Issue 78

N. Nayak et alii, Fracture and Structural Integrity, 78 (2026) 378-392; DOI: 10.3221/IGF-ESIS.78.22

properties with fibre content or fibre length. Moderate fibre loading and appropriate fibre length promoted improved stress transfer, whereas excessive reinforcement reduced performance by causing poor dispersion, agglomeration and void formation. The reported regression equations can be used for prediction within the investigated design range, but extrapolation beyond this range should be avoided. Multi-response optimization should therefore select a balanced formulation that maximizes tensile, flexural and impact performance while retaining dielectric constant values close to polypropylene for insulating applications. Figs. 5–9 provide a graphical representation of the statistical models developed in this study. Fig. 5 illustrates the main effects of fibre length, fibre loading and fibre treatment on tensile, flexural and impact strengths. Fig. 6 shows the variation in dielectric constant with the investigated process variables and test frequency. The interaction plots presented in Figs. 7 and 8 help explain how combinations of these variables influence mechanical and dielectric responses. Fig. 9 presents the contour plots used to identify the processing conditions that provide a balanced combination of mechanical performance and dielectric behaviour.

Figure 5: Main effects plots for tensile, flexural and impact strengths.

Figure 6: Main effects plot for dielectric constant.

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