Differential Dynamic Modulus of Carbon Black Filled, Uncured SBR in Single-Step Large Shearing Deformations

Abstract

Correspondence between nonlinear viscoelastic properties and change in various networks in carbon black (CB) filled, uncured SBRs has been studied by using combined measurements of relaxation modulus, differential dynamic modulus, and volume resisitivity in wide range of filler concentrations at various shear strains. Volume resistivity at no deformation showed step-off like change which can be explained by the percolation theory. This indicates formation of contact filler network at high filler loading. In addition, change in volume resistivity showed clear correspondence with linear-nonlinear transition in viscoelasticity. By the use of simple three-network model, contributions of contact filler, bridged filler, and entanglement networks to relaxation modulus were estimated. It was found that contact filler and bridged filler networks were dominant at lower and at higher filler concentrations, respectively. It was proposed, furthermore, that differential dynamic modulus can be used as the probes for changes in contact filler and bridged filler networks, respectively.

Filler Network Recovery of Carbon Black Filled Rubber

“…The knowledge leads us to the idea that the change in carbon black network occurs in large deformations and it leads nonlinearity in viscoelastometry. This plausible idea has been confirmed in electric resistance measurements of filled rubbers 6) and 3D-TEM observation of filled rubbers cured in deformed states 23) .…”

“…This strain-sensitive nature may be due to filler effect. Recently existence of filler network in filled rubbers has been recognized experimentally not only in macroscopic scale by rheometry in reversing double-step deformations 16) , and differential dynamic modulus 6) , but also in microscopic scale by in-situ microscopy 17,18) and 3D-TEM [19][20][21][22] . The knowledge leads us to the idea that the change in carbon black network occurs in large deformations and it leads nonlinearity in viscoelastometry.…”

“…The nonlinearity observed in unfilled polymer is much weaker than that in filled rubber [6][7][8][9][10][11][12][13][14][15] . For example, unfilled polymers show linear viscoelastic behaviors even at shear strain =0.1 [8][9][10][11][12][13] , while filled rubbers show nonlinear viscoelastic behaviors at shear less than =0.01 6,7,14,15) . This strain-sensitive nature may be due to filler effect.…”

Nonlinear Viscoelasticity of Rubber Materials: Payne Effect and Differential Dynamic Modulus

“…DDM for filled, cured samples 3 and 4 shows g L dependence similar to that for unfilled, cured samples. But GЉ shows additional energy dissipation probably due to filler network rupture, 3,4) resulting in high values in tand at larger strain amplitude. It may be noted that there is clear difference between nonlinear behaviors for tand(w, g L ; t) in unfilled and in filled samples.…”

“…Hence nonlinear viscoelasticity is important for characterization of rubber materials. 3,4) Rubber materials are made of two networks, chemical and physical networks. In a physical network, filler plays an important role.…”