Henryk Herman | University of Surrey (original) (raw)
Papers by Henryk Herman
Polymer International, 2000
The ability to determine the molar mass of a polymer is of fundamental importance to describe pol... more The ability to determine the molar mass of a polymer is of fundamental importance to describe polymer molecular characteristics. Conventional methods for measuring molar mass include viscometry, osmometry, light scattering and analytical gel permeation chromatography (GPC). Although high quality data can be obtained by these methods, the results can be signi®cantly affected by sample preparation, and they are often time consuming and unsuitable for real-time on-line processing. In this paper, we demonstrate the potential of determining polymer molar mass using optical spectroscopy combined with chemometric analysis. This is technically attractive because optical spectroscopy is routinely used to collect process data on-line and some re®neries routinely monitor and control blending using near-infrared (NIR) spectroscopy. A comparable development to monitor polymer molar masses on-line from systems already being used to measure density and melt index, would be of potential value to many sectors of the polymer production and processing industry. Chemometrics is a multivariate methodology that allows the information from entire spectra to be used; it can be considered as a maximal compression technique. Extracted`factors' can then be regressed against property data by using a well-characterized set of`training' samples to produce predictive regression models. We will show that simple spectroscopic methods, such as the Raman technique discussed in this paper, when coupled with chemometrics, are capable of providing molar mass and distribution information. We will illustrate this with reference to poly(dimethylsiloxane)s (PDMSs) in the liquid phase.
![Research paper thumbnail of N-(2-biphenylenyl)-4-[2′-phenylethynyl]phthalimide—new monomer synthesis, cure and thermal properties of resulting high temperature polymer](https://attachments.academia-assets.com/101239303/thumbnails/1.jpg)
](Polymer, 2002
A synthetic route is described to a new monomer, N-(2-biphenylenyl)-4-[2 0-phenylethynyl]phthalim... more A synthetic route is described to a new monomer, N-(2-biphenylenyl)-4-[2 0-phenylethynyl]phthalimide (BPP), which contains both phenylethynyl and biphenylene reactive functional groups. The monomer can be made either from N-(2-biphenylene)acetamide or 2-aminobiphenylene, by reaction with the phenylethynyl-containing anhydride. The monomer was characterised fully and the thermal cure of the material was studied by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The IR spectra showed that the phenylethynyl group reacted completely within 1 h at 370 8C. DSC showed the polymerisation exotherm of BPP centred at 379 8C, lower than two NASA-developed phenylethynyl-terminated imide (PETI) resins. In comparison with the PETI systems, the T g of cured BPP was ca. 100 8C higher, making it a candidate for possible high temperature applications.
Conference Record of the 2008 IEEE International Symposium on Electrical Insulation
Electrical insulating polymers usually incorporate inorganic fillers to achieve specific electric... more Electrical insulating polymers usually incorporate inorganic fillers to achieve specific electrical, mechanical, thermal properties and reduce cost. In this exploratory work, we have studied the thermal properties, at 40 ºC, of epoxy resin composites with different filler such as: boron nitride, alumina, diamond, silicon carbide, and silicon nitride, with particle size ranges from micro to nano. The results show that BN is the best material in enhancing the thermal conductivity of the epoxy composites despite the various fillers having comparable or higher thermal conductivities than BN. Our current model shows that large disparities in mechanical modulus-a metric for interfacial compatibility-can cause thermal contact resistance due to increased phonon scattering resulting from the large mismatch between filler particle and resin matrix. I.
International Journal of Mineral Processing, 1983
2016 IEEE International Conference on Dielectrics (ICD)
With balanced consideration of the polymer matrix chemistry, nanofiller type, loading and surface... more With balanced consideration of the polymer matrix chemistry, nanofiller type, loading and surface chemical treatment, the application of multi-variate statistical analysis (MVSA) modeling was carried out to inform structure property relationships in support of material design and optimization. Fourier transform infrared spectra and physical property measurements, including thermal and electrical properties, were performed on a number of unfilled and nanosilica-filled epoxy systems. MVSA models were constructed and the ability of molecular spectroscopy to measure the target properties demonstrated. The models produced a consistent picture of chemical group correlations with electrical properties such as space charge accumulation and electrical breakdown strength, which are consistent with recent molecular dynamics calculations of the effect of group chemistry on charge transport and trapping in polymers. Findings also suggest that it is possible to gain insights into potential interactions between the resin and nanofiller.
