The melt viscosity of branched polydisperse polymers

✍ Scribed by T.W. Bates

• Publisher: Elsevier Science
• Year: 1972
• Tongue: English
• Weight: 828 KB
• Volume: 8
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(72)90079-1

✦ Synopsis

The melt viscosity (,Ta) is calculated for polydisperse branched polymers by two methods:

(1) by extending Graessley's theory of melt flow of polydisperse linear chains to include the effects of branching, and (2) by empirical deduction leading to the relation (~TB;'/('/L)= [(Ss:)w/ (SL2)~,] w2 for entangled chains. The latter method provides better agreement with experimental data on styrene/divinyl benzene copolymers and with some earlier experimental results of Charlesby on branched polydimethylsiloxanes. A theoretical comparison is also made of the melt viscosity of randomly branched polymers, homogeneous and heterogeneous in molecular weight, and of branched polymers conforming to two different distribution functions (those of Stockmayer and Beasley). Intrinsic viscosity-melt viscosity relationships for polydisperse branched polymers are also discussed.

* This approximation is justified to some extent by the calculations of Nagasubramanian et al. (18)

who found that integrals similar to that in Eqn. (7) but with exponents of 1/2 rather than 5/2 were not sensitive to the averaging procedure used for gl/2(x).