Effect of Gas-Grafting Pretreatment of Cellulose on Properties of Cellulose-Polypropylene Composites

This study investigated a new gas grafting method using palmitoyl chloride to enhance the hydrophobicity of cellulose fiber sheets and their blending compatibility with polypropylene.In addition, cellulose fiber sheets were produced by substituting ethanol for water in the fiber stock during sheet molding to prevent macrofibril matting on the fiber surface, thereby improving the hydrophobization efficiency achieved by gas grafting.Results revealed that alcohol-molded sheets exhibited more than twice the amount of reacted palmitoyl chloride compared to conventional water-based fiber sheets after gas grafting.Composite films made from pretreated fibers exhibited higher tensile strength than those made from un-grafted fibers.The addition of maleic anhydride polypropylene reduced fiber agglomeration and ultimately improved dispersion by decreasing the melt flow index (MFI) of the composites.However, the use of hydrophobized fibers in polypropylene composites-via gas grafting of the fiber sheets-increased the MFI due to enhanced fiber dispersibility.