Phase transformations during the cure of unsaturated polyester resins

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 370; no. 1; pp. 284 - 287
• Main Authors: Lionetto, F., Rizzo, R., Luprano, V.A.M., Maffezzoli, A.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.2004; Elsevier
• Subjects: Applied sciences; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Cross-disciplinary physics: materials science; rheology; Cure monitoring; Exact sciences and technology; Materials science; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase transformation; Physics; Ultrasonic analysis; Unsaturated polyester resins; Phase transformation; Unsaturated polyester resins; Ultrasonic analysis; Cure monitoring; Glass transition; Differential scanning calorimetry; Wave propagation; Rheology; Acoustical wave attenuation; Irreversible process; Ultrasound; Sound velocity
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2003.07.025

The phase transformations occurring during the cure of an unsaturated polyester resin have been investigated by different techniques, including high frequency dynamic–mechanical analysis by ultrasonic wave propagation. The increase of longitudinal sound velocity can be attributed to the increase of longitudinal modulus L′ while irreversible viscous losses are responsible for the increase of sound attenuation. A correspondence between the changes in the velocity and attenuation and the phase transformations (gelation and vitrification) can be observed. The ultrasonic properties have been compared with the gel time values obtained from parallel-plate rheological measurements. Finally, a DSC analysis has been carried out to compare the evolution of degree of reaction with that of the ultrasonic modulus.