(351b) 3D Printing of a Recycled Terephthalic Acid-Based Copolyester Containing Tetramethylcyclobutanediol

Fused deposition modeling (FDM) is an important class of additive manufacturing that offers scalability and thermoforming of complex designs using thermoplastic matrices. A terephthalic acid-based polyester containing tetramethylcyclobutanediol (TMCD) diol monomer³ was recycled by 3D printing for the first time. The rigidity of cyclobutane ring in TMCD provides higher impact strength and glass transition temperature compared to other terephthalic acid copolyesters. The printing processes were optimized and materials were characterized for mechanical strength, thermal behavior, morphology and polymer structure. We found that bed temperature near ~100 °C was important for adhesion of first layer to the printing bed. The tensile strength, Young's modulus and notched Izod impact strength of the printed sample were 44 MPa, 4.2 GPa and 16.4 kJ/m²,respectively. Glass transition temperature of the copolyester was 103 °C. Weight-average molecular weight decreased from 38 to 32 kDa on recycling by 3D printing. ¹H, ¹³C, ¹H-¹H COSY and ¹H-¹³C HSQC NMR showed that fine structure was not altered by high temperature in 3D printing. We also performed micro-computed tomography (µCT) to see the voids among roads and layers in printed composites. The utilization of this copolyester for making 3D printed parts can increase recycling and the printed parts have properties that are suitable for making commercial products.