Waste sunn hemp fibres/epoxy composites: mechanical and thermal properties

Natural fibres have dominated synthetic fibres in recent years due to their easy availability, biodegradability and cost. In this work, sunn hemp waste fibres (SHF) were utilized to fabricate epoxy-based composites. Raw, 15% alkali-treated and 127% grafted SHF composites were prepared at 10%, 20% and 30% loadings, and their mechanical properties were evaluated. It was observed that at 30% loading for 127% grafted SHF, the values of highest tensile strength of 68.73 MPa, and the strength, impact strength, interlaminar shear strength and microhardness of 128%, 4.6 J, 68.9 MPa and 63%, were obtained in the order given. Chemical resistance was also found to be excellent for 127% grafted SHF at 30% loading. Similarly, the dynamic mechanical analysis indicated an increase in storage and loss moduli for grafted fibre composite and a decrease in tan delta for grafted SHF at 30% loading. Dimensional stability was excellent with respect to grafted 127% SHF composites. Scanning electron microscopy analysis proved superior bonding with grafted SHF composites followed by 15% alkali and raw composites. Vertical burning test showed that the grafted SHF composites with 30% loading took 490 s to completely drip down after burning. Chemical resistance and dimensional stability were also excellent for grafted SHF composites. Dimensional stability deteriorated with the use of benzyl alcohol solvent. Thermogravimetric analysis proved to be excellent for grafted SHF composite with higher loading. The weight loss observed was 71.36% and the weight residue was 18.12%. Void volume decreased at 30% fiber loading in the case of alkali and grafted samples.

Automated summary

Due to their easy availability, biodegradability, and low cost, natural fibres have dominated synthetic fibres in recent years. Epoxy-based composites fabricated from sunn hemp waste fibres showed excellent mechanical properties, chemical resistance, and dimensional stability.