# Understanding the Role of PBAT Content and Raster Orientation on the Mechanical Performance of Material Extrusion 3D-Printed PLA/PBAT Objects

## TL;DR

This study explores how adding PBAT to PLA and changing print orientation affects the strength of 3D-printed objects.

## Contribution

The study introduces a novel evaluation of how PBAT content and raster orientation jointly affect the mechanical performance of 3D-printed PLA/PBAT blends.

## Key findings

- Increasing PBAT content and raster angle reduced tensile strength and modulus.
- PBAT improved impact strength, with the highest value at 40 wt.% PBAT and ±45° raster orientation.
- Raster orientation significantly influenced mechanical performance along with PBAT concentration.

## Abstract

Poly(lactic acid) (PLA) is the most widely used feedstock in material extrusion (MEX) 3D printing. In this study, PLA was combined with 0–40 wt.% of poly(butylene adipate-co-terephtalate) (PBAT) to improve its ductility. The resulting blends were processed into filaments suitable for MEX 3D printing and used to fabricate specimens for mechanical characterization using three distinct raster angles (RAs; 0°, ±45°, and 90°) to statistically evaluate the individual and joint effects of blend composition and raster orientation. Melt flow index (MFI) measurements showed that increasing PBAT content reduced the MFI from 40.4 g/10 min to 34.4 g/10 min, which led to weaker bonding between printed beads, as shown in scanning electron microscopic images. Tensile strength, modulus, and impact strength were evaluated using tensile and Charpy tests. Statistical analysis showed that RA, PBAT concentration, and their interaction all significantly influenced (p < 0.05) mechanical performance. Both strength and modulus decreased as PBAT content and RA increased, with the highest values of 50 MPa and 2.78 GPa observed for neat PLA 3D-printed at 0° RA, and the lowest values of 15 MPa and 1.05 GPa for 40 wt.% PBAT at 90° RA. In contrast, incorporating PBAT improved impact strength, showing its toughening effect. Meanwhile, no clear trend between impact resistance and RA was observed. The highest impact strength (52.7 kJ/m2) was found at 40 wt.% PBAT content and ±45° RA.