Poly(ε-caprolactone)−Clay Nanocomposites:  Structure and Mechanical Properties

The modulus−volume fraction relationship for a poly(ε-caprolactone)−montmorillonite nanocomposite follows composite materials theory provided the clay volume fraction is correctly calculated. Thus, for interpretation of mechanical properties, nanocomposites do not have to be treated as a separate class of material. The tensile modulus of biodegradable poly(ε-caprolactone) was increased by 50% at 8 wt % clay addition (as corrected for surfactant), but the more dramatic improvement was in tensile elongation at break which increased from 165% to 550% for additions of up to 10 wt % clay. Poly(ε-caprolactone) nanocomposites with various clay volume fractions were produced with two organo-modified montmorillonites. Untreated montmorillonite was used as an experimental control to compare the properties with a conventional composite over the same clay volume fraction range, The composites were confirmed and characterized by XRD, DSC, NMR, and TEM.