Comprehensive Analysis of <scp>3D</scp> Printed <scp>PETG</scp> ‐ <scp>LDPE</scp> Composites: Structure–Property Relationship and Shape Memory Behavior

ABSTRACT Regarding the inferior mechanical performance and physical characteristics of low‐density polyethylene, this study explores the development and characterization of LDPE and PETG with varying PETG concentrations (55 wt.%, 70 wt.%, and 85 wt.%) to evaluate their shape memory properties, stress relaxation, thermal analysis and printing ability. Tensile testing revealed significant variations in mechanical performance, with strength increasing by 37%, from 17.04 MPa for PETG55 to 23.42 MPa for PETG85. DMTA highlighted PETG's dominant influence on the composites' thermomechanical behavior, with the glass transition temperature peaking at approximately 87°C. Shape memory testing demonstrated fixity ratios of 92%–93% for all compositions and recovery ratios ranging from 86% to 96%, with the highest recovery ratio observed in PETG85. The behavior of the cyclic shape memory up to the fifth cycle shows a gradual decrease until the third pass and then a stabilization. SEM provided detailed insights into the composites' microstructure, revealing interfacial bonding quality, void formation, and phase distribution, characterized by a PETG matrix‐droplet morphology. This study establishes that higher PETG content enhances thermal stability, mechanical strength, and shape memory performance, while increased LDPE content contributes to improved stress relaxation and processing flexibility. These results position PETG‐LDPE composites as promising candidates for high‐performance applications in aerospace and industrial environments, particularly where shape memory behavior and tailored thermomechanical properties are required.