Cellulose nanocrystals (CNCs) are high-strength sustainable nanomaterials, the
incorporation of which to a host polymer matrix can potentially lead to
nanocomposites with superior mechanical properties. However, the mismatch in
surface energy of CNCs and common structural polymers is a challenge that needs
to be overcome to prevent the aggregation of CNCs and ensure the robust
integration of CNCs into a polymer matrix. Herein, we report an approach
involving the functionalization of CNCs with maleated-anhydride polypropylene
(MAPP) through diethylenetriamine (DETA) linkers to significantly enhance the
compatibility between CNCs and polypropylene. Polypropylene/modified CNC
nanocomposites displayed 74% and 76% increase in elastic modulus in comparison
to neat polypropylene and polypropylene/untreated CNC nanocomposites,
respectively. The tensile strength was also higher for nanocomposites with
modified CNC than neat polypropylene, as well as nanocomposites with untreated
CNCs. The tensile strength at 5.5% strain of polypropylene/modified CNC
nanocomposites was 32% and 28% larger that of polypropylene and
polypropylene/untreated CNC nanocomposites, respectively. Finally, such
CNC-based nanocomposites have a lower density than many competitive systems
resulting in opportunities to propagate this environmentally-responsible
technology to nanocomposites used in additive manufacturing, automotive
applications, construction materials and consumer products.