4D printing and annealing of PETG composites reinforced with short carbon fibers

Abstract

In this study, for the first time, post-heat treatment was applied to improve the stress recovery of short carbon fiber reinforced PETG (SCFRPETG). PETG and SCFRPETG composite were printed under optimal conditions, and constrained and free shape memory cycles were applied under compression and three-point bending loadings to assess shape and stress recovery. The results of the free shape memory test for both vertical and horizontal patterns showed that PETG composite also has a higher shape memory effect (SME) compared to PETG. The SME was significantly improved by performing heat treatment. The stress recovery values for pure PETG, reinforced PETG before and after annealing are 2.48 MPa, 3.04 MPa and 3.18 MPa, respectively. It showed that the addition of 1.5% carbon fiber increases the stress recovery by 22%. The increasing trend reaches 28% by performing post-heat treatment. Additionally, altering the printing pattern affects the programming and stress recovery values. For the SCFRPETG composite samples before and after annealing, changing the printing pattern from horizontal to vertical, resulted in a 16% and 7% increase in recovery stress, respectively. SEM results confirm that the annealing process removes the layered structure, micro-holes caused by shrinkage and 4D printing mechanism. Using the controlled heat treatment method can be a practical solution to solve the problem of adhesion and reduce the anisotropy of FDM 3D printed layers.

Supercritical Impregnation of PETG with Olea europaea Leaf Extract: Influence of Operational Parameters on Expansion Degree, Antioxidant and Mechanical Properties

“…On the other hand, the filament obtained at 250 bar and 35 °C with a similar antioxidant loading showed a high expansion degree (80%) and different mechanical performance ( TS value = 7.4 MPa, E value = 283.4 MPa, ε value = 5%). This result may be counterbalanced using short carbon fiber-reinforced PETG filaments, which have demonstrated superior stress recovery [ 6 ]. However, although the mechanical properties are far from those of the control filament, they are still comparable to polymeric vascular stents like the PLA/PCL (poly(lactic acid)/poly(ε-caprolactone)) 70/30 mixture, with TS values ranging from 2 to 4.5 MPa, PC (polycarbonate) with E values of 200–240 MPa, and elongation at break like PLLA (poly(L-lactid acid)) and PLGA (poly(lactic-co-glycolic acid), with values of 2–6% [ 61 ].…”

“…Furthermore, it is inexpensive and recyclable. In the literature, some articles were found using PETG as a novel thermoplastic thermo-responsive shape memory polymer [ 4 , 5 , 6 ], for the fabrication of 3D medical implants such as for maxillofacial bone reconstruction [ 7 ], and as a potential material for bone scaffolds using a filament-based extrusion additive manufacturing system [ 8 ]. However, scarce reports were found proposing PETG as a medical or drug delivery device loaded with bioactive compounds.…”

A U-Net-based self-stitching method for generating periodic grain structures

“…It is not limited to the grain structure but can be used for many porous structures, and even more structures with statistical homogeneity. It should also be able to extend to 3D systems for practical processes such as additive manufacturing [30,31]. In any case, the mask width should be essential, which may rely on the characteristic length of the dominant features.…”

Electrical/thermal triggering on shape memory composite tubes with different braiding angles

“…Additive manufacturing (3D/4D-printing) enables the preparation of complex structures (e.g. tubes, corrugations, and honeycombs) without inplane interweaving [24,25]. It cannot fully replace traditional manufacturing methods due to challenges for surface finish and mechanical properties of 3D-printed parts [26].…”