Revalorization of barley straw and husk as precursors for cellulose nanocrystals extraction and their effect on PVA_CH nanocomposites

tPoly(vinyl alcohol) (PVA) blended with natural chitosan (CH) was selected as matrix for the production, bysolvent casting in water, of nanocomposite films containing cellulose nanocrystals (CNC) extracted frombarley residues, that were introduced in PVA CH systems as reinforcement phases. Cellulose nanocrys-tals were successfully extracted from both barley straw and husk by applying two different approaches, achemical alkaline and an enzymatic pre-treatment, followed by acidic hydrolysis. The results evidencedthe major effectiveness of the enzymatic pre-treatment on the quality of obtained CNC; nevertheless,all the different typologies of nanocrystals were added to the polymers and the morphological, optical,mechanical response, thermal and migration characteristics were investigated, whereas antimicrobialassay were carried out to evaluate the bactericidal effect induced by chitosan presence. The resultsindicated that chitosan reduced the optical transparency and the mechanical response of PVA matrix,whereas its combination with CNC (especially when extracted by enzymatic treatment and added at ahigher content) was able to modulate the optical properties, the mechanical and thermal responses. More-over, inhibitions on fungal and bacterial development were detected for PVA CH CNC ternary systems,suggesting their protective function against microorganisms contamination.