Lignin-coated cellulose nanocrystals as promising nucleating agent for poly(lactic acid)

Abstract

We report the effect of lignin-coated cellulose nanocrystals (L-CNCs) on the crystallization behavior of poly(lactic acid) (PLA). PLA/L-CNC nanocomposites were prepared by melt mixing, and the crystallization behavior of PLA was investigated using differential scanning calorimetry. Isothermal crystallization data were analyzed using Avrami and Lauritzen–Hoffman secondary nucleation theory, while the equilibrium melting temperature was determined using the nonlinear Hoffman–Weeks method. The lignin-coated cellulose nanocrystals acted as a nucleating agent and significantly increased the rate of crystallization and degree of crystallinity of PLA in PLA/L-CNC nanocomposites. The Avrami exponent, n, increased in the presence of L-CNCs, displaying a conversion from lamellar morphology to two-dimensional crystal growth. PLA/L-CNC nanocomposites also gave lower values of the nucleation parameters, $$K_{\text{g}}$$ and σ e, due to a reduction in the activation energy for nucleation.