Preparation and characterization of the nanocomposites from chemically modified nanocellulose and poly(lactic acid)

Cellulose nanocrystals (CNCs) are renewable and sustainable filler for polymeric nanocomposites. However, their high hydrophilicity limits their use with hydrophobic polymer for composite materials. In this study, freeze-dried CNCs were modified by transesterification with canola oil fatty acid methyl ester to reduce the hydrophilicity. The transesterified CNCs (CNCFE) were compounded with PLA into nanocomposites. CNCFE with long-chain hydrocarbons plays a role as plasticizer. Increasing CNCFE loadings resulted in clear plasticizing effects. Lower Tg and Tm were achieved for CNCFE-based nanocomposites. Plasticizing nanocomposite melt with CNCFE can mitigate the degradation of CNCs during thermal processing. The elongation at break of nanocomposites containing 5% CNCFE was increased. Dynamic rheological study showed the highest elastic and viscous moduli (G′ and G″) and complex viscosity (G*) of nanocomposites with addition of 2% CNCFE. By tailoring the loadings of the transesterified CNCs, tunable structure and properties of nanocomposites can be obtained.