Effect of compound organification of montmorillonite on the structure and properties of polypropylene/montmorillonite nanocomposites

Abstract

demon stration of polyamide 6/MMT nanocomposites by Toyota Group [1,2]. At present, polymer/MMT nanocomposites are prepared mainly via three methods: sol-gel processing [3,4], in-situ polymerization [5,6] and melting intercalation [7−11]. The melting intercalation is commonly used to prepare the MMT nanocomposites of polyolefin such as polypropylene (PP). However, this method tends to leave a structural limitation to the prepared nanocomposites such as narrower interlayer space and worse dispersion of silicates because the interfacial interaction between the hydrophobic PP and the hydrophilic MMT are too weak to promote the intercalation of PP chains into the interlayers. It had also been reported that the polypropylene/montmorillonite (PP/MMT) nanocomposites are still thermally unstable even if MMT is organified [4]. The PP chains intercalated into the interlayers of MMT tend to be excluded out of the interlayers, resulting in lower properties of PP/MMT nanocomposites. It is important to enhance the interaction between MMT and PP by compatibilizers [12,13] or by introducing initiators or reactive groups [14,15] into the clay interlayers to form a stable intercalated structure. Graft copolymers are one of the excellent compatibilizers for polymer/clay nanocomposites. The major methods to synthesize polyolefin graft copolymers are the melting graft copolymerization [16−18], solution graft copolymerization [19,20], radiation graft copolymerization [21−23], solid phase graft copolymerization and so on. Compared to the other graft methods, solid phase graft copolymerization is a relatively new method that has the advantages of lower reaction temperature, fewer side reactions, less solvent pollution and simpler post-processing. Monomers used for solid phase graft copolymerization include maleic anhydride (MAH), styrene (St), methyl methacrylate (MMA), and butyl acrylate (BA), etc. The conventional monomer is MAH since it is strongly polar and easily available, but it has the disadvantages of difficult homopolymerization, low graft efficiency, easy sublimation and environmental pollution. Recently, some researchers had developed multi-monomer solid phase graft Abstract In this paper, reactive organic montmorillonite (RMMT), prepared with compound alkylammoniums, were used in ternary-monomer solid phase graft copolymerization in order to enhance the melting intercalation of montmorillonite (MMT), stabilize the intercalated structure, and prepare the exfoliated polypropylene/montmorillonite (PP/MMT) nanocomposites (PPMN). The structure and properties of PPMN were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), etc. Results show that the compound organification, solid phase graft copolymerization really favored the melting intercalation. The compound organification and exothermic process of the solid phase copolymerization promoted the melting intercalation. The mechanical properties, melt flow rate and Vicat softening point of PPMN significantly ...

Polypropylene nanocomposites produced by in situ grafting of n‐butyl acrylate

“…The chosen functionalizing agent is n ‐butyl acrylate (BA). To our knowledge, the BA has not been previously used to functionalize PP in the preparation of nanocomposites, not even to use the BA‐grafted PP as compabilizer, although a few authors have consider the grafting of BA onto powdered PP and even fewer have analyzed the grafting in solution . The BA, which is easier to handle than MA and is less corrosive, may promote compatibility of the polymer with the clay and the clay modifier.…”