Frequency-Dependent Dielectric Analysis

Kranbuehl, David E.; Delos, S. E.; Hoff, M.; Weller, L.; Haverty, P.; Seeley, J.

doi:10.1021/bk-1988-0367.ch008

Cited by 10 publications

(5 citation statements)

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“…be used to determine characteristic dipolar relaxation times (1,2). Figure 1 shows the value of t " is dominated by ionic contributions throughout the first hold and at the low frequencies of the second hold.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 1 shows the value of t " is dominated by ionic contributions throughout the first hold and at the low frequencies of the second hold. These low frequency values of t " monitor the ionic mobility and thus reciprocally monitor changes in viscosity (2,7). Figure 1 shows the resin goes through an ionic mobility maximum, a viscosity minimum, at the beginning of the first and second holds at 80°C and 121°C.…”

Section: Resultsmentioning

confidence: 99%

“…Frequency dependent electromagnetic measurements (FDEMS) (1)(2)(3)(4)(5) were made with a Dek Dyne sensor-multiplexed instrument package which is available through Polymer Laboratories Inc., Amherst, Massachusetts. (Inquiries regarding the FDEMS Sensor and instrumentation should be directed to D.…”

Section: Methodsmentioning

confidence: 99%

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In‐situ monitoring of the resin transfer molding impregnation and cure process

Kranbuehl

Eichinger

Hamilton

et al. 1991

Polymer Engineering & Sci

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Resin transfer molding (RTM) of advanced fiber architecture materials promises to be a cost effective process for obtaining composite parts with exceptional strength. However there are a larger number of material processing parameters that must be observed, known, and/or controlled during the resin transfer molding process. These include the viscosity both during impregnation and cure. In-situ sensors which can observe these processing properties within the RTM tool during the fabrication process are essential. This paper will discuss recent work on the use of frequency dependent electromagnetic sensing (FDMS) techniques to monitor these properties in the RTM tool. Our objective is to use these sensing techniques to address problems of RTM scaleup for large complex parts and to develop a closed loop, intelligent, sensor controlled RTM fabrication process.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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In‐situ monitoring of the resin transfer molding impregnation and cure process

Kranbuehl

Eichinger

Hamilton

et al. 1991

Polymer Engineering & Sci

Self Cite

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“…Among the very first works devoted to use the information given by in-situ sensors (placed on or embedded in laminates) in order to set up a closed-loop control of hot-press or autoclave, one can notice the research made by Day [4] with dielectric sensors and the advances settled in the mid-eighties by Kranbuehl [5] owing electromagnetic sensors with the same purpose. Dielectric property measurements are sensitive to ionic mobility and dipolar relaxation; the obtained electrical properties are DC and AC conductivity, dielectric permittivity, and dielectric loss.…”

Section: A Brief State Of Art: Smart Composites With Embedded Sensorsmentioning

confidence: 99%

Carbon fibres reinforced composites. Electrical impedance analysis: a gateway to smartness

Marguerès

Olivier

Mounkaila

et al. 2020

International Journal of Smart and Nano Materials

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For more than 7 years, our research work is focussed upon the electrical behavior of carbon fiber reinforced composites. Effectively carbon/polymeric matrix laminates can be considered as an electrically conductive network (i.e. carbon fibers) embedded in an insulating medium (i.e. the polymeric matrix). Consequently, from an electrical point of view laminated composites have been modelled owing to combinations of electrical resistances (i.e. fibers themselves and the contact points between the fibers) and capacitances (i.e. polymeric matrix). During their manufacturing, composite material such as thermoset matrix composites for instance, undergo various changes in their physical (including electrical and mechanical) properties and in their geometrical characteristics. In fact, in the case of manufacturing processes such as oven curing (vacuum bag), autoclave curing or heating plate press, beside the chemo-rheological changes, the laminated parts are the place of a compaction phenomenon inducing changes in fiber volume fraction and thicknesses. The idea developed in this paper is that since the carbon/ polymeric matrix laminate can be considered as an electrical network, it can then be view and used as a sensor for following the material state during the manufacturing process enabling thus defects to be detected and this without any additional sensing material or device.

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“…The changes in dielectric properties are most commonly reported in terms of real (permittivity) and imaginary (loss) components of complex dielectric constant (e.g., Ref. 12,13), although the use of impedance for this purpose offers certain advantages. For instance, impedance provides an easier interpretation of results by clearly separating the contributions of electrode blocking layers, migrating charges, and dipoles; it yields a unique frequency value from which conductivity can be calculated; and it is conducive to the development of models based on equivalent circuitry.…”

Section: Introductionmentioning

confidence: 99%

Impedance Spectroscopy of Reactive Polymers: Correlations with Chemorheology during Network Formation

Mijović

Bellucci

Nicolais

1995

J. Electrochem. Soc.

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An investigation was carried out of correlations between dielectric, spectroscopic, and rheological properties during reactions in several epoxy/amine formulations of both polymer‐forming and nonpolymer‐forming nature. Dielectric results obtained from impedance spectroscopy were compared with results from near‐infrared spectroscopy, high performance liquid chromatography, and steady shear and dynamic mechanical measurements. Reaction kinetics obtained from dielectric, spectroscopic, and chromatographic results were in excellent agreement. Gelation and vitrification times of multifunctional formulations, determined by dielectric and rheological measurements, agreed surprisingly well, despite the empirical nature of such correlations. Nonetheless, a realization of the full potential of dielectric impedance spectroscopy in monitoring the progress of chemophysical changes in reactive polymers necessitates the development of fundamental scientific correlations between dielectric and chemorheological phenomena during cure.

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Frequency-Dependent Dielectric Analysis

Cited by 10 publications

References 0 publications

In‐situ monitoring of the resin transfer molding impregnation and cure process

In‐situ monitoring of the resin transfer molding impregnation and cure process

Carbon fibres reinforced composites. Electrical impedance analysis: a gateway to smartness

Impedance Spectroscopy of Reactive Polymers: Correlations with Chemorheology during Network Formation

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