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X-ray diffraction methods and DSC thermal analysis have been used to investigate the structural change of nylon 6/clay nanocomposites. Nylon 6/clay has prepared by the intercalation of ζ-caprolactam and then exfoliaton of the layered saponite or montmorillonite by subsequent polymerization. Both X-ray diffraction data and DSC results indicate the presence of polymorphism in nylon 6 and in nylon 6/clay nanocomposites. This polymorphic behavior is dependent on the cooling rate of nylon 6/clay nanocomposites from melt and the content of saponite or montmorillonite in nylon 6/clay nanocomposites. The quenching from the melt induces the crystallization into the γ crystalline form. The addition of clay increases the crystallization rate of the α crystalline form at lower saponite content and promotes the heterophase nucleation of γ crystalline form at higher saponite or montmorillonite content. The effect of thermal treatment on the crystalline structure of nylon 6/clay nanocomposites in t he range between Tg and Tm is also discussed., INTRODUCTION Polymer nanocomposites, defined by the particle size of the dispersed phase containing at least one dimension in the range of 1~100 nm, have received increasing interest because of their [...]

The fluorescence quantum efficiency and the internal conversion quantum yield of 0.59 plusmn 0.02, and the intersystem crossing quantum yield of 0.11 plusmn 0.01 are presented. The fluorescence lifetime of ca. 490 ps is measured to estimate the relative lifetime of 1.64 ns for the singlet excitons and nonradiative decay rate constants, for the internal conversion and intersystem crossing.