Degradation Behavior of 3D-Printed Residue of Astragalus Particle/Poly(Lactic Acid) Biocomposites under Soil Conditions

Abstract

Astragalus is widely cultivated in China, and the residue of Astragalus particles (ARP) can be used as reinforcements in fused filament-fabricated (FFF) natural fiber/Poly(lactic acid)(PLA) biocomposites. To clarify the degradation behavior of such biocomposites, 3D-printed 11 wt% ARP/PLA samples were buried in soil, and the effects of soil burial duration on the physical appearance, weight, flexural properties, morphology, thermal stability, melting, and crystallization properties were investigated. At the same time, 3D-printed PLA was chosen as a reference. The results showed that, with prolonged soil burial, the transparency of PLA decreased (but not obviously), while the surface photographs of ARP/PLA became gray with some black spots and crevices; especially after 60 days, the color of the samples became extremely heterogeneous. After soil burial, the weight, flexural strength, and flexural modulus of the printed samples all reduced, and greater losses happened to ARP/PLA pieces than pure PLA. With an increase in soil burial time, the glass transition, cold crystallization, and melting temperatures, as well as the thermal stability of PLA and ARP/PLA samples, all increased gradually. Additionally, soil burial had a greater effect on the thermal properties of ARP/PLA. The results showed that the degradation behavior of ARP/PLA was more significantly affected by soil burial than the behavior of PLA. Additionally, ARP/PLA more easily degraded in soil than PLA.

FDM 3D Printing and Soil-Burial-Degradation Behaviors of Residue of Astragalus Particles/Thermoplastic Starch/Poly(lactic acid) Biocomposites

“…It was found that the sample lost its weight obviously with time: after being buried in soil for 180 days, the weight loss was 21.40%, indicating that the extension of soil-burial time would promote the biodegradation of ARP/TPS/PLA, which was consistent with the results from the visual appearance observation. Comparing the weight with that of pure PLA [ 21 ], it was found that ARP and TPS greatly accelerated the degradation of PLA.…”

“…Based on our previous work, 11 wt.% was the best proportion for ARP to add into PLA for the FDM 3D printing of ARP/PLA pieces when the cost and quality of the filament were taken into consideration simultaneously [ 21 ]. In this paper, the maximum proportion of ARP in the composite was thus controlled within 11 wt.%.…”

“…Samples were printed with filaments prepared with the formulations listed in Table 1 on a desktop-level 3D printer (MOSHU S10, Hangzhou Shining 3D Technology Co. Ltd., Hangzhou, China) fitted with a 0.4-mm die nozzle. The printing parameters were chosen according to those for the FDM 3D printing of ARP/PLA biocomposite samples [21] and listed in Table 2. The physical images of the printed samples are shown in Figure 1b.…”

Bio-Composite Filaments Based on Poly(Lactic Acid) and Cocoa Bean Shell Waste for Fused Filament Fabrication (FFF): Production, Characterization and 3D Printing

“…In this study, biofilaments comprising PLA and CBSW at varying concentrations were developed and used to produce 3D models by FFF, offering a novel approach to waste recycling and reuse through FFF printing. The findings highlight the feasibility of integrating waste materials into the production cycle while emphasizing the importance of sustainable practices in modern manufacturing [ 22 , 23 , 24 , 25 ]. Based on this scenario, the aim of this study was to develop and characterize biocomposite filaments made from poly(lactic acid) and 5–10 wt.% of cocoa bean shell waste for FFF printing technology, from a CE perspective.…”