Characterization of Optimized Ternary PLA/PHB/Organoclay Composites Processed through Fused Filament Fabrication and Injection Molding

Abstract

The aim of this study was to investigate the structure–properties relationship of ternary blends of polylactide/polyhydroxybutyrate (PLA/PHB)/organo-modified layered silicate (OMLS). Morphological, thermal, rheological, and mechanical characterizations were performed to understand the influence of OMLS on PLA/PHB (70/30 wt%) formulations optimized through modifications with an epoxy-based chain extender, the use of a plasticizer, as well as the influence of the type of processing route: injection molding or fused filament fabrication. The addition of OMLS allowed the blend compatibility to be improved, with the appearance of a single melting peak on DSC thermograms at 146 °C, as well as the reduction in the size of the nodules for the injected molded specimens. Concerning the printed samples, AFM analysis revealed a coalescence of the PHB minor phase due to its degradation. This phenomenon was dramatically enhanced in the presence of OMLS and has been ascribed to the degradation of both the organo-modifier and the PHB minor phase in the blend. Rheological and mechanical tests (17% decrease in Young’s modulus and 13% decrease in elongation at break) confirmed this degradation that would have occurred during the manufacturing of the filaments and the printing of specimens due to additional thermal and cooling steps.

Fabrication of poly(lactic acid), poly(butylene succinate), and poly(hydroxybutyrate) bio‐based and biodegradable blends for application in fused filament fabrication‐based 3D printing

“…The crystallinity of PBS/PHB and PBS/PLA blends was calculated by using Equation (): where W f is the weight fraction of the second component (PBS, PHB, and PLA) in the blend, ∆ H is the experimental crystallization enthalpy (J/g) of polymer in the blend, and ∆ H 0 was the melting enthalpy for 100% crystalline polymer taken from the literature. The value of is 110.3 J/g, is 93.7 J/g, and is 146.0 J/g 37–39 …”

“…The value of ΔH 0 PBS is 110.3 J/g, ΔH 0 PLA is 93.7 J/g, and ΔH 0 PHB is 146.0 J/g. [37][38][39] SEM was performed on Hitachi Tabletop Microscope TM3000 (Japan). The fractured surface was prepared in liquid nitrogen.…”

A thermoanalytical insight into the composition of biodegradable polymers and commercial products by EGA-MS and Py-GC-MS

“…The identification of sebacic acid di(3-butenyl) ester at 18.7 min and of 1,6diisocyanato-hexane at 14.7 min could be due to the presence of additives. In detail, di(3-butenyl) ester of sebacic acid could be a pyrolysis product derived from dibutyl sebacate, a known plasticizer added to polymeric blends to improve processability [71], [72]. 1,6-diisocyanato-hexane could be a chain extender used in the synthesis of PBAT as previously reported in the list of organic additives extracted from a PBAT mulch film [62].…”