9 research outputs found

    ā€˜Holding on to regret as a kind of enrichmentā€™ā€“a qualitative exploration of the role that work-related regrets play in therapistsā€™ clinical practice

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    In this reflexive thematic analysis, we explore 17 psychotherapistsā€™ accounts of work-related regrets. Based on individual interviews with experienced clinical psychologists, we report how they describe these regrets as emotionally intense experiences with potential for development. To communicate how participants view work-related regrets to impact on their clinical practice, we formulated an overarching theme called ā€œholding on to regret as a kind of enrichment.ā€ Three subthemes summarize different aspects of this process: (a) increased awareness; (b) working to accept and model fallibility; and (c) the process of making changes based on regret experiences. We discuss our findings in relation to theory and research, and explore methodological strengths and limitations.publishedVersio

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

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    Epoxy nanocomposites, with inorganic oxide nanoparticles as ļ¬ller, 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 ļ¬nal properties of the nanocomposite. Here, the processing methods and the resulting dielectric, mechanical, and thermal properties of epoxy nanocomposites with inorganic oxide ļ¬llers are presented. Functionalization of the nanoparticle generally improves the dispersion of the particles in the polymer matrix. Different oxide ļ¬llers 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 ļ¬ller contents, compared to conventional composites with micrometer-sized particles. While there are some inconsistencies in the ļ¬ndings, which may be attributed to differences in the dispersion quality, an improved understanding of the nanoparticleā€“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

    In situ synthesis of epoxy nanocomposites with hierarchical surface-modiļ¬ed SiO2 clusters

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    Polymer nanocomposites are often produced using in situ approaches where an inorganic ļ¬ller (as the dispersed phase) is synthesized directly in an organic matrix. Such an approach generally leads to improved dispersion and reduced agglomeration of the ļ¬ller material. Epoxy-based nanocomposites have demonstrated promising properties for application as high-voltage insulation materials. In this work, a solā€“gel based method has been adapted to synthesize surface-functionalized SiO2 in situ in epoxy. The synthesized SiO2 moieties were dispersed in clusters of 10ā€“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 signiļ¬cant 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

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

    No full text
    Epoxy nanocomposites, with inorganic oxide nanoparticles as ļ¬ller, 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 ļ¬nal properties of the nanocomposite. Here, the processing methods and the resulting dielectric, mechanical, and thermal properties of epoxy nanocomposites with inorganic oxide ļ¬llers are presented. Functionalization of the nanoparticle generally improves the dispersion of the particles in the polymer matrix. Different oxide ļ¬llers 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 ļ¬ller contents, compared to conventional composites with micrometer-sized particles. While there are some inconsistencies in the ļ¬ndings, which may be attributed to differences in the dispersion quality, an improved understanding of the nanoparticleā€“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

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    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 (10ā€“60 nm) formed with free-space lengths of 53ā€“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

    No full text
    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 (10ā€“60 nm) formed with free-space lengths of 53ā€“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

    Theoretical and Experimental Determination of Thermomechanical Properties of Epoxy-SiO<inf>2</inf> Nanocomposites

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    Improvements in the thermomechanicalproperties of epoxy upon inclusion of well-dispersed SiO2nanoparticles have been demonstrated both experimentally and through molecular dynamics simulations.The SiO2was represented by two different dispersion models: dispersedindividual molecules and as spherical nanoparticles.The calculated thermodynamic and thermomechanical properties were consistent with experimental results. Radial distribution functions highlight the interactions of different parts of the polymer chains with the SiO2between 3 and 5 nminto the epoxy, depending on the particle size.Thefindingsfrombothmodels were verified against experimentalresultslike theglass transitiontemperatureand tensile elasticmechanicalproperties,and proved suitable for predicting thermomechanicaland physicochemical properties of epoxy-SiO2nanocompositesTheoretical and Experimental Determination of Thermomechanical Properties of Epoxy-SiO2 NanocompositespublishedVersio
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