PSI - Issue 68

Robert Lowe et al. / Procedia Structural Integrity 68 (2025) 173–183 R. Lowe et al. / Structural Integrity Procedia 00 (2025) 000–000

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Fig. 7. Mode II interlaminar fracture toughness of flax fibre composites with PPS veils.

3.3. Flexural properties The flexural strength and modulus of the flax fibre composites with and without the addition of PPS veils are evaluated. Five samples are tested for each condition. Fig. 8 Summarize the test results. The introduction of PPS veils regardless of density has increased both the flexural strength and modulus of the composite over the reference samples. The addition of PPS veils with an areal density of 20 g/m 2 resulted in the largest increase in both properties, improving the strength and modulus of the composite by 15.5% and 21.8% respectively. Compared to the reference, both PPS5 and PPS10 also saw improvements in flexural strength of 9.7% and 6.3% respectively. With the addition of veils of areal density 5 g/m 2 the flexural modulus of the samples was improved by 17.3% while 10 g/m 2 resulted in a comparatively reduced increase of 13.3%.

Fig. 8. Flexural strength and modulus of composites with varying PPS areal densities.

From the bar plot, PPS10 is a clear outlier, while there appears to be a clear trend associated with the other values of improving properties with increased areal density of PPS, this trend does not apply to PPS10. Through linear interpolation of the results for PPS5 and PPS20, it is clear that the expected values of both properties for PPS10 would be extremely close to those generated for PPS5. Based on the standard deviations associated with each sample, it would be well within the bounds of statistical probability that a lesser value could be achieved. Similarly, the flexural