(570k) Dynamics of Cellulose & Lignin during Solution Blending

The development of sustainable bioplastics has received significant attention in recent years. Ionic liquids have been employed to dissolve and blend cellulose, lignin, chitin, and other biopolymers for bioplastics development. Cellulose are the most abundant biopolymers in nature, while lignin is nature’s reserve of aromatic compounds. The molecular dynamics of the dissolution and regeneration of biopolymers have been extensively reported in literature. Here, we report experimental evaluation of the blending of cellulose and lignin solution in mixtures of ionic liquids and organic solvents and the first of its kind molecular dynamics of the blending of cellulose and lignin in ionic liquid-cosolvent mixture. From the rheology experiments, the viscosities, and effects of temperature on viscosity were used to determine interactions and thermodynamic parameters of the blending while evaluating the effects of the amount, source and processing of lignin, use of co-solvent, solid loading, and IL alkyl chain length. The homogeneity of blends were determined with NMR and microscopic observation. Lignin’s molecular weight, monomer and linkage distribution were determined with GPC, NMR and FTIR. Using experiment-based molecular structures data and appropriate force fields, molecular dynamics was implemented to compute viscosity and interactions of the cellulose and lignin structures in the blend. The results show the regions of Newtonian and shear thinning behavior of the fluid, how to avoid agglomeration and mechanical failure in bioplastics. The experiments and simulation provides valuable insights that are essential for the handling of the biopolymers and how to ensure consistent production of high quality bioplastics.