(436f) Interfacial Adhesion and Strain Hardening in Polymer Nanocomposites

The effect of interfacial adhesion on strain hardening behavior in extensional flow has been investigated for intercalated polymer-clay nanocomposites with a small loading of nanofiller. The nanocomposites were prepared with a functionalized polypropylene (linear chains) as the matrix and organoclay at 5wt% loading with and without silane treatment. The strain hardening behavior of the nanocomposite melts was evaluated in uniaxial extensional flow at 10°C and 15°C above the melting point of 145°C and at four different strain rates with the Extensional Viscosity Fixture mounted on a TA-ARES instrument. Strain hardening of the melt was observed in both nanocomposites but to a lesser extent in the case of silane treated organoclay. The strain hardening behavior of the nanocomposite melts was described with the molecular stress function model of Wagner et al. (2001, 2006) and the maximum value of tube diameter contraction, f²_max fitting the extensional viscosity data was found for each case. Since the composites were intercalated, the interfacial adhesion between polymer matrix and nanoclay could be evaluated experimentally with the help of stress strain curves from tensile tests at 5°C and 10°C below the melting point ? cf. Piggott.

Wagner, M.H., Rubio, P. and Bastian, H., J. Rheol. 45(6), 1387 (2001)

Piggott, M.R. Ch 8 in Load Bearing Fibre Composites, Pergamon Press 1980