Characterization of Pearl Millet Husk Biosilica and Areca Microfibre toughened polyvinyl alcohol flexible food packaging composite

Abstract

This study focuses on enhancing the mechanical characteristics and sustainability of flexible food packaging composites made from Polyvinyl Alcohol (PVA) reinforced with Pearl Millet Husk Biosilica and Areca Microfiber. The high silica content in biosilica from pearl millet husk provides excellent reinforcement, while areca microfiber improves the toughness and flexibility of the composite. Together, these natural fillers result in a stronger, more resilient, and environmentally friendly composite suitable for sustainable food packaging applications. The materials were processed by extracting biosilica from pearl millet husk through high-temperature calcination and chemical treatments, and areca microfiber was obtained through retting and drying of areca fruit husk. The composites were then fabricated using a solvent casting method. Mechanical testing revealed that specimen PAV1, with 1 vol% biosilica and 40 vol% areca microfiber, exhibited the best mechanical properties, including a tensile strength of 57 MPa, tensile modulus of 2.2 GPa, tear strength of 36 N/mm, and hardness of 37 Shore D, due to balanced filler dispersion, which enhances load transfer. Specimen PAV3, containing 4 vol% biosilica, showed superior performance in wear resistance with a wear rate of 0.005 mm³/Nm and COF of 0.23, dielectric properties with a permittivity of 4.95 and dielectric loss of 0.825, hydrophobicity with a contact angle of 91°, and thermal conductivity of 0.46 W/mK. These enhancements result from higher filler content that improves hardness, polarization, surface energy, and thermal pathways. SEM analysis confirmed the uniform distribution of fillers in PAV1, enhancing mechanical properties, while some agglomeration in PAV3, although creating stress points, contributed to enhanced wear and thermal properties. Overall, these composites offer a viable alternative for eco-friendly food packaging with improved mechanical, dielectric, and thermal properties.