Compatibility of liquid and solid insulation materials for high voltage subsea connectors

The main objective of this study is to identify reliable insulation materials and systems for novel AC and DC subsea power connectors for oil and gas exploitation. A combined solid-liquid insulation system might be radically altered if the materials are not compatible. Different combinations of relevant solid and liquid insulation materials were exposed to well defined and realistic subsea (and atmospheric) conditions, and potential material alterations were thoroughly examined with respect to ageing for up to three years. Mechanical and thermal properties have been characterized for poly(ether ether ketone) (PEEK), silicone rubber and epoxy aged in a synthetic ester. No profound effect of hydrostatic pressure was found, however the effect of increased humidity in the ester in combination with elevated temperature is dramatic for epoxy and silicon rubber.Compatibility of liquid and solid insulation materials for high voltage subsea connectorsacceptedVersio

A novel bench size model coalescer: Dehydration efficiency of AC fields on water-in-crude-oil emulsions

We describe herein the design of a small AC electrostatic model coalescer for investigating coalescence efficiency of water in oil emulsions. The function of the model coalescer is tested on emulsions with different water cuts. In the coalescer, coalescence takes place in a couette flow in the bulk emulsion. The electric field has a high utilization factor, and the electrodes are insulated to avoid drop charging. The set-up allows for independent setting of retention time and shear rate of the emulsion. Temperature can be adjusted up to 80 °C, and AC voltage level, frequency and shape can be varied. Efficiency is measured optically and by checking speed of water precipitation. Several parameters have been studied to determine their influence on the electrostatic dehydration process of water-in-crude-oil emulsions. Temperature, wave form, water content, droplet size but also rotational speed were found to play an important role in the process according to what was expected theoretically. © IEEEacceptedVersio

Epoxy-Based Nanocomposites for High-Voltage Insulation: A Review

Epoxy nanocomposites, with inorganic oxide nanoparticles as filler, can exhibit novel property combinations, such as enhanced mechanical strength, higher thermal conductivity, increased dielectric breakdown strength, and reduced complex permittivity. Therefore, they have interesting applications in nanodielectrics, such as high-voltage insulation materials or in microelectromechanical systems. The primary challenge in the processing of nanocomposites is achieving a homogeneous dispersion of the nanoparticles. The dispersion quality affects the interfaces between the organic and the inorganic components, which can determine the final properties of the nanocomposite. Here, the processing methods and the resulting dielectric, mechanical, and thermal properties of epoxy nanocomposites with inorganic oxide fillers are presented. Functionalization of the nanoparticle generally improves the dispersion of the particles in the polymer matrix. Different oxide fillers are observed to have similar effects on the properties of the nanocomposites. Epoxy-based nanocomposites exhibit improved dielectric breakdown strength and lower complex permittivity with inorganic oxide nanoparticles at low filler contents, compared to conventional composites with micrometer-sized particles. While there are some inconsistencies in the findings, which may be attributed to differences in the dispersion quality, an improved understanding of the nanoparticle–epoxy interfaces in nanocomposites will enable tailoring of the desired properties, opening new avenues for application.Epoxy-Based Nanocomposites for High-Voltage Insulation: A ReviewsubmittedVersio

Compatibility of liquid and solid insulation materials for high voltage subsea connectors

The main objective of this study is to identify reliable insulation materials and systems for novel AC and DC subsea power connectors for oil and gas exploitation. A combined solid-liquid insulation system might be radically altered if the materials are not compatible. Different combinations of relevant solid and liquid insulation materials were exposed to well defined and realistic subsea (and atmospheric) conditions, and potential material alterations were thoroughly examined with respect to ageing for up to three years. Mechanical and thermal properties have been characterized for poly(ether ether ketone) (PEEK), silicone rubber and epoxy aged in a synthetic ester. No profound effect of hydrostatic pressure was found, however the effect of increased humidity in the ester in combination with elevated temperature is dramatic for epoxy and silicon rubber

Epoxy-Based Nanocomposites for High-Voltage Insulation: A Review

Epoxy nanocomposites, with inorganic oxide nanoparticles as filler, can exhibit novel property combinations, such as enhanced mechanical strength, higher thermal conductivity, increased dielectric breakdown strength, and reduced complex permittivity. Therefore, they have interesting applications in nanodielectrics, such as high-voltage insulation materials or in microelectromechanical systems. The primary challenge in the processing of nanocomposites is achieving a homogeneous dispersion of the nanoparticles. The dispersion quality affects the interfaces between the organic and the inorganic components, which can determine the final properties of the nanocomposite. Here, the processing methods and the resulting dielectric, mechanical, and thermal properties of epoxy nanocomposites with inorganic oxide fillers are presented. Functionalization of the nanoparticle generally improves the dispersion of the particles in the polymer matrix. Different oxide fillers are observed to have similar effects on the properties of the nanocomposites. Epoxy-based nanocomposites exhibit improved dielectric breakdown strength and lower complex permittivity with inorganic oxide nanoparticles at low filler contents, compared to conventional composites with micrometer-sized particles. While there are some inconsistencies in the findings, which may be attributed to differences in the dispersion quality, an improved understanding of the nanoparticle–epoxy interfaces in nanocomposites will enable tailoring of the desired properties, opening new avenues for application

