Viscoelastic Properties of Poly(methyl methacrylates) Prepared by Anionic Polymerization
1970; Springer Nature; Volume: 1; Issue: 4 Linguagem: Inglês
10.1295/polymj.1.418
ISSN1349-0540
AutoresToshiro Masuda, Keishi Kitagawa, Shigeharu Onogi,
Tópico(s)Polymer Nanocomposites and Properties
ResumoThe viscoelastic properties of poly(methyl methacrylates) obtained by anionic polymerization were measured in the molten state by means of a concentric cylinder type rheometer over wide ranges of frequency and temperature. From the frequency dependence of the storage modulus G′ and the loss modulus G″, the characteristic parameters in the terminal zone, such as zero-shear viscosity η0 and steady-state compliance Je0 were evaluated, and the dependence of these parameters on the molecular weight M was discussed, η0 and Je0 for samples having molecular weights higher than the critical molecular weight MC were respectively proportional to M4.4 and M. The quasi-equiliblium modulus GeN0 and the average molecular weight between entanglement coupling loci, Me, were also evaluated. Me was found to increase gradually from 6760 to 13100 with increasing molecular weight. The ratio Mc/Me was not constant but varied from 6 to 2, being larger than the value of 2 obtained by previous authors, both theoretically and experimentally. The parameters for this material are discussed in connection with molecular structure, together with those for anionic polystyrene published in the previous paper.
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