Research On Mechanical Property Of PP/Nano-SiO₂ Composite Materials

The emergence of nanotechnology provides a new method and means for modification of polymers. This article investigates 1) the dosage and particle diameter of nano-SiO₂, 2) the processing technics with one-step method and two-step method,3) the influence of heat treatment temperature and coupling agent contents on such mechanic properties as the tensile strength, tensile modulus and the izod impact strength of nano-SiO₂/polypropylene composite materials; makes an investigation of the influence of the dosage of nano-SiO₂ on the Rockwell hardness of composite materials and makes an analysis about the section of the modification of polypropylene with nano-SiO₂ through scanning electron microscope.The results showed that the mechanical property was markedly improved and had a peak value When w(PP):w(SiO₂) was 100:4, hence the modification of PP with SiO₂ has a best dosage, which in general contains a percentage of 4% or so. PP composite materials stuffed with conventional SiO₂ powder are not as good as those stuffed with nano-SiO₂ in tensile strength, bending strength and impact strength. The pictures of impulse section SEM shows that the impulse sections of the composite materials are irregular, interlocked and adhere to one another. Nano-particles disperse in the matrix, when impacted by impulse force, there will be local distortions between nano-particles and the matrix connected with them so that the striking energies are absorbed. Extrude nano-SiO₂ and PP together with a ratio of 1:1 and add PP to make the second blend extrusion. Nano-particles disperse into the composite materials and increase their toughening efficiency. If heat treatment and stretching velocity and coupling agents are used in appropriately, the mechanical properties of nano-SiO₂ / PP compound system may be enhanced. The Rockwell hardness of the composite materials will decrease at first and then increase with the increment of nano-SiO₂.