Multiaxial deformations of end-linked poly(dimethylsiloxane) networks. 2. Experimental tests of molecular entanglement models of rubber elasticity

Citation
K. Urayama et al., Multiaxial deformations of end-linked poly(dimethylsiloxane) networks. 2. Experimental tests of molecular entanglement models of rubber elasticity, MACROMOLEC, 34(23), 2001, pp. 8261-8269
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
MACROMOLECULES
ISSN journal
0024-9297 → ACNP
Volume
34
Issue
23
Year of publication
2001
Pages
8261 - 8269
Database
ISI
SICI code
0024-9297(20011106)34:23<8261:MDOEPN>2.0.ZU;2-2
Abstract
Five molecular models of rubber elasticity which employ different treatment s of entanglement effects (the Kloczkowski-Mark-Erman diffused-constraint m odel, the Edwards-Vilgis (E-V) slip-link model, the tube models of Gaylord- Douglas (G-D), Kaliske-Heinrich, Rubinstein-Panyukov versions) are assessed using biaxial deformation data for an entanglement-dominated network of en d-linked poly(dimethylsiloxane) (PDMS) in which trapped entanglements are d ominant in number relative to chemical cross-links. The theoretical stress- strain relations were calculated from the elastic free energy (M of each mo del. Using the reduced stress (the nominal stress divided by equilibrium mo dulus G(o)), the strain-dependent predictions of each model were tested fro m two different viewpoints, i.e., the dependence of the reduced stresses on the principal ratio and the I-i dependence of (partial derivativeW/partial derivativeI(j))/G(o) (i,j = 1,2), where I-1 and I-2 are the first and seco nd invariants of deformation tensor (the Rivlin-Saunders method). The diffu sed-constraint model is relatively successful in reproducing the reduced st ress-strain data over a wide range of deformations, but the model definitel y underestimates the magnitude of G because it does not consider trapped en tanglements as additional cross-links contributing to G., in contrast to th e tube models and the slip-link models. The G-D tube model is more successf ul in reproducing the experimental data relative to the other two versions of the tube model, but the G-D model obviously underestimates the stresses at large deformations. Among the five molecular theories tested here, the E -V slip-link model shows the most successful reproducibility over large por tions of the experimental results. The agreements in reduced stress-strain relations are satisfactory over the entire deformation range, although cons iderable disagreement is recognized in the I-i dependence of partial deriva tiveW/partial derivativeI(2). Also, the fitted parameter values in the E-V slip-link model are fairly well explained using the molecular consideration s based on the structural characteristics of the network sample employed he re.