Temperature Dependent on Mechanical and Rheological Properties of EPDM-Based Magnetorheological Elastomers Using Silica Nanoparticles

Abstract

Temperature is one of the most influential factors affecting the performance of elastomer matrix in magnetorheological elastomer (MRE). Previous studies have utilized silica as a reinforcing filler in polymer composite and as a coating material in MRE to improve the thermal stability of the base material. However, the usage of silica as an additive in the thermal stability of MRE has not been explored. Thus, in this study, the effect of silica as an additive on the temperature-dependent mechanical and rheological properties of ethylene propylene diene monomer (EPDM)-based MREs was investigated by using 30 wt.% carbonyl iron particles (CIPs) as the main filler, with different contents of silica nanoparticles (0 to 11 wt.%). The microstructure analysis was examined by using field-emission scanning electron microscopy (FESEM), while the thermal characterizations were studied by using a thermogravimetric analyzer and differential scanning calorimetry. The tensile properties were conducted by using Instron Universal Testing Machine in the absence of magnetic field at various temperatures. Meanwhile, the rheological properties were analyzed under oscillatory loadings in the influence of magnetic field, using a rotational rheometer at 25 to 65 °C. The results revealed that the temperature has diminished the interfacial interactions between filler and matrix, thus affecting the properties of MRE, where the tensile properties and MR effect decrease with increasing temperature. However, the presence of silica capable improved the thermal stability of EPDM-based MRE by enhancing the interactions between filler and matrix, thus reducing the interfacial defects when under the influence of temperature. Consequently, the incorporation of silica nanoparticles as an additive in EPDM-based MRE requires more exploration, since it has the potential to sustain the properties of MRE devices in a variety of temperature conditions. Thus, the study on the temperature-dependent mechanical and rheological properties of MRE is necessary, particularly regarding its practical applications.

Thermo-rheological improvement of magnetorheological foam with the addition of silica nanoparticles

“…The result is in line with a recent study conducted by Rashid et al [21], who found that as the temperature increased from 25 • C to 65 • C, G 0 ′ of MRE has reduced from 0.76 to 0.63 MPa. It is due to the rising temperatures has provided kinetic energy to the molecular chains of polymer, thus allowing the particles to slightly move [21]. Therefore, in accordance with the dropped values of storage modulus of MR foams, it is expected that the rising temperatures also contributed to the increment in the kinetic energy of molecular chains of MR foam, resulting in the particles movement slightly.…”

“…Besides, a previous study of basic PU foam has stated that the changed in temperature during service performance have caused changes in the macroscopic properties of the material, such as loss in strength and modulus [30]. The result is in line with a recent study conducted by Rashid et al [21], who found that as the temperature increased from 25 • C to 65 • C, G 0 ′ of MRE has reduced from 0.76 to 0.63 MPa. It is due to the rising temperatures has provided kinetic energy to the molecular chains of polymer, thus allowing the particles to slightly move [21].…”

“…Commonly, the selection of additives would depend on the desired outcome and the application requirements. In the past studies of MR materials, the use of additives such as graphite [18], cobalt ferrite [19], carbon nanotubes (CNTs) [20] and silica [21] are employed to optimize the rheological, morphological, thermal, or mechanical characteristics of MR materials. In 2009, Li et al [18] found that the addition of graphite has significantly boosted the MRE's conductivity and decreased its resistance by over 85%.…”

“…Recently, the interest in the usage of silica nanoparticles as an additive has been further utilized in MR material, particularly in MRE to improve its respective thermal stability. For example, Rashid et al [21] proved that with 3-11 wt.% of silica nanoparticles, the thermal stability of the MRE has been shifted from 209 • C to 234 • C, showing the increased in the decomposition temperature of the material. Furthermore, the silica nanoparticles that acted as an adhesive has strengthened the matrix-filler interactions of MRE, and simultaneously enhanced the rheological properties [24].…”

Natural Weathering Effects on the Mechanical, Rheological, and Morphological Properties of Magnetorheological Elastomer (MRE) in Tropical Climate

“…Magnetorheological elastomer is known to be highly susceptible to temperature [ 7 , 8 ], humidity [ 9 ], heat [ 10 , 11 ], chemical attack [ 12 ], and moisture [ 13 ], all of which degrade performance [ 14 ]. Furthermore, while MRE properties can be degraded incrementally during fabrication, operation, and storage, environmental exposure can cause the most significant degradation.…”