Study On The Structure And Properties Of Nylon / Polypropylene Blends

Polyamide-polypropylene (PA/PP) blends are interesting from an industrial point of view because they represent an economic and versatile method to modify the basic properties of the polymers, combining the thermomechanical properties of PA with the easy processability of PP. Potential advantages expected from blending the two components are:low absorption of humidity, better processability, good impact resistance, higher flexural modulus. Unfortunately they are incompatible due to the different polarity and to the different crystalline structure; mixing two thermodynamically immiscible polymers like PP and PA leads to incompatible blends with low mechanical properties.In order to improve the mechanical properties and compatibility of PA66/PP blends, the PA66/PP blends were prepared by melt compounding using a twin screw extruder, and analyzed by means of SEM and DSC. The effects of PA66content on mechanical properties, melt processability and morphology of PA66were investigated. Appropriate PA66content can improve the impact strength, melt processability and crystallization of PP. When the content ratio of PA66is10wt%, the melt index of PA66/PP composites increases by223%、the impact strength of the PA66/PP composites increases by42.6%compared with those of pure PP. The tensile properties of the PA66/PP composites decrease due to the poor compatibility of PP and PA66compared with those of pure PP.Nano-CaCO3and maleic anhydride-grafted ethylene-octene copolymer (POE-g-MA) were added to improve the stiffness and toughnes of PA66/PP composites. The results demonstrate that appropriate nano-CaCO3content can improve the melt processability, toughnes and rigidity of PA66/PP composites. A small amount of nano-CaCO3as a nucleating agent to produce a heterogeneous nucleation to accelerate crystallization of PP in the composites. The dispersed POE-g-MA inside the PA66/PP and nano-CaCO3/PA66/PP composites seem to hinder the diffusion process, hamper crystal formation of PP. POE-g-MA can improve the compatibility and interfacial adhesion between PP and PA66. Appropriate POE-g-MA content can obviously improve the impact strength and elongation at break of PA66/PP composites.The nano-CaC03/POE-g-MA/PA66/PP composites were prepared by melt compounding using a twin screw extruder and analyzed by DSC, SEM and mechanical testing. The results demonstrate that the better comprehensive properties were obtained for the PA66/PP composites with8wt%nano-CaCO3and6wt%POE-g-MA. The good comprehensive properties of the nano-CaCO3/POE-g-MA/PA66/PP composites mainly result from possible chemical interactions between PA66、POE-g-MA and PP.