Modification of hemp fibers through alkaline attack assisted by mechanical milling: effect of processing time on the morphology of the system

This paper reports the possibility of functionalizing hemp fibers (HF) through a mechano-chemical treatment assisted by an easily scalable top-down technology. The mechanical action was able to remove non-cellulosic material and to cause exposure of the cellulose microfibrils. Its influence on structure, morphology, and properties of hemp fibers has been analyzed by means of the scanning electron microscopy, X-Ray, FTIR and Raman spectroscopy. The milling process induced a change in crystalline content of hemp fibers, which decreased after a treatment time of 30 min. The crystallinity index and cellulose chain arrangement influence the thermal stability of hemp fibers. In order to compare the improved properties of mechanochemically treated HF respect to the HF modified with conventional alkalization, they were introduced, as green reinforcement, into a pectin matrix. Thermal and mechanical properties demonstrated the effectiveness of milling treatment in improving the considered physical properties of the pectin matrix.