Preparation And Properties Of Polyolefin/HNTs Nanocomposites

Impact polypropylene copolymer and metallocene polyethylene are important polyolefin materials,but their applications are limited due to their disadvantages such as low rigidity,low thermostability and so on.Polyolefin modification filled with inorganic fillers is one simple and affordable way to broaden and deepen their application fields.The research hotspot of filling modification is how to implement reducing the production cost and further the comprehensive performance of materials at the same time with addition of inorganic fillers.In this paper,with calcium carbonate(CaCO3)and magnesium hydroxide(MH)as main fillers,new nano-filler halloysite nanotubes(HNTs)as auxiliary filler,polyolefin resins were filled with micro-nano inorganic fillers to prepare HNTs/CaC03/IPC and HNTs/MH/mPE/POE nanocomposites by means of melt blending,respectively.Meanwhile,HNTs were surface modified through the methods of chemical modification and adding compatilizers,and the effects of quantity of filler and modification methods of HNTs on composite materials were studied.(1)HNTs/CaC03/IPC composites were prepared by the double-screw extruder and injection molding,and the mechanical and thermal properties of the composites were studied.The scanning electron microscopy(SEM)was used to observe the fractured surfaces of the composites,and the transmission electron microscopy(TEM)was used to observe the dispersion of inorganic particles.The results showed that not only the impact strength and the rigidity but also the thermal stability of the composites have been evidently increased by filling of HNTs and CaCO3 at the same time.When the mass fraction of HNTs is 2.0%,inorganic particles in the matrix have good dispersibility and good interface bonding with the matrix.Meanwhile,the impact properties of the composites filled with hydrophobic surface modified HNTs(m-HNTs)can further improved.(2)MH/mPE/POE and HNTs/MH/mPE/POE composites were prepared by the two-roll mill and compression molding,their mechanical properties,flame retardant properties and thermal properties were studied by the means of mechanical properties testing,limit oxygen index(LOI),thermo-gravimetric analysis(TGA).The field emission scanning electron microscopy(FE-SEM)was used to observe the morphology of the fractured surface and carbon layer of the composites.The result show that:with the increasing of the filling amount of MH,the limit oxygen index of MH/mPE/POE composites has been increased,but their mechanical properties decreased seriously.When the filled amount of HNTs was 1wt%,the oxygen index of HNTs/MH/mPE/POE composites has been increased from 31.6%to 33.6%,and their tensile strength improved.It has outstanding effect on improving the comprehensive performance of the composite systems filled with micro-nano composite fillers.The thermal properties and the morphology demonstrated that inorganic particles in the matrix have good dispersibility with proper filling quantity and revealed that the synergistic effect of HNTs stemmed from increasing effectively the thermal stability of the composites and the density of carbon residue after combustion.(3)With POE-g-MA,POE-g-GMA,LLDPE-g-MA and EVA-g-MA as compatibilizers,mPE/compatilizer/HNTs composites were prepared by melt blending and injection molding.By mechanical properties testing and X-ray diffraction(XRD),it suggested that the polar groups of the compatilizers can react with the surface hydroxyl of HNTs to improve the interfacial bond between HNTs and matrix resin,to increase their mechanical properties.The effect of adding POE-g-MA on mechanical properties,rheological properties,morphology and thermal properties of HNTs/POE-g-MA/mPE composites was observed.The results showed that POE-g-MA enhanced the interfacial bond between HNTs particles and mPE matrix,improved the distribution and dispersion of HNTs in the matrix.The tensile strength and elongation at break of the composites were increased simultaneously,showing the good reinforcing and toughening effect in the ternary composites.The storage modulus(G’)and complex viscosity(η*)have been increased,because HNTs has the more effect on restriction of the polymer chain mobility at the same HNTs content.Moreover,the thermal stability of the composite has improved with the addition of POE-g-MA.