The Structure, Morphology, and Complex Permittivity of Epoxy Nanodielectrics with in Situ Synthesized Surface-Functionalized SiO2

publishedVersio

In situ synthesis of epoxy nanocomposites with hierarchical surface-modified SiO2 clusters

Polymer nanocomposites are often produced using in situ approaches where an inorganic filler (as the dispersed phase) is synthesized directly in an organic matrix. Such an approach generally leads to improved dispersion and reduced agglomeration of the filler material. Epoxy-based nanocomposites have demonstrated promising properties for application as high-voltage insulation materials. In this work, a sol–gel based method has been adapted to synthesize surface-functionalized SiO2 in situ in epoxy. The synthesized SiO2 moieties were dispersed in clusters of 10–80 nm, and formed chemical bonds with the epoxy monomers via a silane coupling agent. Raman spectra show the formation of four-membered D1 rings, which may be part of a cage-like structure similar to that of polyhedral oligomeric silsesquioxanes (POSS). SAXS measurements indicate that the SiO2 clusters consist of a hierarchical structure with an increasing fractal dimension with increasing SiO2 content. The nanocomposites displayed improved thermal stability, while the glass transition behavior varied depending on the structure and content of the SiO2 moieties. While the relative permittivity showed no significant changes from that of pure epoxy, the onset of the dielectric relaxation changed with the SiO2 structure and content, similar to the behavior observed for the glass transition

The Structure, Morphology, and Complex Permittivity of Epoxy Nanodielectrics with in Situ Synthesized Surface-Functionalized SiO2

Epoxy nanocomposites have demonstrated promising properties for high-voltage insulation applications. An in situ approach to the synthesis of epoxy-SiO2 nanocomposites was employed, where surface-functionalized SiO2 (up to 5 wt.%) is synthesized directly in the epoxy. The dispersion of SiO2 was found to be affected by both the pH and the coupling agent used in the synthesis. Hierarchical clusters of SiO2 (10–60 nm) formed with free-space lengths of 53–105 nm (increasing with pH or SiO2 content), exhibiting both mass and surface-fractal structures. Reducing the amount of coupling agent resulted in an increase in the cluster size (~110 nm) and the free-space length (205 nm). At room temperature, nanocomposites prepared at pH 7 exhibited up to a 4% increase in the real relative permittivity with increasing SiO2 content, whereas those prepared at pH 11 showed up to a 5% decrease with increasing SiO2 content. Above the glass transition, all the materials exhibited low-frequency dispersion effect resulting in electrode polarization, which was amplified in the nanocomposites. Improvements in the dielectric properties were found to be not only dependent on the state of dispersion, but also the structure and morphology of the inorganic nanoparticles

The Structure, Morphology, and Complex Permittivity of Epoxy Nanodielectrics with in Situ Synthesized Surface-Functionalized SiO2

Epoxy nanocomposites have demonstrated promising properties for high-voltage insulation applications. An in situ approach to the synthesis of epoxy-SiO2 nanocomposites was employed, where surface-functionalized SiO2 (up to 5 wt.%) is synthesized directly in the epoxy. The dispersion of SiO2 was found to be affected by both the pH and the coupling agent used in the synthesis. Hierarchical clusters of SiO2 (10–60 nm) formed with free-space lengths of 53–105 nm (increasing with pH or SiO2 content), exhibiting both mass and surface-fractal structures. Reducing the amount of coupling agent resulted in an increase in the cluster size (~110 nm) and the free-space length (205 nm). At room temperature, nanocomposites prepared at pH 7 exhibited up to a 4% increase in the real relative permittivity with increasing SiO2 content, whereas those prepared at pH 11 showed up to a 5% decrease with increasing SiO2 content. Above the glass transition, all the materials exhibited low-frequency dispersion effect resulting in electrode polarization, which was amplified in the nanocomposites. Improvements in the dielectric properties were found to be not only dependent on the state of dispersion, but also the structure and morphology of the inorganic nanoparticles