Cyclic olefin copolymer/layered silicate nanocomposite: solid and melt viscoelastic properties and degradation behavior

Organoclay nanocomposites based on cyclic olefin copolymer (COC) with various contents of layered silicate nanoparticles were prepared via melt blending. The influence of processing conditions and nanoclay content on solid state viscoelastic and melt rheological properties as well as thermal degradation behavior was studied. The state of dispersion was investigated using X-ray diffraction technique which showed a strong dependence on composition, where an exfoliated morphology was identified in high nanoclay loading. Besides, the processing conditions, i.e., screw rotation speed and mixing time were also found to strongly influence the state of nanophase dispersion. The rheological investigations revealed a remarkable increase in storage shear modulus and complex viscosity values upon nanoclay incorporation. Furthermore, dynamic mechanical analysis gave an evidence of increasing stiffness after nanoclay was added into COC matrix; however, no detectable change in glass transition peak was brought about. The results from thermogravimetry also exhibited a rising trend in thermal stability values as nanophase organoclay was incorporated, for which the random chain scission was suggested as the prevailing mechanism based on a theoretical analysis.