From nature to application: Transformative developments in natural rubber compounding

Natural rubber (NR) is a high-performance elastomer valued for its elasticity, tensile strength, and tear resistance, making it indispensable in diverse industrial applications, including automotive tires, vibration-damping systems, medical devices, and consumer goods. However, conventional synthetic additives used in NR compounding pose environmental and health concerns due to their persistence, toxicity, and non-renewable origin. This review critically examines recent developments in natural-based additives—sourced from plants (e.g., lignin and vegetable oils), animals (e.g., collagen and chitosan), and minerals (e.g., silica and clay)—and their integration into NR compounding and processing. The discussion highlights how these bio-derived alternatives influence rheological, mechanical, thermal, and chemical properties of NR compounds, with comparative insights against conventional formulations. Challenges related to additive availability, processing behavior, cost, and suitability for high-performance applications are highlighted, alongside their potential to reduce reliance on petroleum-based materials. Finally, emerging directions such as smart/nano-enabled additives and AI/ML-driven formulation optimization are considered, underscoring the potential for natural-based additives to advance environmentally sustainable practices while meeting evolving industrial demands.