Accession Number : ADA138858

Title :   High Pressure Melting and Crystallization of Nylon-11.

Descriptive Note : Interim technical rept.,


Personal Author(s) : Chen,P K K ; Newman,B A ; Scheinbeim,J I ; Pae,K D

PDF Url : ADA138858

Report Date : 02 Mar 1984

Pagination or Media Count : 22

Abstract : Differential thermal analysis (DTA), high pressure differential thermal analysis (HP-DTA), and high temperature X-ray studies are combined to elucidate the origin of the two melting peaks in Nylon 11. The results of the studies suggest that two species of crystals are involved in the melting of Nylon 11 samples, crystallized at atmospheric pressure, when the environmental pressure is below 4 Kbars. At atmospheric pressure, the high melting species is predominant. However, under hydrostatic pressures, the high melting species undergoes phase transition to the low melting species before melting. The amount of the material involved in the transition depends on the pressure. At pressure of 4 Kbar or greater, the entire high melting species transforms to the low melting species. The melting behavior, at atmospheric pressure, of samples crystallized at high pressures also show two melting peaks if the crystallization pressure is below 4 Kbars. The amount of the low melting species increases with increasing pressure and, at 4 Kbars or higher, only melting of the low melting species is observed. The X-ray photographs taken at room temperature suggest that samples crystallized between atmospheric pressure and 3 Kbars contain both the alpha-form and the delta-form crystals but the samples crystallized at 4 Kbar and higher contain only the alpha-form crystal. However, it appears from X-ray scans taken at high temperature near melting that the low melting species is of the delta-form and the high melting species of the delta-form crystals for samples crystallized below 4 Kbars.

Descriptors :   *Nylon, *Melting, *Crystallization, Crystals, Barometric pressure, High pressure, Endothermic reactions, High temperature, Crystal structure, Hydrostatic pressure, Phase transformations, Differential thermal analysis, X ray photography

Subject Categories : Textiles

Distribution Statement : APPROVED FOR PUBLIC RELEASE