2018 IEEE 2nd International Conference on Dielectrics (ICD), 2018
Chemometric software tools have been used to facilitate the enhanced investigation of dielectric ... more Chemometric software tools have been used to facilitate the enhanced investigation of dielectric materials in the laboratory, in manufacture and in application. These developments have made use of spectroscopic measurements for rapid and non-destructive chemical characterization, measurement of physical properties and performance, establishing structure-property relationships, materials condition assessment and quality assurance. This enables the methods to be applied at different points along the supply chain from materials research and development, to materials supply and use in manufacture, polymer and composite formulation and testing, insulation system manufacture, and finally condition assessment in manufacture, in service and at end of life.We illustrate the applicability of these methods to dielectric liquids as well as solid cable insulation by predicting structureproperty relationships, assessing thermal ageing and, critically, quantifying materials’ condition in service to support improved asset management, with examples drawn from transformers, insulators and cables.The paper will conclude with a view of the future application of these methods in materials research, manufacturing support and distributed spatial condition assessment for improved asset management.
2018 12th International Conference on the Properties and Applications of Dielectric Materials (ICPADM), 2018
We have developed and applied chemometric software tools to facilitate the enhanced investigation... more We have developed and applied chemometric software tools to facilitate the enhanced investigation of dielectric materials in the laboratory, in manufacture and in application. These developments have in particular made use of spectroscopic measurements for rapid and non-destructive chemical characterisation, measurement of physical properties and performance, establishing structure-property relationships, materials condition assessment and quality assurance. This enables the basic methods and tools to be applied at different points in the development cycle along the supply chain from materials research and development, to materials supply and use in manufacture, polymer and composite formulation and testing, insulation system manufacture, condition assessment in manufacture, in service and at end of life. We illustrate the applicability of these methods dielectric liquids as well as solids in both thermoplastic and thermoset based insulation systems, the measurement of physical properties and structure-property relationships, the assessment of thermal ageing and critically the measurement of materials condition in service to support improved asset management, with examples drawn from transformers, insulators and cables. The paper will conclude with a view of the future application of these methods in materials research, manufacturing support and distributed spatial condition assessment for improved asset management.
ECS Meeting Abstracts, 2012
Proceedings of the 2004 IEEE International Conference on Solid Dielectrics, 2004. ICSD 2004.
Rapid in-situ analysis of the condition of power transformer winding insulation kraft paper, to p... more Rapid in-situ analysis of the condition of power transformer winding insulation kraft paper, to provide information on its aged condition, is an imperative in the power industry. The ability to achieve this with portable instrumentation would be very beneficial. The insulation paper degrades over time, and the degree of polymerisation (DP) of the paper affects its structural integrity. At low
Journal of Applied Polymer Science, 2001
ABSTRACT Bis(acetanilido)-tris(acetato)dicuprate(II), [Cu2(C7H8N2O)2(CH3CO2−)3], is incorporated ... more ABSTRACT Bis(acetanilido)-tris(acetato)dicuprate(II), [Cu2(C7H8N2O)2(CH3CO2−)3], is incorporated into MY721, a commercial epoxy resin recognised as an ‘industry standard’. Infrared spectroscopy and thermogravimetry are employed to examine the structure and thermal dissociation behaviour of the newly prepared complex. Multivariate analysis techniques (e.g. principal components analysis) are used to examine the spectral data to corroborate the dissociation temperature. The shelf life and cure characteristics of the commercial epoxy/curing agent formulation are determined using differential scanning calorimetry and vibrational spectroscopy.
Rapid, cost-effective, non-destructive diagnosis of power transformer condition is an increasingl... more Rapid, cost-effective, non-destructive diagnosis of power transformer condition is an increasingly important area of asset management – this includes the need to be able to estimate the aged condition of the coil insulation nondestructively. This is necessary to assess the reliability and potential risks presented by transformers in a particular population as well as gauging the prospective life expectancy of individual transformers. A portable fiber-optic spectroscopic probe system has been developed which can achieve this quickly by determining the degree of polymerization (DP), an indicator of degradation, to an accuracy of 40 DP units in the presence of the insulating oil. The system uses a hand-held optical probe that gathers spectral information which is analysed using dedicated multivariate analysis software. Following calibration and measurement trials in the laboratory, the instrument has been used in the field, to provide DP values based on in-situ measurements of the expo...
