In-situ foaming of polyvinylidene fluoride in extrusion-based additive manufacturing: Processing–structure relationship for lightweight structures

This work investigates the rheology, in-situ foaming behavior, and foam morphology of PVDF containing CBA for material-extrusion additive manufacturing. The addition of CBA significantly reduces melt viscosity by a factor of three to four at low shear facilitating improved flow and enabling printing at lower temperatures. Foaming trials identify viable processing window of 210–235 °C, within which withdrawn filament tips show consistent microcellular expansion; temperatures above 235 °C cause uncontrolled gas release and unstable extrusion. SEM analysis of printed samples reveals that foaming strongly depends on the interplay between nozzle temperature and layer height. Optimal foam morphology achieved at 225 °C and a 0.1-mm layer height, producing uniform cells with a void fraction of ∼39% and a high volumetric cell density (∼2.6 × 10 7 cm −3 ). TGA analysis provides insight into the thermal decomposition behavior of the chemical blowing agent and the temperature range of gas evolution. Overall, the study establishes key processing–structure relationships that enable stable, high-quality PVDF foams via extrusion-based 3D printing, significantly broadening the scope of lightweight design in demanding engineering environments.