Rheology of Star-Branched Polyisobutylene

• Published in: Macromolecules Vol. 32; no. 6; pp. 1972 - 1977
• Main Authors: Santangelo, P. G, Roland, C. M, Puskas, J. E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 23.03.1999
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Rheology and viscoelasticity; Isobutene polymer; Molten state; Shear modulus; Linear polymer; Molecular weight viscosity relationship; Star polymer; Experimental study; Comparative study; Rheological properties
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma9815556

The rheology of high molecular weight, six-arm-star polyisobutylenes (PIB) was measured and compared to the behavior of linear PIB. The polymers had equivalent plateau moduli and conformed well in the terminal zone to the time−temperature superposition principle. Moreover, the temperature coefficients of the terminal relaxation times were identical for the star and linear polymers. Since the trans and gauche conformations in PIB have virtually the same energy, this absence of enhanced temperature sensitivity in star PIB, as well as the thermorheological simplicity, is consistent with an interpretation of the rheology of branched polymers based on an arm retraction mechanism.