In this study cellulose nanofibers prepared by acid hydrolysis,
raw or silane treated, were used as reinforcement for PLA. Thermal
properties of PLA and PLA modified with cellulose nanofibers
were deeply investigated and the DSC results correlated well with
morphological features observed by advanced AFM techniques.
Crystalline grains consisting of inclined stacks of PLA lamellae
were observed by Peak Force QNM, emphasizing a beginning of
PLA crystallization. QNM images showed an improved dispersion
of cellulose nanofibers in PLA after silane treatment.
DSC measurements revealed higher degree of crystallinity for
the composites containing untreated nanofibers and demonstrated
the role of cellulose nanofibers as nucleating agents. Improved
adhesion between the silanized nanofibers and PLA could explain
the lower crystallinity content and the higher cold crystallization
temperature than for composites containing untreated fillers.