Composite processing and study of properties for polypropylene EPD60R/modified nanoclay Cloisite® 15A

Abstract

The effects of adding nanoclay to improve the thermal and mechanical properties of polypropylene (PP) copolymers grade (EPD60R) used in the pipe industry were investigated. To improve the dispersion of the nanoclay in the polymeric matrix, a 30 wt% of nanoclay master batch was first prepared by mixing PP matrix maleic anhydride PP oligomer (PP-g-MA) and Cloisite® 15A (C15A) nanoclay. The prepared master batch was used to produce nanocomposites with 2 and 5 wt% nanoclay. The nanocomposites were analyzed by XRD (X-ray diffraction), SEM (Scanning electron microscopy), DSC (Differential scanning calorimetry), TGA (Thermogravimetric analysis), and other mechanical tests. The XRD and SEM results indicated the occurrence of an intercalated layer structure in the nanocomposites. Thermal properties of the nanocomposites were investigated using DSC and TGA tests. The crystallinity of the 2 wt% nanoclay was improved by about 59.23% in the nanoclay reinforced samples. As the content of nanoclay increased, the composite exhibited higher thermal degradation temperature. Performing a limiting oxygen index (LOI) test on the samples showed that the addition of nanoclay to the EPD60R matrix increased the flame retardancy by 12.58%. The tensile modulus of the nanocomposites was improved compared to the pure polymer, while the elongation at break and at yield showed a reduction. To investigate the nanocomposite in pipe application, a pipe (external diameter 110.8 and thickness 3.65 mm) was manufactured in a special tube extruder machine with 2 wt% of C15A. Tests of the tube’s physical and mechanical properties indicated that its ring stiffness increased by 25% compared to the pure PP.