Affiliations 

  • 1 Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
  • 2 Section of Polymer Engineering Technology, Universiti Kuala Lumpur, Branch Campus Malaysian Institute of Chemical and Bioengineering Technology (UniKL MICET), Lot 1988, Taboh Naning, 78000 Alor Gajah, Malacca, Malaysia
R Soc Open Sci, 2019 Nov;6(11):190869.
PMID: 31827835 DOI: 10.1098/rsos.190869

Abstract

Hyperbranched polyisoprene was prepared by anionic copolymerization under high vacuum condition. Size exclusion chromatography was used to characterize the molecular weight and branching nature of these polymers. The characterization by differential scanning calorimetry and melt rheology indicated lower Tg and complex viscosity in the branched polymers as compared with the linear polymer. Degradation kinetics of these polymers was explored using thermogravimetric analysis via non-isothermal techniques. The polymers were heated under nitrogen from ambient temperature to 600°C using heating rates from 2 to 15°C min-1. Three kinetics methods namely Friedman, Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose were used to evaluate the dependence of activation energy (Ea ) on conversion (α). The hyperbranched polyisoprene decomposed via multistep mechanism as manifested by the nonlinear relationship between α and Ea while the linear polymer exhibited a decline in Ea at higher conversions. The average Ea values range from 258 to 330 kJ mol-1 for the linear, and from 260 to 320 kJ mol-1 for the branched polymers. The thermal degradation of the polymers studied involved one-dimensional diffusion mechanism as determined by Coats-Redfern method. This study may help in understanding the effect of branching on the rheological and decomposition kinetics of polyisoprene.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.