Deuterium n.m.r. is used to observe the change in segmental dynamics and orientation at the crystallization temperature T c in a uniaxially stretched poly(dimethylsiloxane) (PDMS) network. Experiments are performed over a wide temperature range (235–294 K). The amorphous parts of the chains are probed via perdeuterated n-octane probe molecules dissolved in the network. 2H n.m.r. spectra change drastically within a small temperature interval of 4 K in the vicinity of T c. Above T c, the spectra reflect the uniaxial dynamics of the octane probes. In the vicinity of T c, the spectra are sensitive to the internal dynamics of the octane probe and indicate a heterogeneity in the mobility of the network chains. The isotropic lines obtained for T ⱕ T c confirm that the local constraints introduced by the external deformation disappear in the amorphous part of the sample in the presence of the crystalline phase.
Посилання на статтю:
2 H n.m.r. study of a deformed poly(dimethylsiloxane) rubber network below and above the crystallization temperature / S. Valić, P. Sotta, B. Deloche // Polymer. – 1999. – N 40. – P. 989–994.