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synopeisThree preparativeacale gel permeation chromatography columns were constructed and filled with Corning porous-glass packing materials. Each column was packed with a Merent poreaize material, CPG 10-2000, CPG 10-350, CPG 10-120, all of which had been treated with hexamethyldisiiazane. An additional preparative-scale column packed with Styragel, nominal porosity 5 X 10' A, was added to complete the column bank. Polystyrene standards were used to investigate the effects of molecular weight and sample concentration upon elution volume. A commercial polystyrene sample was fractionated using this system to study the effects of sample concentration and flow rate on fractionation efficiency. These fractions were analyzed by high-resolution analyticalscale gel permeation chromatography. Where possible, the results have been compared with similar studies that used Porasil (Spherosil) and Styragel columns.

A technique for the selective degradation of amorphous regions in nylon 6,6 is reported. Samples of unoriented film and single‐crystal mats have been subjected to selective degradation by refluxing in hydrazine. Weight loss, viscosity‐average molecular weight, density, and small‐angle x‐ray scattering of these samples were monitored as a function of time of degradation. In addition, selected samples have been investigated by gel permeation chromatography (GPC) and transmission electron microscopy. Based on the results of these investigations it is concluded that the reported degradation technique is unique in that the debris is not monodisperse in molecular weight distribution. The Weight loss, density, small‐angle x‐ray scattering, and microscopy data demonstrate that the unordered or noncrystalline regions of the material are removed upon treatement. However, the relatively high molecular weight and broad molecular weight distribution of the debris indicate that regular folds at lamellar surfaces are intact after degradation treatment.

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