Viscoelastic behavior of polybutadienes with high 1,4-microstructure and narrow molecular weight distribution

✍ Scribed by L. He; R. Ding; A. I. Leonov; H. Dixon; R. P. Quirk

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 246 KB
• Volume: 71
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19990222)71:8<1315::aid-app11>3.0.co;2-l

✦ Synopsis

Polybutadienes (PBs) of narrow molecular weight distributions with high 1,4-microstructure were synthesized by sec-butyllithium-initiated, living polymerization. The shoulder-like anomalous behavior of the storage modulus GЈ() in the terminal zone for PBs was studied using size exclusion chromatography (SEC) and rheometric mechanical spectrometry (RMS). It was found that a high-molecular-weight fraction in the PBs was the main reason for the occurrence of the shoulders. The linear viscoelastic spectra were successfully obtained by the Pade-Laplace method from experimental dynamic data, using either the dynamic storage, GЈ(), or loss, GЉ(), modulus. Both the dynamic moduli and stress relaxation in the linear regime were then calculated with reasonable precision. The feasibility of time-temperature-molecular weight superposition for PBs using this method was demonstrated. The dependencies of relaxation spectra on temperature and molecular weight were obtained by a fitting procedure. Thus, with a known reference state, the relaxation spectrum for a given molecular weight PB at a given temperature can be predicted. The predicted dynamic moduli are in good agreement with experimental data.