Abstract
Viscometric measurements, in toluene solution at 30 oC, were performed with high-cis polybutadiene synthesized by neodymium based catalyst. Six different equations were used to calculate intrinsic viscosities and viscosimetric constant values: Huggins, Kraemer, Martin and Schulz-Blaschke by graphic extrapolation, and Solomon-Ciuta, Deb-Chanterjee and again Schulz-Blaschke, through a single point determination. The molecular weight of the polymers was also determined applying Mark-Houwink-Sakurada equation using the values of intrinsic viscosity obtained by the six equations. The values of intrinsic viscosity and viscosity-average molecular weight obtained by the two methods were compared in order to verify the validity of the single point determination for high-cis polybutadiene.
Highlights
High cis-polybutadiene (BR) is commercially obtained by solution polymerization using Ziegler-Natta catalyst systems based on titanium, cobalt or nickel and more recently on lanthanides, being neodymium-based catalysts active and stereospecific
The percentual differences obtained for intrinsic viscosity values from SB equation, by a single point determination were remarkably lower than those calculated by graphic extrapolation data
By comparing Schulz-Blaschke (SB), Solomon-Ciuta (SC) and Deb-Chanterjee (DC) equations employed in the single point determination, it is notable that intrinsic viscosity values obtained from SC equation produced the smallest percentual differences for BR-4 and BR-5
Summary
High cis-polybutadiene (BR) is commercially obtained by solution polymerization using Ziegler-Natta catalyst systems based on titanium, cobalt or nickel and more recently on lanthanides, being neodymium-based catalysts active and stereospecific. Ksb = 0.28 has been found.[6,7,10] Some relations have been proposed for determining the intrinsic viscosity from a single point viscosity measurement of a dilute solution.
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