Characterisation of Nanocellulose from Waste Pisum Sativum Sheath and its Sunn Hemp Fibre-Polyester Composite: A Step Towards Valorisation of Biomass

Demand over fossil fuel are kept raising in recent decades due to the utilization of heavy material on various industrial, transportation application. To reduce such over-dependence and produce less pollution creating substance, the light weight composite material is utilized in recent decades. The present study also investigates the mechanical, fatigue, drop load impact, and dynamic mechanical properties (DMA) of a polyester composite reinforced with silane-modified Sunn hemp fiber and nanocellulose extracted from Pisum sativum sheath biomass. The composite was fabricated using a hand layup method, with polyester resin serving as the matrix and Methyl ethyl ketone peroxide (MEKP) as the catalyst. The nanocellulose was prepared through a process of delignification and bleaching, while both the fiber and nanocellulose underwent silane treatment to enhance their compatibility with the resin. Among the specimens tested, PSC3 (2 vol% silane-treated nanocellulose) demonstrated superior mechanical properties, with a tensile strength of 141 MPa, flexural strength of 163 MPa, hardness of 84 Shore-D, and Izod impact strength of 6.6 J. In fatigue testing, PSC3 showed excellent performance, maintaining a maximum stress of 50 MPa at 103 cycles and 24 MPa at 105 cycles. The drop load impact test further confirmed PSC3's high impact resistance, with energy absorption peaking at 18 J and dissipating over 22 ms. Dynamic Mechanical Analysis (DMA) revealed that PSC3 had the highest storage modulus of 6.4 GPa at 91 degrees C and the lowest loss factor of 0.61 at 110 degrees C, indicating optimal stiffness, thermal stability, and damping behavior. The silane treatment significantly improved the fiber-matrix and filler-matrix bonding, resulting in enhanced load transfer, increased stiffness, and better overall mechanical performance. SEM analysis corroborated these findings, showing uniform dispersion of filler particles in PSC3, which contributed to its superior properties by preventing stress concentration and ensuring effective reinforcement. This study highlights the potential of silane-treated bio-based composites for applications requiring high mechanical and thermal performance such as interior body cover parts in automobile engineering, outer cover parts in power sector such turbine blade, windmill industry, and defence armour applications, sports equipment, etc.