Mechanical behavior and microstructural analysis of rotomolded LLDPE composites filled with surface-modified peanut shell powder

This research explores the synthesis of sustainable polymer composites through the incorporation of alkali-treated peanut shell powder (TPSP) in linear low-density polyethylene (LLDPE) using rotational molding. The peanut shells were treated with 5% NaOH solution, and FTIR analysis followed by thermogravimetric analysis proved the elimination of non-cellulosic content such as lignin and hemicellulose. Composites of TPSP concentration in the range of 3-15 wt% were analyzed for mechanical and morphological properties. Tensile strength fell from 13.82 MPa to 7.51 MPa with increasing TPSP concentration, whereas stiffness increased substantially. The tensile modulus rose by 93% (395.06 MPa) at 9 wt%, and impact strength rose by 94% (107.22 J/m) up to 9 wt%, before reducing at higher concentrations. Flexural modulus reached its peak at 9 wt% (482.71 MPa), with an increase of 42%, and maintained a 21% increase at maximum loading. Microstructural analysis proved excellent fiber dispersion and matrix adhesion in the range of 3-9 wt%, with agglomeration at higher concentration. The research concludes that 9 wt% TPSP achieves an optimal balance of mechanical properties and processability as a sustainable reinforcement for LLDPE composites in applications demanding high stiffness and impact resistance. This research identifies TPSP as cost-effective, eco-friendly filler for rotational molding.