Loss modulus measurement of a viscoelastic polymer at acoustic and ultrasonic frequencies using vibrothermography. (15th January 2021)

• Record Type: Journal Article
• Authors: Vaddi, Jyani S.; Holland, Stephen D.; Kessler, Michael R.
• Is Part Of: Measurement. Volume 168(2021)
• Publication Date: 2021-01-15
• Subjects: Polymer adhesive -- Loss modulus -- Vibrothermography -- Dynamic mechanical analysis -- Heat transfer; Weights and measures -- Periodicals; Measurement -- Periodicals; Measurement; Weights and measures; Periodicals; 530.8
• DOI: 10.1016/j.measurement.2020.108311
• Languages: English
• ISSNs: 0263-2241

Abstract

Abstract: This paper describes a method to calculate the loss modulus of a viscoelastic polymer material at high frequencies based on vibrothermography. The polymer material is coated on the surface of a metallic substrate and resonant mechanical vibrations are generated in the substrate. The vibrating polymer coating undergoes hysteretic heating because of its viscoelastic nature. By measuring the surface temperature of the polymer coating and by solving the heat transfer equation, the heat intensity dissipated at the polymer is estimated. The loss modulus is then calculated from the estimated heat intensity and the measured dynamic vibrational strain on the coating surface. The measurement method is demonstrated with two different polymer materials at several frequencies in the range of 12–30 kHz and these values are compared with results from dynamic mechanical analysis experiments. Highlights: Polymer materials are absorptive and dissipate heat when subjected to vibration. Loss modulus can be calculated from vibrational dynamic strain and dissipated heat. Demonstrates that loss modulus of polymer can be estimated using vibrothermography. The estimated values are comparable to dynamic mechanical analysis results.