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Novel Copolymers as Dispersants/Intercalants/Exfoliants for Polypropylene‐Clay Nanocomposites
Author(s) -
Moad Graeme,
Dean Katherine,
Edmond Lex,
Kukaleva Natalia,
Li Guoxin,
Mayadunne Roshan T A,
Pfaendner Rudolf,
Schneider Armin,
Simon George,
Wermter Hendrik
Publication year - 2006
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200690015
Subject(s) - dispersant , materials science , organoclay , nanocomposite , copolymer , polypropylene , montmorillonite , composite material , acrylate , thermal stability , ultimate tensile strength , methacrylate , butyl acrylate , comonomer , maleic anhydride , chemical engineering , dispersion (optics) , polymer chemistry , polymer , physics , optics , engineering
The use of various copolymers as dispersants/intercalants/exfoliants in polypropylene (PP)‐clay nanocomposites based on unmodified montmorillonite clays (NaMMT) has been explored. The primary objective of this research has been to find dispersants that allow PP nanocomposites to be formed by direct melt mixing, that are effective with unmodified clays and that comprise only a minor component of the overall composition both with respect to both clay and PP. Two classes of dispersants were investigated: PEO‐based nonionic surfactants and amphiphilic copolymers based on a long chain (meth)acrylate (e.g. octadecyl acrylate) and a more polar comonomer (e.g. maleic anhydride, N‐vinylpyrrolidone, methyl methacrylate). The state of dispersion achieved and the properties of the derived nanocomposites were found to depend strongly on both on the level of dispersant and its overall composition but interestingly properties are not particularly dependent on the dispersant architecture (i.e. whether statistical, gradient or block copolymer). The nanocomposites possess a tensile modulus up to 40% greater that the precursor PP while elongation at break and impact strength are significantly improved over “clay alone” composites and reference organoclay‐based nanocomposites. Also notable are significantly better thermal and thermo‐oxidative stability as compared to both PP and “clay alone” composites. For optimal properties, it is both necessary and desirable that the surfactant should only be a minor constituent (20–50 wt‐%) of the composition with respect to clay.