Searching for Rheological Conditions for FFF 3D Printing with PVC Based Flexible Compounds

Area of Science:

• Materials Science
• Polymer Science
• Additive Manufacturing

Background:

• Plasticized poly(vinyl chloride) (PVC) is a promising material for flexible 3D printed objects using fused filament fabrication (FFF).
• Understanding the rheological behavior of PVC is crucial for successful FFF processing and achieving desired object properties.
• Previous studies have not fully explored the link between rheology and FFF performance for flexible PVC.

Purpose of the Study:

• To investigate the rheological properties of plasticized PVC formulations for FFF.
• To determine the viscoelastic factors influencing the success or failure of FFF with these materials.
• To establish optimal printing conditions for producing flexible and ductile objects via FFF.

Main Methods:

• Rheological analysis, including small amplitude oscillatory shear (SAOS) measurements.
• Investigation of the relaxation modulus G(t) and the G″/G' ratio.
• Filament buckling analysis based on compression modulus and viscosity under nozzle conditions.

Main Results:

• PVC formulations exhibit a crystallite network causing nozzle clogging, which disappears only at high temperatures risking thermal degradation.
• Analysis of the relaxation modulus G(t) proved more effective than the G″/G' ratio for assessing layer welding quality.
• Optimal printing conditions were established, leading to the successful fabrication of flexible and ductile models.

Conclusions:

• Rheology is a critical tool for optimizing plasticized PVC for FFF applications.
• The crystallite network in PVC presents challenges for FFF, necessitating careful control of printing temperature and rheological parameters.
• This study marks a significant advancement in producing high-quality, flexible 3D printed objects using PVC via FFF.