Characteristics of polypropylene biocomposites: effect of chemical treatment to produce cellulose microfiber

Abstract In this study, cellulose microfibers were prepared by sulfuric acid hydrolysis, glyoxal crosslinking and acetylation followed by air classifying mill, and their properties including chemical structure, particle size, appearance and crystallinity were investigated. The effect of cellulose microfibers properties on characteristics of polypropylene (PP) biocomposite, such as physical, thermal and mechanical properties, was also examined. The glyoxal crosslinking enhanced the brittleness of pulp fiber, resulting in smallest particle size of microfiber and thus less entanglement in the polymer matrix. When cellulose microfibers were incorporated into PP, the crystallinity of biocomposite decreased, irrespective of microfiber type due to interference crystallization during crystal growth. Additionally, glyoxal crosslinked cellulose microfiber decreased the crystallization temperature of biocomposite, which is different from the other types of cellulose microfiber. The good dispersibility and brittleness of glyoxal crosslinked microfiber contributed to enhanced mechanical properties of biocomposite compared to the other microfiber added biocomposites.