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Monitoring the Cure State of Thermosetting Resins by Ultrasound
Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce, Italy
* Author to whom correspondence should be addressed.
Received: 23 July 2013; in revised form: 20 August 2013 / Accepted: 26 August 2013 / Published: 5 September 2013
Abstract: The propagation of low intensity ultrasound in a curing resin, acting as a high frequency oscillatory excitation, has been recently proposed as an ultrasonic dynamic mechanical analysis (UDMA) for cure monitoring. The technique measures sound velocity and attenuation, which are very sensitive to changes in the viscoelastic characteristics of the curing resin, since the velocity is related to the resin storage modulus and density, while the attenuation is related to the energy dissipation and scattering in the curing resin. The paper reviews the results obtained by the authors’ research group in the last decade by means of in-house made ultrasonic set-ups for both contact and air-coupled ultrasonic experiments. The basics of the ultrasonic wave propagation in polymers and examples of measurements of the time-evolution of ultrasonic longitudinal modulus and chemical conversion of different thermosetting resins are presented. The effect of temperature on the cure kinetics, the comparison with rheological, low frequency dynamic mechanical and calorimetric results, and the correlation between ultrasonic modulus and crosslinking density will be also discussed. The paper highlights the reliability of ultrasonic wave propagation for monitoring the physical changes taking place during curing and the potential for online monitoring during polymer and polymer matrix composite processing.
Keywords: ultrasonic wave propagation; ultrasonic dynamic mechanical analysis; viscoelastic properties; cure monitoring; gelation; vitrification; longitudinal modulus; thermosetting resins
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MDPI and ACS Style
Lionetto, F.; Maffezzoli, A. Monitoring the Cure State of Thermosetting Resins by Ultrasound. Materials 2013, 6, 3783-3804.
Lionetto F, Maffezzoli A. Monitoring the Cure State of Thermosetting Resins by Ultrasound. Materials. 2013; 6(9):3783-3804.
Lionetto, Francesca; Maffezzoli, Alfonso. 2013. "Monitoring the Cure State of Thermosetting Resins by Ultrasound." Materials 6, no. 9: 3783-3804.