A Combined Theoretical and Experimental Study of the Polymer Matrix-Mediated Stress Transfer in a Cellulose Nanocomposite
Anna Peterson, Aleksandar Y. Mehandzhiyski, Leo Svenningsson, Agnieszka Ziółkowska, Roland Kádár, Anja Lund, Linda Sandblad, Lars Evenäs, Giada Lo Re, Igor Zozoulenko, Christian Müller
Abstract
We study composites of cellulose nanocrystals (CNCs) in an ionomer matrix of poly(ethylene-stat-sodium acrylate) and find that direct cellulose/cellulose interactions in the composite are not a requirement for achieving reinforcement.While isotropic composites only show a slightly enhanced stiffness compared to the neat ionomer, a more substantial increase in Young's modulus by a factor of up to 5 is achieved by uniaxial alignment of the composites through melt spinning.The orientation of CNC in melt-spun composites reduces the probability of cellulose/ cellulose interactions, which suggests that cellulose/polymer interactions must be present that lead to the observed reinforcement.Molecular dynamics simulations confirm strong cellulose/polymer interactions in the form of ionic interactions as well as hydrogen bonding.These cellulose/polymer interactions facilitate efficient stress transfer, leading to the high reinforcing effect of CNC, while cellulose/cellulose interactions play a minor role in the mechanical response of the composite.