Fundamental Investigation of Biomass Interaction for Green Composites: Experiments and Molecular Dynamics Simulations

Understanding biomass interaction is critical for bottom-up design of novel biocomposites and existing manufacturing processes. In this study, interactions between bioadhesives (lignin, carbohydrates, or proteins) and fibers (cellulosic fiber or wood fiber) are elucidated via experimental bonding strength tests and molecular dynamics (MD) simulations. Experimental results reveal a good, nearly linear correlation between the composite's density and tensile strength, a finding which has rarely been reported previously. Adhesives are compared to one another: soy protein isolate is found to be the best for pinewood fiber, while apple pectin and soy protein isolate are the best for alpha-cellulose fiber. It is further shown that the fiber type plays an important role in defining the composite strength. In agreement with experiments, the MD simulations at nanoscale predict a linear strength to density correlation; this is driven by the hydrogen bond (H-bond) content in the composite. The H-bond content is also found to determine the varied performances of different adhesives.