Preparation Of PEO Fibers By Melt Spinning Technology And Crystallization Behavior Under Confined Condition

In this paper, the crystallization process of polymers in a cylindrically confined volume was simulated using the Monte Carlo method. The crystallization in the given system was confined in one-dimension and two-dimensions and the new turning point, named as the primary turning point, was found. The further investigation indicates that the primary turning point is one that the entities grow from three-dimensional geometry to low-dimensional one. A model of crystallization in a confined volume was proposed. The melt spinning techniques was studied to prepare PEO fibers, and the validity of the model was verified by using PEO experiment, suggesting that the model can predict the emerging condition of the primary turning point.Isothermal crystallization process of PEO6000 fibers in a confined volume at 53.5℃was simulated in the case of instantaneous nucleation by using the Monte Carlo method. It was found that there was a transformation of the growth geometry of an entity when the radii were less than 36p.m. The data were analyzed by using the Avrami equation and the result showed that the primary turning point is an indication of a transformation of crystal growth geometry from a three-dimensional mode to a one-dimensional one.Temperature programmed were used in the melt spinning, the melting time was extended and melting temperature was beyonded 90℃, air-cooled and lower spinning speed was adopted to prepare the PEO400000 fibers, then, the surface of the fibers was studied by using the microscope, it found that the fibers were adaptive to the next experiment.The isothermal crystallization behavior and the crystalline morphology of the modified and unmodified fibers were investigated using differential scanning calorim(DSC) and hot stage polarized optical microscopy (HSPOM). It is found that that there was a transformation of the growth geometry of an entity when the radius were less than 94μm, furthermore, the results of the kinetic analysis indicate that the Avrami model is invalid for describing the isothermal crystallization of this system. It was showed that a primary turning point appeared in the Avrami plot in the very beginning of the crystallization process with the exclusion of the secondary crystallization, and the model was verified. It proved that the confined volume will change the crystal growth geometry.The non-isothermal crystallization behavior and of the surface-modified and unmodified fibers were investigated using DSC, the dates of supercooled degree (ΔTc), half-width of the crystallization peaks (D_1/2), fastest time of crystallization (tmax) and half-time of crystallization (t_1/2) were given. It showed that the crystallization of surface-modified fibers is easier than the unmodified ones, and the rate of crystallization is also faster than the unmodified ones.