Preparation of polymeric nanocomposites and their structure-property relationships

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TKK dissertations, 165
Polymer nanocomposites were prepared by two different methods: (1) by melt blending polypropylene and layered clay in the presence of compatibilizers, and (2) by electrospinning poly(vinyl alcohol)/nanoclay, poly(vinyl alcohol)/nano titanium dioxide, and polyamide/nanoclay dispersions. In this work, the preparation of PP/nanoclay composites began by exchanging the originals of natural layered clay for octadecylamine and N-methylundecenylamine. This modification yielded the desired intercalated clay structure. The ability of well-controlled stereospecific hydroxyl-functionalized polypropylene (PP-co-OH) compatibilizer to enable the PP-matrix to penetrate between the modified clay sheets and the properties of the resulting polymer/nanocomposite were studied. Also, a non-polar PP-based wax was tested as a compatibilizer in the composites, but the desired clay nanostructure was not achieved. The PP-co-OH was shown to be almost as effective a compatibilizer as the well-known maleinic anhydride-grafted polypropylene. Furthermore, addition of fire retardant particles to the melt blend improved the degree of clay exfoliation, presumably due to increased shear stress and grinding. The nanocomposites showed improved stiffness and reduced heat release rates with weakened toughness and increased moisture absorption relative to the unfilled PP or PP/clay composites. This work also consisted of electrospinning of functional-poly(vinyl alcohol) and polyamide-6,6 with nanoclays and coated nanoscale titanium dioxide particles. The dispersions that were electrospun were prepared by two methods: by mixing the components together in a suitable solvent and by an in situ polymerization in the presence of nanoparticles. We were able to produce visible fiber coating depositions on substrates with uniform filler distributions along the fibers or drops. The dispersions prepared by polymerization resulted in more evenly distributed fillers along the electrospun fibers than the dispersion prepared by mixed the components together.
polymer/nanocomposites, nanoclay, functional polyolefin, electrospinning
Other note
  • [Publication 1]: Noora Ristolainen, Ulla Vainio, Santeri Paavola, Mika Torkkeli, Ritva Serimaa, and Jukka Seppälä. 2005. Polypropylene/organoclay nanocomposites compatibilized with hydroxyl-functional polypropylenes. Journal of Polymer Science Part B: Polymer Physics, volume 43, number 14, pages 1892-1903.
  • [Publication 2]: Noora Ristolainen, Ulla Hippi, Jukka Seppälä, Antti Nykänen, and Janne Ruokolainen. 2005. Properties of polypropylene/aluminum trihydroxide composites containing nanosized organoclay. Polymer Engineering and Science, volume 45, number 12, pages 1568-1575.
  • [Publication 3]: Noora Ristolainen, Pirjo Heikkilä, Ali Harlin, and Jukka Seppälä. 2006. Poly(vinyl alcohol) and polyamide-66 nanocomposites prepared by electrospinning. Macromolecular Materials and Engineering, volume 291, number 2, pages 114-122.
  • [Publication 4]: Ulla Hippi, Noora Ristolainen, Barbro Löfgren, and Jukka Seppälä. 2008. Metallocene catalyzed functionalized polyolefins in composites. In: Domasius Nwabunma and Thein Kyu (editors). Polyolefin Composites. John Wiley & Sons. Chapter 8, pages 207-227.
  • [Publication 5]: Noora Ristolainen, Pirjo Heikkilä, Ali Harlin, and Jukka Seppälä. 2008. Electrospun nanofibers prepared by two methods: in situ emulsion polymerized PVA/nanoTiO2 and mixing of functional-PVA with nanoTiO2. AUTEX Research Journal, volume 8, number 2, pages 35-40.