Incorporation of vitamin E in poly(lactic acid) filaments: a 3D printing study

Poly(lactic acid) (PLA) is a promising biopolymer for additive manufacturing applications. Antioxidants are commonly used in polymer industry to prevent thermo-oxidative degradation, and vitamin E is an option from renewable sources. A mixture of PLA and vitamin E, at concentrations of 0, 0.25, 0.50, 0.75, and 1 wt%, was prepared in the torque rheometer at 200 °C. The production of the filaments for 3D printing was conducted in a single-screw extruder. The materials were characterized using the Melt Flow Index (MFI), Thermogravimetry (TGA), Differential Scanning Calorimetry (DSC), and Oxidative Induction Time (OIT) methods. 3D-printed parts were analyzed using Fourier Transform Infrared Spectroscopy (FTIR), parallel plate rheometry, and colorimetric analysis. The results indicated that adding vitamin E did not affect the material’s melt flow index (MFI), despite decreasing its complex viscosity and modifying its storage and loss modulus. Furthermore, incorporating vitamin E at concentrations of up to 0.75 wt% helped the material resist thermal degradation, as evidenced by the thermogravimetric analysis results. Regarding the antioxidant properties of the modified material, the OIT test revealed that a concentration of 0.5 wt% provided the best stability. Additionally, colorimetric analysis showed no significant variation for vitamin E concentrations above 0.75 wt% in the polymer.