Molecular modeling of cellulose in amorphous state part II: effects of rigid and flexible crosslinks on cellulose

Abstract

It is essential to understand the molecular level response of crosslinked cellulose chain segments upon deformation, in order to develop new agents which convey high durable-press (DP) rating to cellulose fibers with minimal strength loss. In this work models of amorphous cellulose crosslinked with both rigid and flexible crosslinks were constructed computationally for this purpose. Rigid crosslinks bound cellulose molecular segments together and blocked the chain slippage, providing cellulose models with a higher initial modulus and better elastic response. However, the loss of the chain slippage led to stress being distributed unevenly among cellulose chains. Chains in some regions were subjected higher stress and these regions were opened up much more than the rest of the cellulose, which presumably caused models to fail. When conformationally flexible crosslinks were used, breaking strain of cellulose was not significantly reduced but deformation recovery was not improved either, in comparison with the models of untreated cellulose. Conformational transitions were observed in the flexible crosslinks during extension. These results help to explain how and why rigid crosslinks work to provide wrinkle resistant properties and why they also lower tensile strength, and that just using a conformationally flexible crosslinking will not provide any recovery.