Polymers and Polymer Composites

MELT VISCOELASTICITY OF POLYAMIDE 6 ORGANOCLAY NANOCOMPOSITES

August 1, 2003 By: Karaman V M; Shumsky V F; Privalko E G; Privalko V P; Lehmann B; Friedrich K Research article

Title: MELT VISCOELASTICITY OF POLYAMIDE 6 ORGANOCLAY NANOCOMPOSITES
Page Range: p.663-668
Author(s): Karaman V M; Shumsky V F; Privalko E G; Privalko V P; Lehmann B; Friedrich K
File size: 70K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 11
Issue No: No. 8

Abstract
Thermoplastics reinforced with relatively small amounts of organoclay particles are particularly useful as engineering materials. However, their processability has been found to present some problems with respect to the extreme sensitivity of melt flow behaviour to the aspect ratio of clay nanoparticles and to the quality of their dispersion. In addition, viscoelastic studies of irradiation-grafted nano-inorganic particle-filled PP composites in the melt state, revealed the onset of a plastic yield phenomenon for a nanocomposite with the filler volume content as low as 4.68%. This study focuses on commercial nanocomposites of nylon-6 which were prepared by melt compounding with organoclay hybrids, and which were subsequently characterised by complex viscosities and relaxation time spectra derived from storage and shear loss modulus. Results were rationalised in terms of (P1)model considerations. At the lowest clay loading (2.5%), the Newtonian viscosity suggested a lower equilibrium elasticity modulus of an entangled melt, as if the organoclay particles had acted as specific ‘diluents’ for the initial entanglement network. At increased clay contents, this effect was taken over the growing importance of strong interactions at the nanoparticle/melt interface, leading to the formation of a fairly thick boundary interphase (BI) around the nanoparticles, and eventually, resulting in a build-up of an ‘indefinite cluster’ of clay nanoparticles coated with BI at the highest clay loading (7.5%). 17 refs.


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