The Effects of Lignin Nanoparticle Contents on Microstructure and Properties of Polymers with Different Molecular Weights

Lignin, the second most abundant biopolymer after cellulose in most plants, has evolved from a by-product to a valuable material of growing interest in academia and industry. Recent research highlights diverse applications of lignin, focusing on enhancing material properties and functionalities through lignin nanoparticles (LNPs) in polymer nanocomposites (PNCs).

In this study, LNPs were produced via anti-solvent precipitation, utilizing lignin's amphiphilic nature and the LNP PNC were produced employing polyvinyl alcohol (PVA), a biodegradable polymer as a matrix polymer. We examined how LNPs influence on the microstructure, dynamics and physical properties of PNC with varying LNP content and the molecular weight of PVA. The PNC microstructure was investigated using Small-Angle X-ray Scattering (SAXS) and the its rheological properties were examined to reveal LNP dispersion within the polymer matrix and polymer chains dynamics. We found that the structural differences in dispersion from the solution state influenced the crystallinity and thermal properties of PNCs.

Our study aims to elucidate the role of LNPs and the mechanisms behind polymer property enhancement at the microstructural level, contributing to the growing knowledge of lignin-based nanocomposites and their potential applications in sustainable materials science.