title: Network formation of nanofibrillated cellulose in solution blended poly(methyl methacrylate) composites.
abstract: Composites of poly(methyl methacrylate) (PMMA) and nanofibrillated cellulose (NFC) were prepared by solution blending and further processed by injection and compression molding. To improve adhesion at the PMMA/NFC interface, the nanofibrils were covalently grafted with PMMA. Formation of a percolating nanofibril network was observed between 1 and 5 wt.% of NFC by dynamic rotational rheometry in molten state. This observation was further supported by the behavior of glass transition temperature which decreased at low NFC concentrations but recovered above the percolation threshold, indicating a decreased mobility of the matrix polymer. This effect was more pronounced with ungrafted NFC, possibly due to a stronger network. The unmodified NFC induced a minor degradation of the molar mass of PMMA. As thin plates, the composites were transparent at low NFC concentrations but became partially aggregated at the highest NFC concentrations. Despite the continuous NFC network, tensile testing showed no improvement of the mechanical properties.
authors.affiliation: Polymer Technology, Department of Biotechnology and Chemical Technology, Aalto University School of Chemical Technology, P.O. Box 16100, 00076 Aalto, Finland.
authors.forename: Kuisma
authors.initials: K
authors.lastname: Littunen
authors.forename: Ulla
authors.initials: U
authors.lastname: Hippi
authors.forename: Tapio
authors.initials: T
authors.lastname: Saarinen
authors.forename: Jukka
authors.initials: J
authors.lastname: Seppälä
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D055595:Mechanical Phenomena; D008970:Molecular Weight; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D055620:Optical Phenomena; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D012996:Solutions; D013696:Temperature; D014783:Viscosity
chemical_list: D012996:Solutions; D002482:Cellulose; D019904:Polymethyl Methacrylate