# Ternary Blends of PLA with ATEC and TMC-200 as Medical-Grade Biodegradable Monofilaments for FDM 3D-Printing Applications

## TL;DR

This paper introduces a new flexible and biocompatible PLA filament for 3D printing by blending it with ATEC and TMC-200, improving its mechanical properties and printability.

## Contribution

The study presents a ternary blend of PLA with ATEC and TMC-200 that enhances flexibility, tensile strength, and biocompatibility for medical-grade 3D printing.

## Key findings

- PLA blended with 3.0 wt% ATEC and 0.3 wt% TMC-200 achieved 232% elongation at break and 35.0 MPa tensile strength.
- The ternary blend increased crystallinity from 4.7% to 45.0% and showed over 99% cell viability in L929 fibroblasts.
- PLA/T/A monofilaments retained mechanical and thermal performance after FDM printing and 8 weeks of shelf-life testing.

## Abstract

Poly(L-lactide) (PLA) is a promising biopolymer for biomedical applications due to its biodegradability and biocompatibility; however, its brittleness restricts its use in fused deposition modeling (FDM). To overcome this limitation, flexible PLA monofilaments with enhanced mechanical performance and printability were developed. In this study, PLA was melt-blended with acetyl triethyl citrate (ATEC, 1.0–5.0 wt%) as a plasticizer and zinc phenyl phosphonate (TMC-200, 0.3 wt%) as a nucleating agent. It was found that the PLA with 3.0 wt% ATEC (PLA/A) exhibited the greatest flexibility, while the addition of TMC-200 further improved tensile strength and ductility. Specifically, the ternary blend of PLA/TMC-200/ATEC (PLA/T/A) exhibited a synergistic effect, achieving superior mechanical properties (tensile strength: 35.0 MPa, elongation at break: 232.0%, compared to 12.1% for pure PLA) and raising the degree of crystallinity (Xc) from 4.7% to 45.0%. Monofilaments (1.70 ± 0.05 mm) fabricated from PLA/T/A exhibited smooth surfaces, balanced mechanical performance, and excellent cytocompatibility (over 99% cell viability in L929 fibroblasts). Moreover, FDM-printed specimens retained enhanced mechanical and thermal performance, demonstrating material stability after processing. Shelf-life testing further confirmed the structural integrity of PLA/T/A monofilament after 8 weeks at 50 °C. Overall, PLA/T/A provides an effective strategy for producing high-performance, medical-grade PLA monofilaments with improved toughness, printability, and biocompatibility, enabling their application in biomedical 3D printing.