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Typically, the dispersed phase silicon dioxide in rubber is measured from one hundred nanometers to several microns, and the particle diameter of monodisperse silica particles have several nanometers to several tens of nanometers (referred to as a minimum monodispersed silica particles). So small and monodisperse silica particles of large specific surface area, arguably the reinforcing effect should be better, but the tear strength of the vulcanized rubber are generally lower than silica-filled rubber. The current theory is the diameter of the reinforcing nanoparticles nanoparticles smaller, the more the number of surface atoms, the more unpaired atoms, and there are many dangling bonds, unsaturated properties, easy to combine with other atoms, which can closely integrated with the polymer molecules, better compatibility, can effectively withstand the force transfer, triggering matrix yielding, consume large amounts of impact energy, thereby reinforcing, toughening polymers. The reinforcing effect with nanoparticles of monodisperse silica particles reinforcement theory seems to be contradictory, it is worth exploring. Carbon black and silica since its inception has served as a rubber reinforcing agent, had never presented a single form of dispersed nanoparticles, but in the form chain-like aggregates of nanoparticles dispersed in the rubber matrix, people have been trying to study Strengthening mechanism of carbon black and silica. 20th century, there microstructure and mechanical properties of nano-particle chains of some scientists carbon black and silica particle surface, in order to find direct evidence for improving the tensile strength and elastic modulus of carbon black and silica-filled rubber, also help to answer the above questions.

Elasticity Attribute 1 nanometer roughness and particle chains particle surface:

In describing the aggregate fumed silicon dioxide or carbon black primary particles, commonly rough, fused or sintered, necking respectively describe the particle surface, combined with the shape of the particles at the juncture between the particles, indicating strong aggregates rough topography and extent of the particle surface. It should be noted that the combination of primary particles between two ways: on the chain between adjacent particles are strong chemical bond; is weakly bound van der Waals forces (ie nanoparticle chain decentralized basis except between particles ). Three-dimensional structure of fumed silica shown in Figure 1.

To reflect the scanning tunneling electron microscope N330 carbon black particle surface microstructure (STM) photograph shown in Figure 2. It has been observed that the surface morphology of nanoparticles are atomic steps, uneven, rough structure, the higher the amount of its silicon atomic step edges and corners, a larger activity, easy and some of the polymer chains with strong chemical and physical action. When subjected to external forces, which can be dispersed carbon black N330 Figure 2 of STM photos to share the burden of another polymer chain, the polymer network will not be quickly destroyed. At the same time, the surface of the silicon atoms in silica particles-active steps, between particle aggregation prone curled to reduce its surface free energy between particles is stronger, easy to form aggregates. The monodispersed silica particles of nano smooth surface action between the particles is weak, dispersed in the rubber matrix as "micro-nano ball" between the molecular chains dispersed, a lubricant, favor intermolecular chain relative motion. It may be filled with monodisperse nano silicon dioxide particles can improve the vulcanized rubber tensile strength and elongation at break, rubber increased liquidity reasons.


 

 

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