Effect of Compatibilizer and Carbon Nanotubes on Blends of Polypropylene and Nylon 6

Abstract

The melt mixing of Polypropylene (PP) and Polyamide-6 (Nylon 6) results in a thermodynamically immiscible two phase system due to their high interfacial tension and poor adhesion. A compatibilizer namely Polypropylene grafted maleic anhydride (PP-g-MAH) is employed which encourages the formation of chemical linkages during reactive extrusion. In this study, PP/Nylon 6 blend ratio was maintained at 70/30. In addition to the compatibilizer, carboxylic acid functionalized multi walled carbon nanotubes (MWCNT) were added to the blend. The polymer blend prepared by twin screw extrusion was converted into test samples by injection moulding. The microstructure development of the blends was characterized by scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR) techniques. The mechanical and thermal properties of the blends were studied using tensile test and differential scanning calorimetry (DSC) respectively. The effective dispersion of nylon phase due to the presence of MWCNTs and PP-g-MAH was established by SEM analysis. FTIR spectra revealed the efficacy of the compatibilizer in producing cyclic imide groups in the blends. The simultaneous addition of compatibilizer and MWCNTs improved the tensile strength, elongation at break, modulus of elasticity and hardness of the PP/Nylon 6 blend. Both compatibilizer and MWCNTs act as nucleating agents for the crystallization of PP. The crystallization temperature of PP was shifted to higher temperatures in the presence of both compatibilizer and MWCNTs as observed from DSC analysis. The blend which contained 6% PP-g-MAH and 2% MWCNT exhibited optimum set of properties