Evolution of the Dynamics in 1,4-Polyisoprene from a Nearly Constant Loss to a Johari−Goldstein β-Relaxation to the α-Relaxation

• Published in: Macromolecules Vol. 37; no. 7; pp. 2630 - 2635
• Main Authors: Roland, C. M, Schroeder, M. J, Fontanella, J. J, Ngai, K. L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 06.04.2004
• Subjects: Applied sciences; Electrical, magnetic and optical properties; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Experimental study; Beta relaxation; Isoprene polymer; Dielectric relaxation; Cis stereoisomer

The Johari−Goldstein (JG) secondary relaxation, presumed to be universal, has never been seen in 1,4-polyisoprene (PI) by dielectric spectroscopy, despite very many measurements extending over the past half-century. By using a high-resolution capacitance bridge, we are able to show the existence of...