Thermally recyclable polylactic acid/cellulose nanocrystal films through reactive extrusion process

This paper reports a single step reactive extrusion process for fabrication of thermally stable, polylactic acid grafted cellulose nanocrystal(PLA-g-CNC) nanocomposite films using dicumyl peroxide as cross-linking agent. PLA-g-CNC nanocomposites were recycled without significant breakage in the molecular structure of PLA. The grafted PLA chains shields the sulfate and hydroxyl groups of CNCs, thereby enhancing the compatibilization with PLA matrix and preventing thermal degradation during extrusion. NMR and FTIR spectroscopy studies showed that amorphous PLA chains grafted on CNC surface through CeC bonds formation. Presence of such chemical crosslinks led to efficient transfer of modulus of CNCs to PLA matrix, thereby improving the tensile strength and young's modulus by similar to 40% and similar to 490%, respectively. Recycling of PLA-g-CNC doesn't alter the molecular weight, thermal, crystallization and mechanical properties of the nanocomposites significantly. Therefore, the current study provides a novel approach for fabricating CNC-reinforced-PLA nanocomposites which can be easily recycled and reused for multiple cycles. (C) 2016 Elsevier Ltd. All rights reserved.