The effect of silane coupling agent on iron sand for use in magnetorheological elastomers Part 1: Surface chemical modification and characterization

Abstract

Bis-(3-triethoxysilylpropyl) tetrasulphane (TESPT) was employed for surface modification of iron sand for use in magnetorheological elastomers (MREs). The amount of TESPT was varied at five levels (2,4,6,8 and 10wt%) relative to iron sand content to assess the optimum amount of coupling agent for interfacial bonding and damping performance. Evidence that coupling had occurred between iron sand and TESPT was identified by Raman Spectroscopy and the grafting percentage was determined by thermogravimetric analysis. Subsequently, isotropic MREs containing unmodified and modified iron sand particles and natural rubber were prepared. Crosslink density assessment by swelling testing provided evidence that the tetrasulphane group of TESPT formed crosslinks with the rubber chains. The results exhibited the advantages of TESPT as a coupling agent between iron sand particles and rubber and also revealed that 6% TESPT content produced the highest crosslink density. The effects of the amount of TESPT on dynamic mechanical properties the morphological characteristics of the MREs were also investigated.

Investigation and modelling of damping mechanisms of magnetorheological elastomers

“…The disparity of predicted damping capacity of MREs, and experimental tan δ is not surprising when all the assumptions of the model (previously described separately in the sections for different mechanisms) are considered which are summarized as follows: (although is accepted for viscous damping, this has not been previously shown to cover all mechanisms in MREs). The viscous damping of MREs follows the linear Kelvin Voight model. In reality, however, nonlinearity could occur due to addition of iron sand particles in the rubber matrix would changes the viscoelastic characteristics of the rubber. Iron sand particles were assumed to be spherical with the same diameter, however, the particles were not perfectly spherical or having the same diameter due to the milling process during preparation of iron sand as previously discussed in “Materials” section. In magnetism induced damping, the energy absorbed through magnetomechanical damping was considered insignificant due to the energy losses due to change of the magnetic domain structure is very difficult to directly measured. The iron sand particles are assumed to be aligned in long chains, however, the particles were not perfectly aligned in long chains during curing process under an applied magnetic field as reported elsewhere …”

“…The aim of the current work was to accurately predict total damping capacity of MREs and verify the relative important of different damping mechanisms to the total damping capacity of previously developed MREs based on iron sand and natural rubber taking account the separate mechanisms that would contribute to damping, namely: Viscous flow of the rubber matrix, Interfacial damping through strongly bonded interfaces and weakly bonded interfaces, Magnetic‐induced damping. …”

Influence of ionic liquid on the polymer–filler coupling and mechanical properties of nano‐silica filled elastomer

“…The specimens were immediately weighed on an analytical balance and then dried in a vacuum oven until the samples became constant weight and reweighed. The calculation was made according to the following equation: where w 1 is the weight of sample at swollen equilibrium with stable weight in analytical balance, w 2 is the weight of dried sample after swollen. χ 1 is the Flory‐Huggins NR–toluene interaction parameter (0.393), V is the molar volume of the toluene (106.4 cm 3 mol −1 ), ρ s and ρ d are the densities of the toluene (0.866 g cm −3 ) and the rubber (0.910 g cm −3 ), respectively.…”

Comparison of dynamic properties of magnetorheological elastomers with existing antivibration rubbers

“…(a) (b) In this study, isotropic and anisotropic MREs based on natural rubber and silane modified iron sand particles were prepared. The natural rubber was used as a matrix because of its associated ease of processing and good damping performance [14][15][16] and iron sand was chosen as magnetic particles because it has high permeability and saturation magnetisation, low cost and is readily available in New Zealand. Surface modification of iron sand using silane coupling agent was found to provide coupling between iron sand and natural rubber [15].…”

“…The natural rubber was used as a matrix because of its associated ease of processing and good damping performance [14][15][16] and iron sand was chosen as magnetic particles because it has high permeability and saturation magnetisation, low cost and is readily available in New Zealand. Surface modification of iron sand using silane coupling agent was found to provide coupling between iron sand and natural rubber [15]. It has also been reported that the silane modified particles decrease the interfacial tension around the particles and results in improved dispersion of magnetic particles in isotropic MREs and an improved degree of magnetic particle alignment in anisotropic MREs [16,17].…”