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Christophe Daniel Ian W. Hamley Manfred Wilhelm Withawat Mingvanish 《Rheologica Acta》2001,40(1):39-48
The viscoelastic behaviour of a poly(oxyethylene)-poly(oxybutylene) diblock copolymer in aqueous solution forming a face-centred
cubic (fcc) micellar phase has been investigated using oscillatory shear rheometry. With increasing strain amplitude, the
micellar solution was observed to undergo a transition from linear to non-linear behaviour, characterized by strong shear
thinning. The non-linear behaviour observed in the stress response was analyzed by Fourier transformation of the waveform.
Fourier analysis revealed that the high harmonic contributions to the shear stress response increased with strain amplitude
and up to the 81st harmonic was observed for very large amplitudes. The onset of non-linear response as defined from the dependence
of isochronal dynamic shear moduli on strain amplitude was found to be in good agreement with that defined by the appearance
of a higher harmonic in the stress waveform. The amplitudes of the harmonic coefficients are compared to the predictions of
a model for the nonlinear rheological response of a lyotropic cubic mesophase based on the stress response to a periodic lattice
potential (Jones and McLeish 1995). It is found that the model is able to account for qualitative trends in the data such
as the development of finite higher harmonics with increasing strain, but it does not describe the full frequency and strain
dependence of these coefficients.
Received: 31 May 2000 Accepted: 21 August 2000 相似文献
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This work presents a multilayer interference filter, suitable for operation with terahertz waves (T-rays). An analysis of the effect of the number of layers on the spectral response is given, with full measurement data including time-resolved signals, transmittances, and phase spectra. The silicon-air structure with a submillimeter thickness shows a stop-band between 0.2 and 0.5 THz, and the attenuation inside the stop-band increases in proportion to the number of layers in the structure. The measurement of the fabricated structure is in agreement with a characteristic matrix analysis. 相似文献
3.
Chiriaphon Chaibundit Withawat Mingvanish Simon C. Turner Shao‐Min Mai J. Patrick A. Fairclough Anthony J. Ryan Mark W. Matsen Colin Booth 《Macromolecular rapid communications》2000,21(14):964-967
EBE and BEB triblock copolymers were prepared and characterized. Microphase separation in the melt state was studied, and the results combined with those for EB and BEB copolymers reported previously. The microphase separation temperature (MST) was determined from the temperature dependence of SAXS. There was a large difference in MST between the diblock and triblock copolymers as expected from theory. The Flory‐Huggins parameter (χ) was independent of block architecture for all three series provided that the E block lengths in the EBE copolymers exceeded 65. 相似文献
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