Orientation of the diphenylene propane unit in stretched polycarbonate from two-dimensional magic-angle-spinning NMR |
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Authors: | V -D Vogt M Dettenmaier H W Spiess M Pietralla |
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Institution: | (1) Present address: Max-Planck-Institut für Polymerforschung, Mainz, FRG;(2) Experimentelle Physik, Universität Ulm, Ulm, FRG |
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Abstract: | Two-dimensional magic-angle-spinning (2D-MAS) NMR has been used to measure the orientation parameter, P2, of the diphenylene propane unit in bisphenol-A polycarbonate oriented by stretching to various extension ratios, , atT=295K andT= 403 K.P
2 is proportional to the birefringence n, with a maximum birefringence n
0= 0.189. There is some evidence that the order parameterP
2
of the DPP units with respect to the chain axis deviates from unity. n
0
is therefore expected to be different from the birefringence, n
0
, of perfectly aligned chains of polycarbonate. The experimental results obtained forP
2( ) are compared to those predicted by the aggregate model. |
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Keywords: | Bisphenol-A-polycarbonate diphenylene propaneorientation birefringence order parameter |
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