Fig. 9.

SEM images of uncoated PETG and uncoated PLA filament

(a) uncoated PETG filament: magnification 50×

white arrow points to one of several notches

(b) uncoated PLA filament: magnification 50×

white arrow points to one of several notches

(c) uncoated PETG filament: magnification 250×

(d) uncoated PLA filament: magnification 250×

(e) uncoated PLA filament: magnification 500×

* points to production-related elevation with a size of 40 μm

(f) uncoated PLA filament: magnification 1,000×

▲ points to calcium particles with sizes of 2–5 μm.