Some crystallisation phenomena in rapidly quenched 6.6 nylon

Abstract

Abstract In a study of the technology of the melt spinning of 6.6 nylon filaments of diameter in the range 30–100 μ, some new crystallisation phenomena have been noted. Because of the geometrical form of the filaments, cooling from the melt is extremely rapid. Solidification takes place in a fraction of a second, and further cooling to room temperature is also rapid. The polymer can be observed at various stages during its quenching, either by taking samples from the running filaments, or by examining it whilst it is running. Under these conditions, the solid polymer is seen to have a structure not very different from that of the melt. This structure is stable at room temperature for long periods in the absence of moisture. However, on exposure to moisture, diffusion of water into the filament may result in elongation with accompanying changes in the crystalline character. The effects of temperature and moisture concentration on the diffusion process have been studied. X ‐Ray diffraction, depolarisation of light and microscopical techniques have been used to examine the crystallisation process in the filament as it is being spun and during the subsequent process of equilibration with water. X ‐Ray and optical results show changes of structure to occur on different time scales: the implications of this on the concepts of polymer morphology are discussed. The important röle played by atmospheric moisture in the crystallisation of 6.6 nylon is established, and the likely dependence on water content of second‐order transition data is examined.