A study on attapulgite reinforced PA6 composites

Attapulgite (ATB)/PA6 (polyamide 6) composites with different ATB contents have been prepared by the melt compounding approach using a Brabender twin-screw extruder. Mechanical investigation (by tensile test and bending test) showed that yield strength reaches a maximum value with incorporation of 4 wt% ATB for the tensile test and with incorporation of 2 wt% ATB for the bending test. Scanning electron microscopy (SEM) observation on the fracture surfaces of the composites showed that a uniform dispersion of ATB is obtained. Dynamic mechanical analysis and the results of differential scanning calorimetry (DSC) reflected that there are strong interactions between ATB and PA6. SEM photographs of the fracture surface at different angles showed that the bundles of rod shaped crystals of ATB may orient along with the direction of melt flow during injection molding. X-ray diffraction (XRD) measurements suggested that the inclusion of ATB into PA6 matrix hardly changes the crystalline structures of both ATB and PA6. However, crystallite size of γ-form PA6 in PA6/ATB composites becomes much larger. Furthermore, the content of α-form PA6 gradually increases while the content of γ-form gradually decreases from surface to core for the injection molding samples.