Morphological parameters of PP/PA6 blend measured in-line during extrusion

An optical detector, assembled at a slit die at the exit of a twin screw extruder was used to quantify in-line the extrusion of a PP/PA6 immiscible blend. During the extrusion the detector respond according to the changes in concentration and particle size of the polyamide 6 phase. The influence of dispersed phase concentration was evaluated varying its concentration from 0 to 5% (w/w). Reduction in the PA6 particle size was followed adding different amounts of polypropylene grafted with acrylic acid (PP-g-AA), which acts as a compatibilizer. The normalized detector signal intensity increases with an increase in PA6 concentration, due to an increase in the number of scattering particles in the medium, and with a decrease in its particle size. Plots of detector signal as a function of particle concentration and size enabled the calculation of the extinction cross sections of the PA6 segregated particles.