Influence of carbon fiber reinforcement on the shape memory characteristics and mechanical properties of PETG
Viswanath Aditham, Alfred James, Yanika Schneider, Sohail Zaidi, Vimal K. Viswanathan
Vol. 20., No.10., Pages 974-989, 2026
DOI: 10.3144/expresspolymlett.2026.72
DOI: 10.3144/expresspolymlett.2026.72
Corresponding author: Vimal K. Viswanathan 
GRAPHICAL ABSTRACT
ABSTRACT
Four-dimensional (4D) printing enables additively manufactured components to undergo programmed shape change, yet applications remain limited by the trade-off between shape-memory behavior and mechanical strength. In the study, we compare shape-memory PETG (SMP-PETG) and carbon fiber–reinforced PETG (CF-PETG), the latter containing a manufacturer- reported 10–15% chopped carbon fiber region localized within the filament core. We fabricated specimens by fused deposition modeling (FDM) using different nozzle temperatures and layer heights, and performed tensile, thermal and cyclic shape recovery tests to establish structure–property–function relationships within the PETG family. DSC showed predominantly amorphous behavior in CF-PETG, whereas SMP-PETG exhibited cold crystallization and melting features consistent with a crystallizable fraction in that commercial formulation. CF-PETG also showed a higher glass transition temperature than SMPPETG, indicating different thermal activation windows for the two materials. SMP-PETG exhibited ductile tensile behavior, with a peak strength of 25.69 MPa at 255°C and a layer height of 0.3 mm, and retained more stable shape recovery, with about 10–15% degradation over 50 cycles. In contrast, CF-PETG showed a steeper tensile response and higher strength, approaching 29 MPa, but less stable recovery, with losses of about 20–25% over the same cycle range. These findings characterize the combined effects of commercial formulation, reinforcement and processing; isolating the specific influence of core-localized reinforcement architecture will require comparisons with compositionally matched neat PETG and uniformly reinforced CF-PETG.
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