PSI - Issue 82

Jet Best et al. / Procedia Structural Integrity 82 (2026) 98–106

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J. Best et al. / Structural Integrity Procedia 00 (2026) 000–000

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Fig. 7. SEM images of Mode I fracture surface for reference sample: (a) 500x; (b) 1500x magnification and PES interleaved sample; (c) 500x; (d) 1500x magnification.

4. State of the Art The overall novelty of this work lies in testing the effect of interleaving PES films on a CF/EC IN2 epoxy composite. Interleaving films are often cited as a simple and effective method for improving CFRP ILFT. Production of polymer films is a simple process and doesn’t require much energy or sophisticated equipment. Most existing materials or techniques for enhancing interlaminar toughness are either costly and complex to implement or challenging to scale up. The present method is cost effective and scalable. PES films can be produced in bulk and stored ready for the composite manufacturing process. The carbon fibres and interleaving PES veils can be assembled during the composite fabrication stage, enabling this method to be easily scaled up on an industrial level. The quantity of PES required is minimal, making the method more competitive from the point of economic perspective. This study examines the applicability of this method to a standard room-temperature, vacuum-curing epoxy system. It was shown that significant modification of the resin curing procedure was required in attempts to achieve synergy between the PES interleaves and EC IN2 resin. This limits the potential applications of PES interleaves. They are not suitable for a composite system where room temperature curing is required. They are most applicable to a composite system designed specifically with their inclusion in mind, utilising a high-temperature curing resin, where they may provide further improvement to composite fracture properties than what is seen in this paper. 5. Conclusions This research studied the effect of interleaving PES veils on UD-CF reinforced EC IN2 epoxy polymer composites. PES interleaved composites showed a 24.7% increase in Mode I fracture energy compared to reference samples. SEM images revealed that reference samples failed by crack propagation to the fibre/matrix interface, with PES interleaves improving Mode I ILFT by constraining crack propagation to the interlaminar matrix region. ILSS exhibited an