… , IEEE Transactions on, 2006
A portable fiber-optic spectroscopic system (TRANSPEC) has been developed for nondestructive meas... more A portable fiber-optic spectroscopic system (TRANSPEC) has been developed for nondestructive measurement of aged transformer insulating paper. Following successful measurement of degree of polymerization (DP) of a range of transformer-aged paper samples, the system has now been shown to separate the oil and paper information for measurement of DP in oil-wetted paper samples. In addition, the system has been shown to be capable of the prediction of both oil and water content of paper to a high accuracy, and is also capable of identifying and quantifying different water species. Spectroscopic measurements have been used together with gravimetric water adsorption measurements to investigate the kinetics of uptake of water vapour into paper from air in the case of nominally dry and oil-impregnated samples. Relationships between water adsorption parameters and properties of the paper insulation have also been investigated using measurements under controlled conditions.
… , IEEE Transactions on, 2006
Knowledge of the condition of power transformer winding insulation paper is fundamental to making... more Knowledge of the condition of power transformer winding insulation paper is fundamental to making optimum asset replacement decisions in the power industry. The ability to assess the aged condition of Kraft paper quickly and non-destructively using portable instrumentation would significantly increase the opportunities for gaining this knowledge. Insulation paper degrades over time in-service and its degree of polymerization (DP) reduces, eventually affecting its mechanical strength. At low DP levels the insulation may start to disintegrate and the risk of electrical breakdown increases. Currently-used methods of estimating DP are either approximate or destructive. The use of spectroscopy together with multivariate statistical analysis (MVSA) provides a powerful non-destructive evaluation of the condition of paper. From initial feasibility studies, we have developed a simple, portable system (TRANSPEC) using fiber-optics and broad-band spectroscopy that can measure the degree of polymerization of various aged transformer papers to a precision of approximately 30 DP units with a spatial resolution of 14 mm. The system can also measure the chemical composition and condition of the insulating mineral oil. MVSA regression models were constructed from library spectral data, and these models are used to predict the DP of other papers with parameters that fall within the range spanned by the set of calibration samples. Separating oil and moisture information from wetted paper is possible and will be reported in a separate publication. With a single TRANSPEC system, non-destructive in-situ analysis of the DP of insulating paper is possible, providing a rapid cost-effective method for transformer insulation condition assessment and monitoring, which correlates well with current destructive methods.
Journal of Physics E: Scientific Instruments
Journal of Physics B: Atomic and Molecular Physics
Polymer International, 2000
The ability to determine the molar mass of a polymer is of fundamental importance to describe pol... more The ability to determine the molar mass of a polymer is of fundamental importance to describe polymer molecular characteristics. Conventional methods for measuring molar mass include viscometry, osmometry, light scattering and analytical gel permeation chromatography (GPC). Although high quality data can be obtained by these methods, the results can be signi®cantly affected by sample preparation, and they are often time consuming and unsuitable for real-time on-line processing. In this paper, we demonstrate the potential of determining polymer molar mass using optical spectroscopy combined with chemometric analysis. This is technically attractive because optical spectroscopy is routinely used to collect process data on-line and some re®neries routinely monitor and control blending using near-infrared (NIR) spectroscopy. A comparable development to monitor polymer molar masses on-line from systems already being used to measure density and melt index, would be of potential value to many sectors of the polymer production and processing industry. Chemometrics is a multivariate methodology that allows the information from entire spectra to be used; it can be considered as a maximal compression technique. Extracted`factors' can then be regressed against property data by using a well-characterized set of`training' samples to produce predictive regression models. We will show that simple spectroscopic methods, such as the Raman technique discussed in this paper, when coupled with chemometrics, are capable of providing molar mass and distribution information. We will illustrate this with reference to poly(dimethylsiloxane)s (PDMSs) in the liquid phase.
Polymer, 2002
A synthetic route is described to a new monomer, N-(2-biphenylenyl)-4-[2 0-phenylethynyl]phthalim... more A synthetic route is described to a new monomer, N-(2-biphenylenyl)-4-[2 0-phenylethynyl]phthalimide (BPP), which contains both phenylethynyl and biphenylene reactive functional groups. The monomer can be made either from N-(2-biphenylene)acetamide or 2-aminobiphenylene, by reaction with the phenylethynyl-containing anhydride. The monomer was characterised fully and the thermal cure of the material was studied by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The IR spectra showed that the phenylethynyl group reacted completely within 1 h at 370 8C. DSC showed the polymerisation exotherm of BPP centred at 379 8C, lower than two NASA-developed phenylethynyl-terminated imide (PETI) resins. In comparison with the PETI systems, the T g of cured BPP was ca. 100 8C higher, making it a candidate for possible high temperature applications.
