Conducting polymer coated fabrics for potential applications in microwave frequencies : a study of electromagnetic properties

The microwave reflection, transmission and complex permittivity of paratoluene-2-sulfonic acid doped conducting polypyrrole (PPy/pTSA) coated Nylon-Lycra textiles in the 1-18 GHz frequency were investigated. The real part of permittivity increased with polymerization time and dopant concentration, reaching a plateau at certain dopant concentration and polymerization time. The imaginary part of permittivity showed a frequency dependent change throughout the tested range. All the samples had higher values of absorption than reflection. The total electromagnetic shielding effectiveness exceeded 80% for the highly pTSA doped samples coated for 3 hours

Galvanic Corrosion of Aluminum/Carbon Composite Systems

Aluminum/carbon composite systems can have outstanding mechanical properties. Aluminum and carbon fiber reinforced polymer matrix composites (CFRP) are typically considered corrosion resistant when used alone, but can develop severe galvanic corrosion when in physical contact in the same component or structure. General engineering practice is to avoid contact between aluminum and CFRP in any application where moisture may be present, but it is still of great importance to understand the consequences if the two materials accidentally become in contact. There may also be applications where a low rate of galvanic corrosion is acceptable. This dissertation contributes unique experimental and numerical approaches to improve the fundamental understanding of galvanic corrosion in aluminum/carbon composite systems, with particular focus on rate limiting control mechanisms in a high-temperature low-sag bare overhead transmission line conductor utilizing a CFRP load bearing core. The improved understanding was accomplished partially by the development of a novel assessment method for the in-situ galvanic corrosion testing of bare overhead conductors of various designs. The method allows for real-time measurements of galvanic corrosion currents while retaining the original geometry of the conductors. One of the most important findings is that the galvanic corrosion is under cathodic control, which means that the total galvanic corrosion rate is determined by the exposed carbon area, and independent of the exposed aluminum area. Another important finding is that the galvanic corrosion process is under diffusion control, which means that the total galvanic corrosion rate is mainly controlled by the rate at which oxygen arrives at the carbon surface. The implication of these findings is that the geometry of the component or structure can affect the galvanic corrosion rate by orders of magnitude. The dissertation work has also included the development of a structural health monitoring method for CFRP supported overhead conductors using Time Domain Reflectometry (TDR). This comprehensive research has significantly contributed to the increased acceptance of CFRP supported bare overhead conductors in both the United States and worldwide. The knowledge gained in this study is already aiding the evaluation of existing conductor designs and the development of future ones

Multidisciplinary program for stress-related disease in primary health care

Eva Ekvall Hansson1, Eva Håkansson2, Annelie Raushed2, Anders Håkansson1 1Lund University, Department of Clinical Sciences in Malmö/General Practice, Malmö, Sweden; 2Primary Health Care Malmö, SwedenObjective: To describe a multidisciplinary program, given by an occupational therapist and a physiotherapist, for patients with stress-related disease in primary health care and to measure the effect of this program in terms of self-perceived health, degree of burnout, physical activity, symptoms, recreational activities, and psychological and physical well-being.Method: Retrospective study.Results: At measures after three months, the thirteen patients included in this study had improved in self-estimated health, measured with EuroQol-5D Visual Analogue Scale (p = 0.000), and in degree of burnout, measured with the Shirom–Melamed Burnout Questionnaire (p = 0.001). There was also a decrease in presence of headache, in physical activity and in satisfaction with leisure time, although not statistically significant. After six months, the improvements remained for all measures except physical activity. The patients were also satisfied with the program to a high degree, measured with Client Satisfaction Questionnaire (median 3.7).Conclusion: This descriptive study shows that a stress-management program, provided by a team including an occupational therapist and a physiotherapist in primary health care, is both feasible and effective in terms of self-estimated health, degree of burnout, and patient satisfaction. Keywords: stress-related health, burnout, occupational therapy, physiotherap

Electromagnetic interference shielding and radiation absorption in thin polypyrrole films

Results of permittivity measurements, electromagnetic interference shielding effectiveness, and heat generation due to microwave absorption in conducting polymer coated textiles are reported and discussed. The intrinsically conducting polymer, polypyrrole, doped with anthraquinone-2-sulfonic acid (AQSA) or para-toluene-2-sulfonic acid (pTSA) was applied on textile substrates and the resulting materials were investigated in the frequency range 1&ndash;18 GHz. The 0.54 mm thick conducting textile/polypyrrole composites absorbed up to 49.5% of the incident 30&ndash;35 W microwave radiation. A thermography station was used to monitor the temperature of these composites during the irradiation process, where absorption was confirmed via visible heat losses. Samples with lower conductivity showed larger temperature increases caused by microwave absorption compared to samples with higher conductivity. A sample with an average sheet resistivity of 150 &Omega;/sq. showed a maximum temperature increase of 5.27 &deg;C, whilst a sample with a lower resistivity (105 &Omega;/sq.) rose by 3.85 &deg;C.<br /

