Properties Of Silicone Rubber Materials Research Articles

Analysis of High-Temperature Wideband Dielectric Properties of ATH-Filled Silicone Rubber Used for On-Site Insulation of Bare Overhead Conductors

Due to its excellent electrical and mechanical properties, and easy to cure at room temperature, room temperature vulcanizing silicone rubber is currently used in the on-site insulation of bare overhead conductors in the distribution system. The dielectric properties of silicone rubber materials have a great impact on power loss, which is vital to the transmission lines. Therefore, in this article, the dielectric properties of silicone rubber with the addition of different aluminum hydroxide contents are investigated by broadband dielectric spectroscopy in wide broadband range and wide temperature ranges, and the influence of aluminum hydroxide filler on the dielectric response is analyzed using a modified Cole–Cole model which takes the low-frequency dispersion process into account. It is found that the relationship of the dc conductivity and the low-frequency dispersion strength with temperature follows the Arrhenius equation law. The low-frequency dielectric response is influenced by dipoles’ polarization and electrode polarization. Moreover, the relaxation time decreases with the increase in temperature, and its mechanism can be revealed by the double-well model. The characteristic parameters obtained in this article can provide a reference for on-site insulating of bare overhead conductors.

Preparation and properties of silicone rubber materials with foam/solid alternating multilayered structures

In this paper, silicone rubber materials with foam/solid alternating multilayered structures were successfully constructed by combining the two methods of multilayered hot-pressing and supercritical carbon dioxide (SCCO2) foaming. The cellular morphology and mechanical properties of the foam/solid alternating multilayered silicone rubber materials were systematically studied. The results show that the growth of the cell was restrained by the solid layer, resulting in a decrease in the cell size. In addition, the introduction of the solid layer effectively improved the mechanical properties of the microcellular silicone rubber foam. The tensile strength and compressive strength of the foam/solid alternating multilayered silicone rubber materials reached 5.39 and 1.08 MPa, which are 46.1% and 237.5% of the pure silicone rubber foam, respectively. Finite element analysis (FEA) was applied and the results indicate that the strength and proportion of the solid layer played important roles in the tensile strength of the foam/solid alternating multilayered silicone rubber materials. Moreover, the small cellular structures in silicone rubber foam can provided a high supporting counterforce during compression, meaning that the microcellular structure of silicone rubber foam improved the compressive property compared to that for the large cellular structure of silicone rubber foam.

Biofunctionalization of silicone rubber with microgroove-patterned surface and carbon-ion implantation to enhance biocompatibility and reduce capsule formation.

PurposeSilicone rubber implants have been widely used to repair soft tissue defects and deformities. However, poor biocompatibility can elicit capsule formation, usually resulting in prosthesis contracture and displacement in long-term usage. To overcome this problem, this study investigated the properties of silicone rubber materials with or without a microgroove-patterned surface and with or without carbon (C)-ion implantation.Materials and methodsAtomic force microscopy, X-ray photoelectron spectroscopy, and a water contact angle test were used to characterize surface morphology and physicochemical properties. Cytocompatibility was investigated by a cell adhesion experiment, immunofluorescence staining, a Cell Counting Kit-8 assay, and scanning electron microscopy in vitro. Histocompatibility was evaluated by studying the inflammatory response and fiber capsule formation that developed after subcutaneous implantation in rats for 7 days, 15 days, and 30 days in vivo.ResultsParallel microgrooves were found on the surfaces of patterned silicone rubber (P-SR) and patterned C-ion-implanted silicone rubber (PC-SR). Irregular larger peaks and deeper valleys were present on the surface of silicone rubber implanted with C ions (C-SR). The silicone rubber surfaces with microgroove patterns had stable physical and chemical properties and exhibited moderate hydrophobicity. PC-SR exhibited moderately increased dermal fibroblast cell adhesion and growth, and its surface microstructure promoted orderly cell growth. Histocompatibility experiments on animals showed that both the anti-inflammatory and antifibrosis properties of PC-SR were slightly better than those of the other materials, and there was also a lower capsular contracture rate and less collagen deposition around implants made from PC-SR.ConclusionAlthough the surface chemical properties, dermal fibroblast cell growth, and cell adhesion were not changed by microgroove pattern modification, a more orderly cell arrangement was obtained, leading to enhanced biocompatibility and reduced capsule formation. Thus, this approach to the modification of silicone rubber, in combination with C-ion implantation, should be considered for further investigation and application.