Conference Record of the 2008 IEEE International Symposium on Electrical Insulation
Electrical insulating polymers usually incorporate inorganic fillers to achieve specific electric... more Electrical insulating polymers usually incorporate inorganic fillers to achieve specific electrical, mechanical, thermal properties and reduce cost. In this exploratory work, we have studied the thermal properties, at 40 ºC, of epoxy resin composites with different filler such as: boron nitride, alumina, diamond, silicon carbide, and silicon nitride, with particle size ranges from micro to nano. The results show that BN is the best material in enhancing the thermal conductivity of the epoxy composites despite the various fillers having comparable or higher thermal conductivities than BN. Our current model shows that large disparities in mechanical modulus-a metric for interfacial compatibility-can cause thermal contact resistance due to increased phonon scattering resulting from the large mismatch between filler particle and resin matrix. I.
International Journal of Mineral Processing, 1983
2016 IEEE International Conference on Dielectrics (ICD)
With balanced consideration of the polymer matrix chemistry, nanofiller type, loading and surface... more With balanced consideration of the polymer matrix chemistry, nanofiller type, loading and surface chemical treatment, the application of multi-variate statistical analysis (MVSA) modeling was carried out to inform structure property relationships in support of material design and optimization. Fourier transform infrared spectra and physical property measurements, including thermal and electrical properties, were performed on a number of unfilled and nanosilica-filled epoxy systems. MVSA models were constructed and the ability of molecular spectroscopy to measure the target properties demonstrated. The models produced a consistent picture of chemical group correlations with electrical properties such as space charge accumulation and electrical breakdown strength, which are consistent with recent molecular dynamics calculations of the effect of group chemistry on charge transport and trapping in polymers. Findings also suggest that it is possible to gain insights into potential interactions between the resin and nanofiller.
2018 IEEE 2nd International Conference on Dielectrics (ICD), 2018
Chemometric software tools have been used to facilitate the enhanced investigation of dielectric ... more Chemometric software tools have been used to facilitate the enhanced investigation of dielectric materials in the laboratory, in manufacture and in application. These developments have made use of spectroscopic measurements for rapid and non-destructive chemical characterization, measurement of physical properties and performance, establishing structure-property relationships, materials condition assessment and quality assurance. This enables the methods to be applied at different points along the supply chain from materials research and development, to materials supply and use in manufacture, polymer and composite formulation and testing, insulation system manufacture, and finally condition assessment in manufacture, in service and at end of life.We illustrate the applicability of these methods to dielectric liquids as well as solid cable insulation by predicting structureproperty relationships, assessing thermal ageing and, critically, quantifying materials’ condition in service to support improved asset management, with examples drawn from transformers, insulators and cables.The paper will conclude with a view of the future application of these methods in materials research, manufacturing support and distributed spatial condition assessment for improved asset management.
2018 12th International Conference on the Properties and Applications of Dielectric Materials (ICPADM), 2018
We have developed and applied chemometric software tools to facilitate the enhanced investigation... more We have developed and applied chemometric software tools to facilitate the enhanced investigation of dielectric materials in the laboratory, in manufacture and in application. These developments have in particular made use of spectroscopic measurements for rapid and non-destructive chemical characterisation, measurement of physical properties and performance, establishing structure-property relationships, materials condition assessment and quality assurance. This enables the basic methods and tools to be applied at different points in the development cycle along the supply chain from materials research and development, to materials supply and use in manufacture, polymer and composite formulation and testing, insulation system manufacture, condition assessment in manufacture, in service and at end of life. We illustrate the applicability of these methods dielectric liquids as well as solids in both thermoplastic and thermoset based insulation systems, the measurement of physical properties and structure-property relationships, the assessment of thermal ageing and critically the measurement of materials condition in service to support improved asset management, with examples drawn from transformers, insulators and cables. The paper will conclude with a view of the future application of these methods in materials research, manufacturing support and distributed spatial condition assessment for improved asset management.
ECS Meeting Abstracts, 2012
Proceedings of the 2004 IEEE International Conference on Solid Dielectrics, 2004. ICSD 2004.
