Dielectric Characterisation of Sisal Fibre Reinforced Polypropylene Composites

Sisal fibre reinforced Polypropylene (PP) composites were produced by compression moulding using fibres of different lengths, weight fractions, and surface treatments. Response Surface Methodology (RSM) was used to design the experiments, and the dielectric constant of the produced composites was measured at 10 Hz, 100 Hz, 1 kHz, and 10 kHz. The dielectric constant of polypropylene was in the range of 2.2-2.4 across all frequencies considered in this work. The results of ANOVA revealed that fibre loading was an important factor and contributed to 56.5% of all the variations in the dielectric constant. SEM analysis of the composite samples confirmed uniform fibre dispersion, supporting the dielectric results. The composites with untreated fibres had a higher dielectric strength than that of the treated fibres and polypropylene. The results of the experiments indicate that sisal/PP composites can be used as a sustainable dielectric material, especially for low-frequency insulation and energy storage applications. Major Findings: ANOVA confirmed that fibre loading was the most significant factor (56.5% contribution). Composites with untreated Sisal fibres showed higher dielectric constants (above 5.0 at 10 Hz for 30% loading) compared to neat polypropylene (2.2-2.4).