Reverse Flow Method Research Articles

Flow Rate Dependence of Separation and Broadening Effects in GPC

Abstract The primary objective of this work is an investigation of the separation and zone brodening effect in columns packed with porous and nonporous materials, and estimation of the accuracy of the broadening parameter, h, obtained by a reverse flow method. In order to study the separation and dispersion phenomenon in the mobile phase, and that caused by a mass-transfer process, columns packed with smooth glass beads and porous silica columns were used.

Investigation of the size distribution of non-ionic micelles formed from a polystyrene–polyisoprene block copolymer in N,N-dimethylacetamide

Solutions of a polystyrene–polyisoprene block copolymer in N,N-dimethylacetamide were studied by gel permeation chromatography. The effect of temperature on the equilibrium between free copolymer chains and micelles was studied qualitatively from 26 to 110°C. Micelles studied in detail at T= 26°C were monodisperse in size, as judged by the reverse flow method. This result was supported by electron microscopy of micelles isolated from solution. Comparison with light scattering results showed that the universal calibration method of calibration was not applicable to the micelles.The application of gel permeation chromatography in a relatively bad solvent to the analysis of a mixture of a block copolymer with a component homopolymer was demonstrated.

Uniform second-order solution for supersonic flow over delta wing using reverse-flow integral method

Abstract : The problem of supersonic flow over an inclined flatplate delta wing with supersonic edges is solved to second order in incidence. This solution for surface pressure is uniform and fully analytic. The approach utilizes a reverse-flow integral method previously developed for secondorder problems. This method is augmented by a number of techniques appropriate to its framework. The simplification over standard techniques acgieved by using these reverse-flow methods is quite substantial and makes the problem tractible. Reverse-flow procedures give a volume-surface integral relation that connects the second-order forward flow over the body of interest with the linearized reverse-flow over a related body. A singular integral equation is generated from the integral relation by introducing the edge sweep of the reverse-flow wing as a free parameter. An inversion is available which gives the second-order solution on the surface of the wing. The solution is then made uniformly valid using techniques previously developed. (Author)