The Formation Mechanism Of Nascent PAN Hollow Fiber Prepared By Wet-Spinning Process

The polyacrylonitrile(PAN) hollow fibers were spun by the wet spinning techologies with the C-type spinneret.And the mechanism of the PAN-based hollow fibers was studied.Forming mechanism, is divided into following four sections:First, the preparation of PAN-based hollow fiber by the wet spinning techologies was introduced. Second, the mechanism of the PAN-based hollow fiber spinning solution into a hole by the die-swell. Third, solidification surface film of PAN-based hollow fiber spinning solution during the coagulation process, including the study of surface film of PAN-based hollow fiber spinning solution mechanism. Fourth, the mechanism of coagulation regulator on polyacrylonitrile (PAN)-based hollow fiber forming the theoretical research, which includes the study of the regulator in the coagulation system. Rheological experiments of polyacrylonitrile (PAN) hollow fiber-based solution can used to analyzed its viscoelastic. Innovative cited die-swell ratio of C-type spinneret die-swell to descript the properties of spinning solution; By turbidity titration experiment, We had successfully simulated the phase separation process, and draw the PAN-DMSO-H2O ternary phase diagram. It is important to study the surface film of spinning solution during the coagulation process. The role of regulator in the mechanism of the solidification process was explored by UV spectrophotometry. Through the optical microscope observed the hollow fiber forming could verify the correctness of the mechanism.The results of rheological experiments of spinning solution show that, with the increase of shear rate, there will be viscoelastic transition point (storage modulus G' and loss modulus G" of the intersection). The emergence of viscoelastic transition point is marked the first Normal stress beginning to increase with growth of shear rate.Extended the phase separation means to delay the phase separation process was found, making the phase separation more difficult. Spinning solution system into the coagulation system, the mechanism of phase separation is the non-solvent H2O exist,which resulted to occurred association reaction with solvent DMSO. And the solvent of spinning solution was removed in the coagulation bath.So that the surface film was generated. Adding regulator in PAN-DMSO-H2O three-phase system is benefit for Slowing down the phase separation process. And than it can effectively reduce speed of the surface film formation of hollow fiber.In a word, Using C-shaped spinneret for die-swell and forming of the spinning solution during the wet spinning process in this paper. Die swell and viscoelastic of the spinning solution with different shear rate was studied. The relationship between Means of phase separation among the polymer, solvent, non-solvent and the rate of formation of thin films on fiber surface was elaborated in the coagulation bath. Revealed the formation mechanism of PAN hollow fiber structure during wet spinning process.