Sustainable Biocomposites from Oyster Shell and Bamboo Charcoal Reinforced Polybutylene Succinate (PBS) for Agricultural Applications

Large quantities of oyster shells and bamboo waste contribute to environmental pollution, highlighting the need for sustainable valorization strategies. In this study, green biocomposites based on polybutylene succinate (PBS) reinforced with thermally treated shell waste (TSW) at loadings of 0–15 wt% (in increments of 5 wt%) and bamboo charcoal (BC) at a fixed content of 3 wt% were developed. To the best of the authors’ knowledge, no previous studies have reported on hybrid PBS composites incorporating both TSW and BC fillers. The mechanical properties and fracture surface morphology of neat PBS and the developed biocomposites were investigated. The results showed that the addition of BC maintained the impact resistance while significantly improving the tensile and flexural properties, stiffness, and hardness. Although the addition of TSW enhanced stiffness, rigidity, and tensile and flexural moduli, it reduced the impact resistance and flexural strength. Overall, the impact strength, tensile strength, flexural strength, and elongation at break tended to decrease with increasing TSW content, whereas the tensile and flexural moduli increased. Overall, the PBS–BC sample was identified as the most suitable material for nursery plant pots and mulch film due to its high impact and flexural strengths, along with a relatively moderate flexural modulus among the PBS composites. The hybrid PBS–BC–TSW05 biocomposite (5 wt% TSW and 3 wt% BC) was identified as the optimal hybrid formulation because of its balanced mechanical performance.