Nanostructural Modification of Polyamide/MMT Hybrids under Isothermal and Nonisothermal Elongational Folw

The aim of this work is to investigate the effects of elongational flow on the nanoscale arrangement of the silicate inside polyamide-based nanocomposites. Hybrids, at different loadings of a commercial organoclay, were produced by melt compounding using two polyamide matrices, a nylon-6, and a copolyamide with similar molecular weight and rheological properties. The elongational flow characterization was performed under both isothermal and nonisothermal conditions by using, respectively, an elongational rheometer (SER) and a fiber-spinning technique. The extensional rheological response of melt-compounded nanocomposites, correlated to TEM and X-ray analyses, was used to probe the nanostructural modifications developed during the uniaxial stretching. The results demonstrated that isothermal and nonisothermal elongational flow can modify the nanomorphology of the nanocomposite hybrids affecting the degree of silicate exfoliation as well as the extent of silicate orientation upon the stretching direction. The entity of structural modifications induced by the stretching were highly dependent on the initial nanomorphological state and on the polymer-clay affinity.