Valorization and techno‐economic analysis of rice straw‐derived biocomposites for sound‐insulating applications

The transformation of biorenewable feedstocks into biocomposites for sound‐insulating applications is a promising alternative to the use of fossil‐derived noise control materials. It is also an innovative strategy for waste‐to‐wealth technologies within the circular economy framework. This study examined the feasibility and techno‐economics of rice straw (RS)‐derived biocomposites for sound‐insulating applications. Bio‐based binders – Protobind‐1000 lignin (PBL) and guar gum (GG) – were used in varying concentrations to develop six biocomposites: RS 0 (100% RS), RS A (50% RS, 25% PBL, 25% GG), RS B (50% RS, 37.5% PBL, 12.5% GG), RS C (50% RS, 12.5% PBL, 37.5% GG), RS D (50% RS, 50% PBL, 0% GG), and RS E (50% RS, 0% PBL, 50% GG). These were evaluated for functional, microstructural, thermal, flammability, mechanical, biodegradability, physical, and acoustic properties. Average sound transmission loss ranged from 28 to 30 dB, and thermal conductivity ranged from 0.255 to 0.315 W m −1 K −1 (25–75 °C). Flammability tests confirmed that all samples met horizontal test criteria and achieved V‐0 to V‐2 ratings under vertical conditions. The RS B biocomposite demonstrated the highest mechanical performance, achieving a tensile strength of 13.76 MPa and a flexural strength of 1.30 MPa. Soil burial tests confirmed the biodegradability of all biocomposites, with visible surface cracking and up to 25% weight loss after 85 days. The techno‐economic analysis indicated that repurposing the existing plant for biocomposite production was more financially advantageous than building a new plant. The repurposed plant was projected to generate a net present value of $2.91 million and recoup its initial investment in 3.25 years, outperforming the new plant's estimated $1.64 million net present value and 5 year payback period.