A capacitance study of anomalous diffusion of water into HTV silicone rubber materials

Diffusion of Liquid Water in Free-Standing Polymer Films Using Pressure-Contact Time-Resolved Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy

“…This was initially unexpected since the glass transition temperature of PIB is well below the experimental temperature (room/ambient temperature) and Fickian behavior is typically observed for the diffusion of small molecules in rubbery polymers. However, several past studies have also shown non-Fickian behavior specifically for the diffusion of liquid water in rubbery polymers. − Gao et al , observed non-Fickian behavior for the diffusion of liquid water in silicone rubber films. They attributed the non-Fickian behavior to the presence of two states of water, “free” and “bound” water, and their interactions with silicone rubber. , Sundfors et al used conventional FTIR-ATR spectroscopy to study liquid water diffusion in silicone rubber mixtures.…”

Moisture Barrier Properties of Silicone Rubber Surface Layers Fluorinated at Different Temperatures

“…It can be noted in Figure 1 that the absorption characteristic of the virgin samples is a two-stage growth process under all humidity and temperature conditions. At the beginning of moisture absorption, the weight gain increases rapidly, and then the increase slows down to an equilibrium value, although the saturated absorption is not actually achieved even after 500 h. The absorption characteristic of the virgin sample appears to be that of the Langmuir type model [7]. Indeed, as shown also in Figure 1, the moisture absorption data are well fitted by the Langmuir model using the Equation (3), with the fitting parameters summarized in Table 1.…”

“…The former is the dissolved water molecules in the polymer matrix, and the latter is the constrained water molecules at hydrophilic regions or the Langmuir sites. The relative weight gain in the Langmuir type model can be given as Equation 3 [7,17], which has been successfully used to describe the diffusion of water molecules in SIRs [7].…”

“…Consequently there may be considerable interactions between water molecules and polymeric materials, associated with the formulation of polymeric materials. Due to the presence of hydrogen bonds between water molecules and fillers, the filler content in the SIR material has a significant influence on the diffusion and absorption of water [7]. In addition, the immersion of SIR in NaCl solution or HNO 3 solution would lead to the filler particles falling off the material, due to the interface failure between the fillers and the SIR matrix by the swelling and hydrolysis of the matrix or the chemical reaction with the matrix and fillers [8].…”

Effects of liquids immersion and drying on the surface properties of HTV silicone rubber: characterisation by contact angle and surface physical morphology

“…Based on actual operating experience of HTV silicone rubber composite insulator, water (from relative humidity, spray, and rain), salt solution (from dissolving of soluble matter in contamination), and nitric acid solution (generated from the discharge around the composite insulator in the presence of water, oxygen, and nitrogen) are three kinds of liquid that HTV silicone rubber composite insulator most commonly encounter during operation [13, 16]. These liquids can permeate into HTV silicone rubber by diffusion process accompanied by chemical interaction and physical dissolution processes, our previous research [13, 17] showed that there was no unified diffusion model (such as Fick diffusion model or Langmuir diffusion model) to describe all these diffusion processes of liquids into HTV silicone rubber due to the fact that chemical reaction and physical dissolution complicated the diffusion processes significantly. Furthermore, the changes of surface chemical properties of HTV silicone rubber caused by liquids diffusion can be characterised from two aspects, one was the change of polymer matrix and the other one was the change of inorganic filler (mainly the ATH filler) beneath and/or on the surface [18].…”