Dissertation > Excellent graduate degree dissertation topics show

The Extrusion Molding Process and Rheological Properties of PAN/DMSO Solution

Author: GuoCongCong
Tutor: ChenHuiFang
School: Donghua University
Course: Materials Physics and Chemistry
Keywords: PAN Spinning solution Rheological properties Spinnability Extrusion
CLC: TQ340.6
Type: Master's thesis
Year: 2011
Downloads: 85
Quote: 0
Read: Download Dissertation

Abstract

Carbon fiber (CF) is a high-strength, high modulus, high temperature resistance, corrosion resistance and a series of excellent performance of the new material. As the reinforcing fiber of the advanced composite materials, it has been widely applied in various fields. Polyacrylonitrile (PAN) fibers as the earlier one of the synthetic fibers to achieve industrialization, polyacrylonitrile precursor to obtain a high-performance carbon fibers, its production process is simpler than other methods, the good mechanical properties of the product, which has become the production of carbon fibers The main raw silk. The structure and properties of the polyacrylonitrile precursor directly affect the quality of the final carbon fibers. Add high molecular weight PAN PAN / DMSO spinning solution prepared by wet and dry spinning polyacrylonitrile precursor. Study of the mechanical properties of the spinning solution of the steady-state and dynamic flow behavior as well as fibers and crystalline properties. Add rheological properties of high molecular weight PAN spinning solution spinnability and the preliminary findings of the original wire performance, mainly in the following aspects: the solution polymerization method, under the conditions of low conversion rate a first monomer concentration (AN), a second monomer concentration (IA), the polymerization temperature three parameters as the object to explore the preparation of high molecular weight polyacrylonitrile polymer process enhancements to ordinary molecular weight, high molecular weight polyacrylonitrile polyacrylonitrile spinning raw silk performance-based research. The reaction conditions to obtain the highest conversion rate is: AN monomer concentration of 45%, the second monomer IA concentrations of 0, and the polymerization reaction temperature was 70 ° C; obtain maximum viscosity average molecular weight of the reaction conditions is the monomer concentration was 40%, the first The second monomer IA concentrations of 0, and the polymerization temperature was 50 ° C. The study results show that: the spinning solution for shear thinning fluid, in a high shear rate, shear solution of the steady-state and dynamic rheological behavior of the spinning system through the cone and plate rheometer Dilute phenomenon; under low shear rates with increasing temperature, the viscosity of the solution gradually becomes low. By adding the high molecular weight PAN, the viscosity of the solution increases, the beneficial α / η appropriately reduced, thereby improving the spinnability and increasing the spinning stability; while the storage modulus G 'is slightly increased, will not affect the spinnability, but should control the addition amount in a suitable range. The increase in height of the air layer, Vim decreased linearly, to develop a high draw down, the height of the air layer should be suitable small. Prepared using dry and wet spinning of polyacrylonitrile fibers, carried out a detailed study on fiber morphology, structure and performance, the results showed that: the spinneret hole aspect ratio (L / D) and the draw down ratio increases large the extrudate swell effect gradually weakened. Are kidney-shaped the nascent fiber cross-section under dry and wet spinning process. The larger height of the air layer is conducive to orientation of the PAN macromolecules in the tensile force, but also should not be too high, the air layer when the height of 3cm to optimal conditions. The aspect ratio of the spinneret orifice is increased, the breaking strength of the fiber increases significantly. The total draw ratio is higher than 10 times, the stretching ratio was increased, the fiber strength is lowered, and the stretch multiples improve strength between 5-8 times, have a greater increase. Stretch system between 8-10 times a most appropriate draw ratio. The spinneret holes aspect ratio increases, a slight increase in the degree of crystallinity of the raw silk. Secondary boiling water draw ratio increases, the degree of crystallinity of the fiber and grain size of the fiber axis direction have been greatly improved.

Related Dissertations

CLC: > Industrial Technology > Chemical Industry > The chemical fiber industry > General issues > Production process
© 2012 www.DissertationTopic.Net Mobile