PLA and PHB in the samples while ∆H m 0 represents the theoretical melt enthalpy of a fully crystalline PLA (93.0 J g −1 ) and PHB (146 J g −1 ) [40].…”

“…Morphological aspects of the cryo-fractured cross-sections of PLA/PHB nanocomposites as films and filaments were investigated by SEM and the images are shown in Figure 3a-d. PLA and PHB are semi-crystalline polymers. PHB has a higher crystallinity and can act as a nucleating agent to induce PLA crystallization into a more ordered crystalline structure [40]. PLA/PHB/NC-C film shows an irregular fractured surface with PHB crystalline domains embedded in an amorphous PLA continuous phase (Figure 3a) due to the partial compatibility of PLA and PHB [13,41].…”

Evaluation of the Suitability of Poly(Lactide)/Poly(Butylene-Adipate-co-Terephthalate) Blown Films for Chilled and Frozen Food Packaging Applications

“…It can be easily processed with conventional process such as extrusion, spinning, injection and compression molding [12][13][14][15]. However, its high brittleness limits its use, thus different strategies are tested in order to improve its toughness [16][17][18][19]. Among them, blending of PLA with PBAT has shown promising results.…”

3D Printing On-Water Sports Boards with Bio-Inspired Core Designs

“…However, structural complexity has rendered these composites challenging to manufacture.3D printing, or additive manufacturing (AM), refers to producing objects from a 3D model, mostly layer by layer. The main benefits of 3D printing could be listed as design freedom, waste diminution as well as the ability to fabricate complex structures with sufficient geometrical precision [12,13,[16][17][18][19][20]. Recently, studies have been conducted to take advantage of 3D printing in the field of sports.…”