  This paper is an attempt to predict the thickness and modulus at the
nanometric interphase region with the knowledge on the macroscopic Young's
modulus in the polymer-clay nanocomposites. First, a systematic design of 20160
linear elastic finite element simulations are used to derive an analytical
equation between the interphase thickness, the interphase modulus, the nanoclay
content and the macroscopic Young's modulus of the nanocomposite. Four
calibration parameters in this equation are calculated based on the reported
data about NYLON6-MMT nanocomposite. Next, an analytical nanoscale equation is
developed to satisfy the necessary boundary conditions at the nanometric
interphase. Finally, the interphase thickness and modulus are calculated by the
intersection between the two equations. The validity of predictions are
examined using two distant data sets in literature. The predicted interphase
thicknesses are consistent with the experimental reports which situate around
2-8 nm in this nanocomposite. The presented approach can be used in design and
prediction of mechanical properties in wide range of isotropic triple-phasic
systems with structural features similar to polymer clay nanocomposites.
