Influence of Matrix Composition and MWCNT Incorporation on the Fracture and Failure Behavior of Polyamide‐Based Self‐Reinforced Composites

Abstract

The effect of matrix composition and filler incorporation on the fracture and failure behavior of polyamide/multi-walled carbon nanotubes (MWCNTs) self-reinforced composites (SRCs) obtained by film stacking followed by compression molding was investigated. Polyamide blends with different PA6/PA12 ratios (25/75, 50/50, and 75/25), with and without 3.5 wt.% MWCNTs, were used as matrices of the SRCs, while a PA6.6 plain-woven fabric was employed as reinforcement. The effect of consolidation temperature was also evaluated for one specific blend composition. Mechanical performance was assessed via uniaxial tensile, fracture, and quasi-static indentation tests, and acoustic emission analysis was also performed in situ during tensile tests. Results showed significant improvements in SRCs´ Young´s modulus (up to 100%) and tensile strength (up to 93%) over unreinforced matrices. MWCNT incorporation altered failure mechanisms, exhibiting enhanced ductility in indentation tests but generally reducing mechanical properties, while sometimes improving stiffness. Acoustic emission analysis confirmed a more progressive damage accumulation in MWCNT-containing composites. For the SRC with a 75/25 blend, a higher consolidation temperature (240°C) enhanced interfacial bonding and fabric integrity during failure, evidenced by a 40% reduction in cumulative acoustic events. These findings provide insights into the design of recyclable, lightweight, high-performance composites for the automotive and aerospace industries.