J. Phys. II France
Volume 3, Numéro 11, November 1993
Page(s) 1619 - 1631
DOI: 10.1051/jp2:1993222
J. Phys. II France 3 (1993) 1619-1631

Segmental order in uniaxially strained bimodal polymer networks: a deuterium-NMR study

B. Chapellier1, B. Deloche1 and R. Oeser2

1  Laboratoire de Physique des Solides (CNRS-LA 0002), Université Paris-Sud, 91405 Orsay, France
2  Institut Laue-Langevin (ILL), B.P. 156 X, 38042 Grenoble, France

(Received 20 April 1993, accepted in final form 12 August 1993)

The segmental orientational order generated in bimodal poly(dimethylsiloxane) networks under uniaxial stress is probed using deuterium nuclear magnetic resonance ( 2H-NMR). The induced segmental order is measured either on "short" chains ( $M_{\rm n} = 3000$ g/mol) or on "long" chains ( $M_{\rm n} = 25000$ g/mol). The segmental orientation is very similar for both kinds of chains and decreases linearly as the volume fraction $\Phi_{\rm L}$ of "long" chain increases. A mean field analysis including orientational correlations between segments is developed and accounts for these observations. Additionally, this study has been carried out on two sets of samples with different crosslinkers. It shows clearly that the induced orientational order depends on the nature of the crosslinking junctions.

61.16N - 61.40K

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