Sustainable LDPE composites reinforced with Syzygium cumini seed biofillers: Mechanical, thermal, and morphological performance assessment

Environmentally sustainable polymer composites utilizing agro-waste biofillers provide a responsible method for improving thermoplastic performance. This work involved the fabrication of low-density polyethylene composites supplemented with Syzygium cumini seed biofillers using injection molding, utilizing filler loadings of 0, 10, 20, 30, and 40 wt%. The mechanical, physical, thermal, and morphological qualities were extensively assessed. The findings indicated that mechanical performance enhanced with rising filler content, peaking at 20 wt% Syzygium cumini, where the composite had a tensile strength of 6.58 MPa, an elastic modulus of 31.4 MPa, and a Shore D hardness of 42. The density grew significantly with the addition of filler, showing the successful assimilation of the biofiller. Dynamic mechanical investigation indicated superior stiffness retention at 20 wt% Syzygium cumini, whereas 10 wt% Syzygium cumini exhibited higher damping characteristics. Fourier-transform infrared spectroscopy and Energy-dispersive X-ray spectroscopy investigations validated the existence of lignocellulosic functional groups and bio-derived elemental composition, whereas scanning electron microscopy observations revealed homogeneous filler dispersion at optimal loading levels. Syzygium cumini seed particles are an economical and sustainable reinforcing filler for low-density polyethylene, with 20 wt% determined as the ideal reinforcement concentration. • Sustainable LDPE composites were developed using Syzygium cumini seed agro-waste biofillers. • Injection moulding enabled uniform dispersion and scalable composite fabrication. • Optimum 20 wt% filler achieved maximum tensile strength and hardness. • DMA revealed tunable stiffness and damping behaviour with filler loading. • SC seed biofillers offer a cost-effective route for sustainable polymer composites.