Effect of aggregation structure on fatigue characteristics of (Nylon 6/clay) composites

(Nylon 6/clay)hybrid (NCH) [(Nylon 6/montmorillonite)composite] with montmorillonite of 2wt% was prepared. Transmission electron microscopic (TEM) observation of NCH revealed that the silicate layers of montmorillonite were molecularly dispersed in NCH. Wide angle X-ray diffraction (WAXD) study also revealed that crystalline forms in both NCH and nylon 6 were the γ-form, and the crystallite size in NCH were larger than those in Nylon 6. Temperature dependence of dynamic viscoelasticity of NCH revealed that the magnitude of α_a-absorption for NCH was smaller than that of Nylon 6 suggesting the restriction of thermal molecular motion in NCH due to the strong ionic interaction between Nylon 6 and silicate layers. The fatigue strength for NCH was greater than that of Nylon 6 reinforced with short glass-fiber (N6/SGF) under the corresponding fatigue conditions, even though they showed almost the same magnitude of modulus. Fatigue fracture criterion based on energy loss dissipated for irreversible structural change was investigated for NCH, and it was revealed that the total viscoelastic energy loss dissipated for irreversible structural change up to fatigue failure of NCH was larger than those for Nylon 6 and (N6/SGF). This indicates that NCH has more superior fatigue characteristics than Nylon 6 and (N6/SGF).