Exfoliation Kinetics of a Phyllosilicate‐Organoclay Structure in a Polymer Matrix during Melt‐Extrusion Process

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Abstract
Nanostructured polymer‐composite materials were prepared by melt‐exfoliating the smectite structure of a synthetic tetrasilisic fluoromica in a nylon‐12 matrix, by means of a melt‐extrusion process using a single‐screw extruder. The structure and morphology of these materials were evaluated using the X‐ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Uniform dispersion of exfoliated slicate layers were observed throughout the polymer matrix. Rheological studies using a dual capillary rheometer showed that the melt viscosity of the nanocomposites was dependent on the degree of clay exfoliation, and in addition the orientation of the layered‐silicates in the polymer matrix. The exfoliation and orientation of layeredsilicates were in turn dependent on the processing conditions adopted. Typically a lower processing shear would improve the intercalation of the layered‐silicates while increasing shear enhanced their exfoliation. Improved exfoliation was shown to decrease the polymer melt viscosity, which may be attributed to the plasticising effect of the clay platelets.