Conductive fabrics for heating applications

By coating textiles with electrically conductive organic polymers, we are able to produce functional, intelligent fabrics. These fabrics can be utilised in applications such as gas sensors, actuators, electromagnetic shielding, radar absorption, selected frequency filtering in indoor wireless applications, and heating applications where vital parts of the body can be heated without embedding any wiring through the fabric. Heat generation in fabrics coated with the conductive polymer polypyrrole was investigated. The fabrics were coated by chemical synthesis methods by oxidizing the pyrrole monomer in the presence of the fabric substrate. Ferric chloride was selected as the oxidizing agent and anthraquinone-2-sulfonic acid (AQSA) sodium salt monohydrate as the dopant. Conductive fabrics were characterized by resistivity measurements, scanning electron microscopy, thermal imaging, current transmission over a period of time and calculations of power density per unit area. Effects of reaction conditions on the electrical properties and heat generated are presented. Polypyrrole coated fabrics were stable and possessed high electrical conductivity. Resistivity values ranged from 100-500 ohms/square depending on the reaction parameters. When subjected to a constant voltage of 24V, the polypyrrole coated polyester-Lycra&reg; fabric doped with AQSA reached a maximum temperature of 42&deg;C and a power density per unit area of 430 W/m2 was achieved.<br /

Dielectric characterization of conducting textiles using free space transmission measurements: accuracy and methods for improvement

The dielectric behaviour of in-situ polymerized thin polypyrrole (PPy) films on synthetic textile substrates were obtained in the 1&ndash;18 GHz region using free space transmission and reflection methods. The PPy/para-toluene-2-sulphonic acid (pTSA) coated fabrics exhibited an absorption dominated total shielding effectiveness (SE) of up to &minus;7.34 dB, which corresponds to more than 80% of incident radiation. The permittivity response is significantly influenced by the changes in ambient conditions, sample size and diffraction around the sample. Mathematical diffraction removal, time-gating tools and high gain horns were utilized to improve the permittivity response. A narrow time-gate of 0.15 ns produced accurate response for frequencies above 6.7 GHz and the high gain horns further improved the response in the 7.5&ndash;18 GHz range. Errors between calculated and measured values of reflection were most commonly within 2%, indicating good accuracy of the method.<br /

Electromagnetic shielding properties of polypyrrole/polyester composites in the 1–18 GHz frequency range

The dielectric characteristics of conducting polymer-coated textiles in the frequency range 1&ndash;18 GHz were investigated using a non-contact, non-destructive free space technique. Polypyrrole coatings were applied by solution polymerization on fabric substrates using a range of concentrations of para-toluene-2-sulfonic acid (pTSA) as dopant and ferric chloride as oxidant. The conducting polymer coatings exhibited dispersive permittivity behaviour with a decrease in real and imaginary components of complex permittivity as frequency increased in the range tested. Both the permittivity and the loss factor were affected by the polymerization time of the conductive coating. It was found that the total shielding efficiency of these conductive fabrics is significant at short polymerization times and increases to values exceeding 80% with longer polymerization times. The reflection contribution to electromagnetic shielding also increases with polymerization time.<br /

Galvanic Corrosion of High-Temperature Low-Sag (HTLS) High Voltage Conductors: New Materials—New Challenges

High-Temperature Low-Sag (HTLS) high voltage overhead conductors offer higher operating temperatures, reduced resistance and less sag than conventional designs. With up to twice the current capacity for the same diameter conductor, they may help ease the power shortage in the constantly increasing electricity demand, but there might be some concerns about their corrosion resistance. These new conductors use materials relatively new to the power industry, such as advanced carbon fiber polymer matrix composites and unique metal matrix composites/nano-composites predominantly used in aerospace industries. This study has made an initial assessment of potential galvanic corrosion problems in three very different HTLS designs: ACCC (Aluminum Conductor Composite Core), ACCR (Aluminum Conductor Composite Reinforced) and ACSS (Aluminum Conductor Steel Supported). In particular the ACCC design was evaluated for its resistance to corrosion and compared to the other designs. The study concludes that all three designs can develop galvanic corrosion under certain circumstances. While the results are not sufficient to make service life predictions of any of the tested conductors, they point out the necessity of thorough corrosion testing of all new conductor designs

The effects of dye dopants on the conductivity and optical absorption properties of polypyrrole

Ten anionic compounds, including four acidic dyes, were used to dope polypyrrole powder. The effects of the dopants on density, optical absorption and conductivity of the polypyrroles were studied. The presence of the dopant in the conducting polymer matrix was verified by ATR-FTIR spectroscopy. Density function theory (DFT) simulation was used to understand the effect of the dopants on the solid structure, optical absorption and energy band structures. Anthraquinone-2-sulfonic acid-doped polypyrrole yielded the highest conductivity. The dye-doped polypyrrole showed an enhancement in its UV&ndash;vis optical absorption.<br /

Can the APO method be used for measuring soft data?: A pilot study.

Objectives. The aims were to develop auditing according to the APO (Audit Project Odense) method for measuring soft data, exemplified by a holistic view, and to test the instrument. Design. A descriptive study of the development of an APO chart and a test registration. Setting. Primary health care, Blekinge County, Sweden. Subjects. Ten general practitioners (GPs) were invited to transform categories of the concept of a holistic view obtained in an earlier study, into 30 variables on an APO registration chart. The participants chose to study different kinds of knowledge as aspects of holistic care. Main outcome measure. An APO registration chart and test of the instrument. Results. After three meetings the group had drawn up an APO registration chart supplemented with Likert scales. A pilot audit was performed. Eight doctors registered 255 consultations. In assessment of the patients' problems, factual medical knowledge was important in 83% of the cases, familiarity in 53%, and a capacity for judgement in 36%. In decision-making factual medical knowledge was used in 88% and capacity for judgement in 58%. A holistic view was necessary for the outcome in 43% and valuable in 25%. The GPs used the Likert scales in a majority of the cases. Conclusions. In this first step in developing an instrument, the results indicate that the APO method could be an alternative for studying what happens in the consultation, and the occurrence of an abstract phenomenon such as the use of different kinds of knowledge as part of a holistic view