Ultra-Thin interphase in Flax/Epoxy composites revealed by AFM PF-QNM nanomechanics
Year: 2026
Type: article
Abstract: • The existence of a transition zone at the fibre/matrix interface is investigated. • A near-field measurement technique is applied on a flax/epoxy composite. • Nanomechanical AFM mappings finely assess the elastic properties of the interphase. • An ultra-thin (around 80 nm) transition zone is observed and described. The fibre/matrix interface is a critical yet poorly understood feature of natural-fibre-reinforced composites, where load transfer and damage initiation are controlled. At the nanoscale, this boundary may evolve into an interphase, a narrow region with a gradient of mechanical properties, but its occurrence in bio-based systems remains unclear. Here, we use Atomic Force Microscopy in PeakForce Quantitative Nanomechanical Mapping mode (AFM-PF-QNM) to directly probe the nanoscale elastic modulus across flax/epoxy interfaces. Systematic mappings of multiple fibres reveal that, under the present conditions, an interphase is not consistently formed. When present, it is extremely thin (≈ 40–120 nm) and exhibits a distinct modulus gradient. These findings provide the first nanoscale evidence of the ultra-thin and irregular nature of interphase formation in flax/epoxy composites, challenging the assumption of a uniform and thick interphase in plant-fibre systems and offering new insights for interface engineering.
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,480
Funders: Agence Nationale de la Recherche, Centre National de la Recherche Scientifique, Conseil National de la Recherche Scientifique, Ministère de l'Enseignement supérieur, de la Recherche et de l'Innovation, Conseil régional de Bourgogne-Franche-Comté, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement
OpenAlex ID: W7126199893