Investigation of the Effects of Hybrid Agro Waste-Fillers on the Properties of Flexible Polyurethane Foams for Nursery Farming Applications

The use of agro-waste materials as fillers in polymer composites offers a sustainable route to reducing environmental impact and production cost while enhancing material performance. This study investigates the influence of guinea corn husk/snail shell hybrid filler on the physical, mechanical, morphological, and biodegradability properties of flexible polyurethane foam intended for nursery farming applications. The hybrid filler, composed of equal proportions of lignocellulosic guinea corn husk and calcium-carbonate-rich snail shell, was incorporated at 0–25 wt%. Results showed that increasing filler loading prolonged foaming reactions and increased density, with rise time increasing from 145 s to 166 s, cure time from 7.5 to 8.8 min, and apparent density from 28.4 to 32.2 kg/m³. Mechanical performance improved progressively, as tensile strength, flexural strength, compressive strength, and hardness increased with filler content, while strain at break decreased, indicating enhanced stiffness but reduced ductility. Scanning electron microscopy revealed a transformation from large, irregular cells in the control foam to smaller, more uniform cells with thicker walls in filled samples. Soil burial testing confirmed the biodegradable nature of the composite material. Overall, the guinea corn husk/snail shell hybrid filler significantly improved structural integrity and load-bearing capacity while maintaining environmental compatibility, demonstrating strong potential for cushioning, root protection, and seedling support in nursery farming systems.