Mechanistic Insight into Lignin as a Green Rubber Additive: Correlation Analysis of Structural Parameters

Lignin, as a renewable and sustainable additive to replace traditional rubber additives, holds great potential in the development of green tires. However, its application is limited by its complex and heterogeneous structure and its poor compatibility with rubber. This study focuses on the complex structure of lignin, using the Pearson correlation coefficient (PCC) and Spearman correlation coefficient (SCC) to deeply analyze the intrinsic relationship between its structural features and rubber performance. The experimental results demonstrate that the incorporation of lignin significantly enhances the plasticity of rubber materials. Meanwhile, PCC and SCC reveal a significant correlation between the hydroxyl group density in lignin and the performance of rubber. Specifically, an increase in hydroxyl group density contributes to the enhancement of rubber plasticity while concurrently leading to a reduction in its strength. This finding provides important theoretical guidance for the molecular design of lignin-based rubber additives while also confirming the feasibility of lignin as a green rubber additive. Additionally, it offers a new perspective for using data analysis methods to investigate the influence of lignin structure on material properties.