Study On Immiscible Polypropylene/SAN Blends And Partly Miscible Polypropylene/K-resin Blends Compatibilized By Nano-CaCO₃

The most convenient and universal methtod for compatibilization of polymer blends is introducing compatibilizer. So far almost all the compatibilizers used have been organic materials. In recent years, a new concept of compatibilization by using inorganic nano-particles, which instead of the conventional organic compatibilizer, has been proposed. This idea is of importance to the theoretical study, and possesses a profound prospect in industrial application.In this paper, the compatibilization of nano-CaCO₃ in immiscible PP/SAN blends and partly miscible PP/K-resin blends was studied by changing the content of nano-CaCO₃ and weight ratio of resin components, assembling of nano-CaCO₃ and SBS, and processing by different methods. The experiment results incated that the effect of nano-CaC03 in two systems above was distinct.For immiscible PP/SAN blends, the main work and conclusions were listed as following:(1) Not only in PP/SAN(70/30 , wt/wt)/nano-CaCO₃ systems but also in PP/SAN(50/50)/nano-CaCO₃ systems, the adding of nano-CaCO₃ decreased the size of dispersed SAN phase and improved the compatibility of systems. Increasing nano-CaCO₃ content, the compatibilization increased, and reached to optimization at 6phr. Then the nano-CaCO₃ concentration rised to 10phr, the compatibilization got worse. The reason for that was nano-CaCO₃ compatibilized the systems by improving interface adhesion, high concentration leaded to nano-CaCO₃ agglomeration.(2) Nano-CaCO₃ didn't meliorate the thermodynamic compatibility of PP/SAN blends, which indicated that the improved compatibilization resulted from rather a kinetics reason than thermodynamic one.(3) The different weight ratios of PP/SAN(70/30 and 50/50) had little effect on the compatibilization of nano-CaCO₃.(4) For PP/SAN(50/50)/nano-CaCO₃ systems, with the increase of nano-CaCO₃ content, Izod impact strength changed little, but tensile strength and yield strength somewhat increased. For PP/SAN(70/30)/nano-CaCO₃ systems, Izod impact strength, tensile strength and yield strength had ascending tendency as a whole.(5) The effect of three processing methods on PP/SAN(50/50)/nano-CaCO₃ systems were studied. In method 1, adding PP, SAN and nano-CaCO₃ into extruder simultaneously for blending twice. In method 2, PP composited with nano-CaCO₃ firstly, then the extrusion blended with SAN. In method 3, SAN composited with nano-CaCO₃ firstly, then the extrusion blended with PP. Three methods influenced the thermodynamic compatibility of systems little. Comparing to methed 1, in the samples prepared by method 2 and method 3, the size of phase domain was rough. Maybe three processing methods resulted in different ratio of viscosity for polymer components. For mechanical properties of systems, the best ones were the samples prepared by method 2, and the worest ones were the samples prepared by method 3.(6) The assembling of nano-CaCO₃ and SBS filled in PP/SAN(70/30) systems by two methods. In method 1, SBS composited with nano-CaCO₃ firstly, then blended with PP and SAN. In method 2, adding PP, SAN, SBS and nano-CaCO₃ into extruder simultaneously. In all systems, the total loading of nano-CaCO₃ and SBS were fixed at 10phr, and the weight ratio of nano-CaCO₃/SBS were 2:1, 1:1, 1:2. Among all systems, the best compatibilization was found in the PP/SAN(70/30) systems filled with 2:1 nano-CaCO₃/SBS by method 1. In the mass, the compatibility of systems filled with nano-CaCO₃/SBS by method 1 were better than that by method 2, which implied that there was some synergistic effect between nano-CaCO₃ and SBS. Additionally, for the nano-CaCO₃/SBS filled systems, Izod impact strength was higher than nano-CaCO₃ filled systems solely, tensile strength and yiels strength changed little.For partly immiscible PP/K-resin blends, the main work and conclusions were listed as following:(1) For PP/K-resin blends(70/30), with the addition of lphr nano-CaCO₃, the size of dispersed K-resin phase decreased remarkably, and distributed homogeneously. Then increasing nano-CaCO₃ content, the size of dispersed domain remain the level.(2) For PP/K-resin blends(70/30)/nano-CaCO₃ systems, with the increase of nano-CaCO₃ content, Izod impact strength took on ascending trend, tensile strength had some decrease, and yiels strength changed little.(3) The assembling of nano-CaCO₃ and SBS filled in PP//K-resin (70/30) systems by two methods, which was same to the operation in PP/SAN systems. Changing the weight ratio of nano-CaCO₃/SBS and adding method, the size of dipersed phase remain invariable, similar to the system filled with 10phr nano-CaCO₃. It implied that the synergistic effect which was observed in PP/SAN systems didn't exist in PP/K-resin systems.(4) For nano-CaCO₃/SBS filled systems, mechanical properities were influenced little by adding method. Comparing to nano-CaCO₃ filled systems solely, Izod impact strength had notable increase, tensile strength and yiels strength changed little.