Biodegradable nanocomposites were obtained from polylactic acid (PLA) and cellulose nanofibers with
diameters ranging from 11 nm to 44 nm. The influence of treated (with 3-aminopropyltriethoxysilane)
and untreated nanofibers on the thermal properties of PLA was investigated in detail using multiple
session Differential Scanning Calorimetry (DSC) analysis. The nucleating effect of the cellulose nanofibers
was confirmed by all the DSC runs (two melting and two crystallization steps). The morphology of both
neat PLA and nanocomposites was explored for the first time using a new powerful AFM technique,
Peak Force QNM (Quantitative Mechanical Property Mapping at the Nanoscale), which emphasized the
nanolevel characteristics by elastic modulus mapping. QNM analyses showed a better dispersion of the
silane treated nanofibers in the matrix as compared to the untreated ones. Moreover, a higher degree
of crystallinity was detected in the PLA composites containing untreated nanofibers compared to the
composites with treated ones.