Double networking vulcanizates

D-TEM gave 3D images of nano-filler dispersion in NR, which clearly indicated aggregates and agglomerates of carbon black leading to a kind of network structure in NR vulcanizates. That is, filled rubbers may have double networks, one of rubber by covalent bonding and the other of nanofiller by physical interaction. The revealed 3D network structure was in conformity with many physical properties, e.g., percolation behavior of electron conductivity. 

Aprem, A. S. Joseph, K. Thomas, S., Studies of Double Networks in Natural Rubber Vulcanizates. J.Appl. Polym. Sci. 2004, 91,1068-1076. 

The nonlinear viscoelastic behavior of filled vulcanizates is somewhat different from that of filled compounds, since the chemical crosslink network of the rubber matrix is formed and, the physical rubber-filler networks and filler-filler networks are enhanced during curing at a relatively high temperature [7]. Speaking from a broad sense, filled vulcanizates can be viewed as a double network structure in which the nanoparticles supplement the inherent viscoelasticity of crosslink rubbers with additional physical network junctions. 

Hamed GR, Huang MY (1998) Tensile and tear behavior of anisotropic double networks of a black-filled natural rubber vulcanizate. Rubber Chem Technol 71(5) 846-860... 

Aprem AS, Joseph K, Thomas S (2004) Studies on double networks in natiual rubber vulcanizates. J Appl Polym Sci 91(2) 1068-1076... 

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