Abstract :
In this study, mechanical properties such as tensile, flexural and impact strengths of
hemp/phenol formaldehyde (PF), basalt/PF and hemp/basalt hybrid PF composites have
been investigated as a function of fibre loading. Hemp fibre reinforced PF composites and
basalt fibre reinforced composites were fabricated with varying fibre loading i.e. 20, 32, 40,
48, 56 and 63 vol%. The hybrid effect of hemp fibre and basalt fibre on the tensile, flexural
and impact strengths was also investigated for various ratio of hemp/basalt fibre loading
such as 1:0, 0.95:0.05, 0.82:0.18, 0.68:0.32, 0.52:0.48, 0.35:0.65, 0.18:0.82 and 0:1. Total fibre
loading of the hybrid composites was 40 vol%. The results showed that the tensile strength
and elongation at break increase with increasing fibre loading up to 40 vol% and decrease
above this value for hemp fibre reinforced PF composite. Similar trend was observed for
flexural strength and the maximum value was obtained for 48 vol% hemp fibre loading.
Impact strength of hemp/PF composite showed a regular trend of increase with increasing
fibre loading up to 63 vol%. Tensile strength, flexural strength and impact strength values
of basalt/PF composites were found to be lower compared to hemp/PF composites. The
tensile strength and elongation at break of basalt/PF composite increased by incorparation
of basalt fibre up to 32 vol% and decreased beyond this value. Flexural strength of
basalt/PF composite decreased linearly with fibre loading. However, the maximum impact
strength was obtained for 48 vol% basalt fibre loading. For hemp/basalt hybrid PF
composite, the tensile strength decreased with increasing basalt fibre loading. On the other
hand, the flexural and impact strengths showed large scatter. The maximum flexural
strength value was obtained for 0.52:0.48 hemp/basalt ratio. Corresponding value for
impact strength was obtained for 0.68:0.32 hemp/basalt fibre ratio.
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