Advanced torsional dynamic methods to study the morphology of uncured filled rubber compounds

Abstract

Uncured compounds of SBR1500 with various levels of silica were studied using a torsional dynamic tester (rubber process analyzer; RPA). Silica-filled compounds were prepared with the appropriate amounts (8.2%) of silane, i.e., bis(3-triethoxysilylpropyl)tetrasulfane (TESPT). A carbon black-filled compound was also studied for comparison. Strain sweep tests at constant frequency show that filled rubber materials exhibit either no or limited linear viscoelastic domain. Frequency sweep tests were performed either at the lowest strain amplitude or within the linear range at several temperatures; results were treated through time-temperature superposition in order to yield GЈ and GЉ master curves at the reference temperature of 100°C. Special test procedures were applied that are known to give interesting information about the morphology of complex polymer systems: the morphology damaging test (MDT) and the damaged morphology recovery test (DMRT). Results obtained are discussed with respect to the likely morphology of carbon black and silica-filled rubber compounds.

Some interesting phenomena in silica‐filled HNBR with the addition of silane coupling agent

“…After storage at room temperature for a month, the G ′ values of the compounds with and without KH570 at small strain amplitude shown in Figure 2 with hollow dots change differently. The G ′ value of the compound without KH570 increases, which can be explained by the traditional storage hardening phenomenon26 that filler will agglomerate to form filler network in storage period resulting in stronger Payne effect. During the storage time, as the interaction between silanol groups in silica surface is stronger than that between nitrile groups and silanol groups concluded from electronegativity order of oxygen atom and nitrogen atom, silica particles reagglomerated and Payne effect of the compound became stronger.…”

Finite Viscoelasticity of Particle-Reinforced Elastomers: the Effect of Filler Content

“…Equation (34) expresses the chain rule for differentiation of the vector function r = rðt; r 0 Þ with respect to r 0 . The right Cauchy deformation tensor, C, for transition from the initial state to the deformed state is given by…”

“…[3,12,16] According to the other approach, the viscoelastic behavior of filled rubbers at the macro-level is ascribed to rearrangement of strands in an elastomeric matrix, whereas the effect of particles and their aggregates is of second importance. This assumption is confirmed by observations: 1. in dynamic shear tests on uncured styrene-butadiene rubber reinforced with various amounts of carbon black and silica, [34] that reveal rather limited timedependent response compared with the response of vulcanized rubbers, 2. in dynamic tensile tests on ternary composite of poly-(propylene) and ethylene propylene diene monomers (EPDM) elastomer filled with glass beads, [35] that demonstrate that (i) treatment of beads by silane coupling agent does not affect mechanical damping and (ii) the loss modulus of the compound with untreated beads decreases with their volume fraction (in contrast with the concept of de-wetting of chains from filler particles). Our experimental data in tensile relaxation tests on natural rubber reinforced with high abrasion furnace black [36] demonstrate comparable decays in the longitudinal stress for a filled [45 phr (parts per hundred parts of rubber) of carbon black (CB)] and an unfilled compounds.…”

Analysis of Bulk Dynamic Properties in Two-Layered Natural Rubber Vulcanisates

“…For example, the vibration damp of a car tyre could be increased by increasing tan d. On the negative side, some parts of the dissipative energy, which are not easily conducted away, are transformed into heat and, therefore, deteriorate properties of rubber vulcanisates. Numerous works reveal that the hysteresis factor depends markedly on types of rubbers [8,9] , fillers [10][11][12][13][14][15][16] , the extent of interactions between filler and rubber matrix [10,17,18] , strain magnitude [11,17,19] , strain rate [10,11,17,19] , temperature [10,20] , state of cure [20] , and curing system [20][21][22][23] .…”