Structural analysis of polyamide/clay nanocomposites

Abstract

X-ray diffraction (XRD) methods and differential scanning calorimeter (DSC) thermal analysis have been used to investigate the structural changes of polyamide 6 (PA 6)/clay and polyamide 6,6 (PA 6,6)/clay nanocomposites. Polyamide 6/clay was prepared by the intercalation of ε-caprolactam and exfoliation of the layered hosts by subsequent polymerization. The PA 6,6/clay nanocomposites were produced by the intercalation of PA 6,6 into swellable-layered hosts. Both XRD data and DSC results indicate the presence of polymorphism in PA 6 as well as in PA 6/clay nanocomposites. This polymorphic behavior is dependent on the cooling rate of the PA 6/clay nanocomposites from the melt and on the presence of clay in the PA 6/clay nanocomposites. Quenching from the melt induces crystallization into the γ-crystalline form; and addition of clay increases the crystallization rate of the α-crystalline form. Meanwhile XRD and DSC results show only the presence of the α-crystalline form for PA 6,6/clay nanocomposites. This result is independent of the presence of clay in PA 6,6/clay nanocomposites and the cooling rate of PA 6,6/clay nanocomposites from melt. The effect of thermal annealing on the crystalline structure of PA 6/clay nanocomposites in the range between T _g and T _m is also discussed.

Keywords:

• Polyamide
• Nanocomposite
• Polymorphism
• Thermal annealing

Acknowledgments

The financial support provided by NSC through the project NSC89-2216-E-214-031 was greatly appreciated.