Rapid in-situ analysis of the condition of power transformer winding insulation kraft paper, to p... more Rapid in-situ analysis of the condition of power transformer winding insulation kraft paper, to provide information on its aged condition, is an imperative in the power industry. The ability to achieve this with portable instrumentation would be very beneficial. The insulation paper degrades over time, and the degree of polymerisation (DP) of the paper affects its structural integrity. At low
Journal of Applied Polymer Science, 2001
ABSTRACT Bis(acetanilido)-tris(acetato)dicuprate(II), [Cu2(C7H8N2O)2(CH3CO2−)3], is incorporated ... more ABSTRACT Bis(acetanilido)-tris(acetato)dicuprate(II), [Cu2(C7H8N2O)2(CH3CO2−)3], is incorporated into MY721, a commercial epoxy resin recognised as an ‘industry standard’. Infrared spectroscopy and thermogravimetry are employed to examine the structure and thermal dissociation behaviour of the newly prepared complex. Multivariate analysis techniques (e.g. principal components analysis) are used to examine the spectral data to corroborate the dissociation temperature. The shelf life and cure characteristics of the commercial epoxy/curing agent formulation are determined using differential scanning calorimetry and vibrational spectroscopy.
Rapid, cost-effective, non-destructive diagnosis of power transformer condition is an increasingl... more Rapid, cost-effective, non-destructive diagnosis of power transformer condition is an increasingly important area of asset management – this includes the need to be able to estimate the aged condition of the coil insulation nondestructively. This is necessary to assess the reliability and potential risks presented by transformers in a particular population as well as gauging the prospective life expectancy of individual transformers. A portable fiber-optic spectroscopic probe system has been developed which can achieve this quickly by determining the degree of polymerization (DP), an indicator of degradation, to an accuracy of 40 DP units in the presence of the insulating oil. The system uses a hand-held optical probe that gathers spectral information which is analysed using dedicated multivariate analysis software. Following calibration and measurement trials in the laboratory, the instrument has been used in the field, to provide DP values based on in-situ measurements of the expo...
… , IEEE Transactions on, 2006
A portable fiber-optic spectroscopic system (TRANSPEC) has been developed for nondestructive meas... more A portable fiber-optic spectroscopic system (TRANSPEC) has been developed for nondestructive measurement of aged transformer insulating paper. Following successful measurement of degree of polymerization (DP) of a range of transformer-aged paper samples, the system has now been shown to separate the oil and paper information for measurement of DP in oil-wetted paper samples. In addition, the system has been shown to be capable of the prediction of both oil and water content of paper to a high accuracy, and is also capable of identifying and quantifying different water species. Spectroscopic measurements have been used together with gravimetric water adsorption measurements to investigate the kinetics of uptake of water vapour into paper from air in the case of nominally dry and oil-impregnated samples. Relationships between water adsorption parameters and properties of the paper insulation have also been investigated using measurements under controlled conditions.
… , IEEE Transactions on, 2006
Knowledge of the condition of power transformer winding insulation paper is fundamental to making... more Knowledge of the condition of power transformer winding insulation paper is fundamental to making optimum asset replacement decisions in the power industry. The ability to assess the aged condition of Kraft paper quickly and non-destructively using portable instrumentation would significantly increase the opportunities for gaining this knowledge. Insulation paper degrades over time in-service and its degree of polymerization (DP) reduces, eventually affecting its mechanical strength. At low DP levels the insulation may start to disintegrate and the risk of electrical breakdown increases. Currently-used methods of estimating DP are either approximate or destructive. The use of spectroscopy together with multivariate statistical analysis (MVSA) provides a powerful non-destructive evaluation of the condition of paper. From initial feasibility studies, we have developed a simple, portable system (TRANSPEC) using fiber-optics and broad-band spectroscopy that can measure the degree of polymerization of various aged transformer papers to a precision of approximately 30 DP units with a spatial resolution of 14 mm. The system can also measure the chemical composition and condition of the insulating mineral oil. MVSA regression models were constructed from library spectral data, and these models are used to predict the DP of other papers with parameters that fall within the range spanned by the set of calibration samples. Separating oil and moisture information from wetted paper is possible and will be reported in a separate publication. With a single TRANSPEC system, non-destructive in-situ analysis of the DP of insulating paper is possible, providing a rapid cost-effective method for transformer insulation condition assessment and monitoring, which correlates well with current destructive methods.
Journal of Physics E: Scientific Instruments
Journal of Physics B: Atomic and Molecular Physics