Industrially applicable methods of poly(methyl methacrylate)/organophilic montmorillonite nanocomposites preparation: Processes and cast materials characterization

• Commercial organophilic montmorillonites as nanofillers of cast PMMA panels
• Cast PMMA panels prepared via polymerization of raw monomer and PMMA/monomer syrup.
• Organophilic montmorillonites improve mechanical and thermal properties of PMMA.
• Low content of organophilic montmorillonite in PMMA (< 0.05 wt.%) is preferred.

The poly(methyl methacrylate) (PMMA)/organophilic montmorillonite cast nanocomposites were prepared via bulk free-radical polymerization of raw monomer (MMA) and PMMA/MMA syrup. Three types of commercial organophilic montmorillonites (o-Mt) (swelled in either MMA or syrup and additionally homogenized in a high-speed flow homogenizer or twin-screw extruder, respectively) have been utilized to PMMA panels manufacturing. An influence of o-Mt type and content as well as its dispersion methodology on mechanical, thermal and optical properties has been investigated. Although PMMA panels containing o-Mt exhibited similar tensile strength (in respect to unmodified PMMA samples), higher hardness (+ 2 HBa units) and flexural strength (+ 15% for PMMA prepared using raw monomer and unhomogenized o-Mt/MMA paste) have been observed. Moreover, introduction of o-Mt into polymeric matrix resulted in increased thermal stability, Vicat softening temperature (+ 5 °C) and glass transition temperature value determined by DMTA technique (+ 5 °C for PMMA/o-Mt composites prepared from syrup with non-extruded clay mineral paste). XRD and TEM analysis showed full or partial exfoliation of organophilic montmorillonites in polymer matrix, respectively.