Showing papers by "Guy C. Berry published in 1990"
TL;DR: In this paper, a model involving relaxation effects giving rise to a q-independent exponential component, and one that depends on q 2, was proposed. But the model was not applied to the case of polystyrene.
18 citations
TL;DR: In this paper, the role of electrostatic interactions on the chain conformation and intermolecular interactions was investigated for phenyl-ether-phenylketone copolymers.
Abstract: Viscometric, static and light scattering data on several phenyl-ether-phenylketone copolymers (PEK, PEEK, PKEEK, PKEKEK) in solution in sulfuric acid are analyzed to elucidate the role of electrostatic interactions on the chain conformation and intermolecular interactions. It is concluded that although interactions do play an important part in intermolecular interactions, intramolecular excluded volume interactions are negligible, and the persistence length is not much affected by intramolecular electrostatic interactions. A larger than expected persistence length may be due to certain resonance-stabilized chain conformations
7 citations
TL;DR: In this paper, birefringence measurements of nematic solutions of the poly(p-phenylene benzobisthiazole), PBT, using interference between the ordinary and extraordinary waves created when a plane polarized wave enters the crystal, are described.
Abstract: Birefringence measurements of nematic solutions of the poly(p-phenylene benzobisthiazole), PBT, using interference between the ordinary and extraordinary waves created when a plane polarized wave enters the crystal, are described. The measured birefringence is high, e.g., ne - no varies from 0.05 to 0.09 at 633 nm for polymer concentrations 4x10-2 ≺ c ≺ 10x10-2(g/cm3). These data are discussed with the implications they have on the order parameter in these solutions.
1 citations
TL;DR: In this paper, the third-order nonlinear optical properties of lyotropic liquid crystal poly(1,4-phenylene-2,6-benzobisthiazole), PBT, solutions are studied by third harmonic generation measurements.
Abstract: Third-order nonlinear optical properties of lyotropic liquid crystal poly(1,4-phenylene-2,6-benzobisthiazole), PBT, solutions are studied by third harmonic generation measurements. Besides the enhancement observed for this coefficient with respect to the pure PBT, coupling is observed between the mean filed nematic director n and the incident fundamental polarization {vnE0}. Different geometries, with respect to the relative orientation of {vnE0} and n, provided different harmonic Maker Fringe Patterns. These data are compared using refractive index measurements, independently achieved on these materials, and necessary for Maker Fringe analysis.