Declining Performance of Silicone-Based Magnetorheological Elastomers after Accelerated Weathering

Abstract

Magnetorheological elastomers (MRE)-based products are usually located in an area directly exposed to sunlight and rain. However, there is no specific research on the behavior of MRE after accelerated weathering. Therefore, in this study, the changes to the chemical and rheological properties of both isotropic and anisotropic MRE after accelerated weathering were examined. Treated and untreated specimens were compared. MRE specimens with 40% by weight CIP were prepared with no current excitation and another sample was prepared with 1.5 T of magnetic flux density. Each specimen was treated in an accelerated weathering machine, Q-Sun Xe-1 Xenon Test Chamber, under a UV light exposure cycle and water spray. A material characterization was carried out using FTIR and a rheometer to determine the changes to the chemical and rheological properties. The morphological analysis results showed that after the weather treatment, the surface was rough and more cavities occurred. The rheometer test results showed a significant decrease in the storage modulus of each treated MRE specimen, unlike the untreated MRE specimens. The decrease in the storage modulus value with currents of 0, 1, 2, and 3 Amperes was 66.67%, 78.9%, 85.2%, and 80.5%, respectively. Meanwhile, FTIR testing showed a change in the wave peak between the untreated and treated MRE specimens. Thermogravimetric analysis (TGA) also showed a decrease in MRE weight for each specimen. However, for both treated and untreated MRE specimens, the decrease in TGA was not significantly different. In all the tests carried out on the MRE samples, weather acceleration treatment caused significant changes. This is an important consideration for developers who choose silicone as the MRE matrix.

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

“…Natural weathering in a tropical climate exhibited a distinct degradation process, with dry and wet conditions averaging 27.5 °C and 287.5 mm rainfall with 74.3% humidity, respectively. Previous research [ 17 ] on accelerated weathering of MRE found that the G’ decreased by up to 85% with increasing magnetic strength after the accelerated weathering condition. These findings, however, were established under much more aggressive conditions, such as a difference of 120% in temperature and at least a 20% difference in humidity in comparison to the current study.…”

“…The outdoors [ 15 ] is one of the most demanding service environments, with weather conditions having a strong correlation. Weathering [ 16 , 17 , 18 , 19 ] accelerates the undesirable change caused by outdoor exposure, and the climate atmosphere influences the weathering condition over relatively long periods. As the MRE industry has evolved, significant effort has been expended to understand the degradation of MRE during weathering in various climates, with the focus on tropical climates.…”

“…Weathering’s adverse consequences on MRE, in general, have been attributed to a complex set of processes involving environmental stress (photophysical and photochemical). The most recent study on MRE performance under weathering conditions by Wibowo et al [ 17 ] found that MRE microstructurally degraded and rheological properties were significantly reduced up to 80.5%. The UV and water degradation processes that occurred as a result of the breaking of the chain of particle bonds arranged in the MRE sample were also considered.…”