AI Article Synopsis
- Observing the curing reaction of epoxy resins is crucial for ensuring quality in fibre composite production, with electrical impedance spectra being a key monitoring method.
- Impedance spectra reveal physical changes during curing: early stages are dominated by ionic conductivity and electrode polarization, while dipole relaxation takes over later; evaluating across an entire frequency spectrum is more effective than focusing on a single frequency.
- A proposed frequency-dependent model simplifies the interpretation of complex raw spectral data, achieving a relative error of only 2.3% with five parameters, while indicating the need for changing key indicators as the curing process progresses.
Article Abstract
Observing the curing reaction of epoxy resins is a key to quality assurance in fibre composite production. The evaluation of electrical impedance spectra is an established monitoring method. Such impedance spectra contain the physical effects of dipole relaxation, ionic conduction and electrode polarisation, which shift to lower frequencies as curing progresses. In the early stage of the curing reaction, ionic conductivity and electrode polarisation dominate, and in the later stage of the curing reaction, dipole relaxation dominates. Due to the shift of the effects over several frequency decades, it makes sense to evaluate electrical impedance spectra not exclusively at one frequency but over an entire available frequency spectrum. The measured spectral raw data cannot be easily interpreted by a control algorithm and have to be mapped to simpler key indicators. For this purpose, a frequency-dependent model is proposed to address the aforementioned physical effects. With only five free parameters, measured spectra can be described with a relative error of only 2.3%. The shift of the occurring effects to lower frequencies necessitates switching the key indicator used in the progression of the cure reaction.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9958844 | PMC |
| http://dx.doi.org/10.3390/s23041825 | DOI Listing |
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