Ball-milling Promoted Chemical Bonding between Cellulose and Plastics
Cellulose has attracted growing interest as the most promising material to take the place of synthetic polymers to a considerable extent in the twenty-first century, because of its massive reproducibility and environmental benefits. However, native cellulose exhibits not only insolubility in the usual solvents but also no thermoplasticity, due to the tight packing of cellulose chains through intra- and intermolecular hydrogen bonding formed all over them. Ball milling of fibers of native cellulose in the solid state produces fine powders of amorphous cellulose with parallel chains. The amorphous powders exhibit unique properties, particularly emphasized by a transformation into cellulose II on addition of a specific amount of water. The amorphous powders are so reactive that they can effectively form ester bonds with maleic anhydride-grafted polyethylene or polypropylene. Consequently, resultant cellulosic composites possess improved toughness and ductility due to the formation of an interphase between the homogeneously distributed particles of cellulose and the polymer matrix. Therefore, the activation of native cellulose by ball milling will be an important base for its extensive applications.