Work

Quasi-static mechanics of reactively formed epoxy–thermoplastic interphases in CFRP laminates

Year: 2026

Type: article

Abstract: This study compares amorphous PEI, PES, PSU, and PC films co-cured as functional interlayers in aerospace-grade CFRP laminates based on HexPly® M18/1. A unified quasi-static test matrix comprising single lap shear, interlaminar shear strength, and Mode I and Mode II fracture toughness was applied to establish a directly comparable mechanical ranking. All interlayer systems preserved structural integrity, increasing single-lap shear strength by 6.2% to 13.3% to about 16 to 18 MPa. Interlaminar shear strength remained in a range of 48 to 59 MPa, but depended on interlayer placement. Fracture testing revealed two distinct response types. PEI and PES showed the most effective toughening, with PEI reaching the highest Mode I toughness at 590 J/m² (+59.0%) and PES the highest Mode II toughness at 6180 J/m² (+518.6%). In contrast, PSU and PC showed poor opening-mode resistance. Overall, the results demonstrate that interlayer selection governs both the fracture mechanism and achievable damage tolerance.

Source: Advanced Manufacturing Polymer & Composites Science

DOI: 10.1080/20550340.2026.2657611

Authors: Matthias Taubert, Andreas Erich Scherer, Bruno Musil, Philipp Höfer

Institution: Universität der Bundeswehr München

Language: English

Topic: Mechanical Behavior of Composites

Subfield: Mechanics of Materials

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,060

Funder: Universität der Bundeswehr München