(327c) Selection and Processing of Food Grade Plasticizers to Compatibilize Cellulose Nanocrystals / Ethylene Vinyl Alcohol Copolymer Nanocomposites

Dispersing hydrophilic additives, such as cellulose nanocrystals (CNCs) into hydrophobic polymers is a significant challenge that limits the range of nanocomposites that can be developed with CNCs. In this study, food grade plasticizers (monolaurin and glyceryl monostearate) were investigated as additives to disperse CNCs into hydrophobic ethylene vinyl alcohol (EVOH). The compatibility of these plasticizers with CNCs and EVOH were assessed using Hansen Solubility Parameters by comparing the concluded solubility spheres for each species. This analysis revealed two main findings. First, that glyceryl monostearate is a poor compatibilizer for EVOH while monolaurin is a good compatibilizer. Secondly, that a 40/60 ethanol/water cosolvent would be the most effective choice for processing. These findings were employed to develop nanocomposite films of EVOH, CNCs, and monolaurin. Excellent dispersion of CNCs into EVOH was achieved by compounding pre-mixed hydrophobic monolaurin and hydrophilic CNCs prepared by co-dissolution/evaporation in the 40/60 ethanol/water co-solvent. Experimental analyses of the nanocomposite films reveal that inclusion of the compatibilizer allows for optimization of mechanical properties (tensile strength, Young’s modulus) and performance. In particular, we describe how the addition of CNCs and monolaurin improve the performance of these nanocomposites in humid environments. Overall, this work highlights the efficacy of employing HSPs to optimize performance of composite materials.