Mechanical, thermal, morphological and flammability properties of halloysite nanotube reinforced compatibilized poly(ethylene terephthalate) / polypropylene nanocomosities

Abstract

The effects of two types of compatibilizers and halloysite nanotubes (HNT) on poly(ethylene terephthalate) (PET)/polypropylene (PP) blends were investigated. Blends of PET/PP in various compositions ranging from 20 – 50 wt% of PP were prepared via twin screw compounding. Polypropylene grafted maleic anhydride (PPg- MAH) and styrene-ethylene/butylene-styrene grafted maleic anhydride (SEBS-g- MAH) at composition 0 – 10 phr respectively were used as compatibilizers. Mechanical test showed that when PP was incorporated into PET, tensile modulus increased significantly. Both tensile and flexural strengths of the blends showed considerable improvement at 4 phr PP-g-MAH and the impact strength of the blends significantly increased at 8 phr of SEBS-g-MAH. Scanning electron microscopy micrographs confirmed the excess amount of compatibilizer induced agglomerations that limited the enhancement of the mechanical properties. PET/PP/PP-g-MAH 70/30/4 phr was chosen as the optimum composition for the next series of study. The incorporation of HNT into compatibilized blends increased all the mechanical properties. Thermogravimetric analysis data showed that the thermal stability of compatibilized PET/PP filled with HNT was higher than the unfilled blends, while the limiting oxygen index test showed that flammability decreased with the increasing amount of HNT. Transmission electron microscopy revealed that there were interactions between HNT and compatibilized PET/PP blend. X-ray diffraction analyses indicated limited intercalation of HNT occurred in PET/PP nanocomposites. Fourier transform infrared spectroscopy analysis showed the existence of hydrogen bonds between silicon monoxide of HNT with the polar groups of PET and PP-g- MAH. The optimum composition in terms of mechanical properties of compatibilized PET/PP filled HNT was achieved at 2 phr loading of HNT.