Dissertation > Excellent graduate degree dissertation topics show

Crystallization Behavior of Electrospun Poly (L-Lactic) Nanofibers

Author: XiaoBing
Tutor: SuiGang
School: Beijing University of Chemical Technology
Course: Materials Science and Engineering
Keywords: Electrospinning Nanofibers Polylactic acid Crystallinity In situ infrared spectroscopy
CLC: TQ340.6
Type: Master's thesis
Year: 2011
Downloads: 45
Quote: 1
Read: Download Dissertation

Abstract


The electrostatic spinning the best method for the preparation of nano-scale microfiber nanofibers obtained with good continuity and uniform diameter, is widely used in the field of tissue engineering, protective materials and environmental protection engineering. However, due to the rapid evaporation of the draft effect of the high-voltage field force in the electrostatic spinning process and a solvent, so that the electro-spun fibers in the state of aggregation of the molecular chains form a unique structure, the electrospun fibers of the internal molecular chain conformation and crystallization properties electrospinning research in the field has become a hot spot. L-polylactic acid (PLLA) having a degree of crystallinity of the biodegradable polymer, there are many reports of research on the the PLLA material itself crystalline nature, but for the arrangement of the polymer chains caused by the electrostatic spinning process crystallization, especially the electrospun fiber internal molecular chain conformation changes, lack of systematic research. This experiment prepared semi-crystalline polymer PLLA nanofibers using electrospinning method, by means of XRD, DSC, and FTIR analysis of the crystalline characteristics, and pioneered the use of in situ infrared spectroscopy PLLA nanofibers crystalline molecular chain conformation changes in the process. The study found that the the PLLA nanofibers prepared by the electrostatic spinning method, due to the draft effect of the high voltage electric field force and the rapid evaporation of the solvent process, can not be formed having a crystal structure of 10/3 helical conformation. The receive mode of the fibers will affect the arrangement of the internal molecular chain of the PLLA fiber, the high speed of rotation of rollers on the nanofiber drafting further orientation of the molecular chains can be formed of a more ordered structure, resulting in the degree of crystallinity of the nanofiber improve. PLLA nanofibers, the orderly degree with the molecular size of the molecular chain, the higher the molecular weight, molecular chain entanglement effect is stronger, and its degree of ordering lower. , Adjusting the concentration range of the spinnability of the spinning solution concentration can affect the behavior of the PLLA molecular chain rearrangement and crystallization of the molecules. In the crystallization process, PLLA electrospun fiber membrane and the solution was cast molecular chains during movement of the film are different. In the cast film, the molecular chain of first-CH3 group movement, then a synergistic vibration of the COC and-CH3; electrospun fibers, it is the first occurrence of the joint action of the COC and-CH3, and-CH3 group of the independence movement. This shows that they have different crystallization mechanism. Crystalline inducer - carbon nanotubes (CNTs) added impact of of PLLA electrospun fiber crystallization experiment preliminary investigation, unlike PLLA solution casting film induced by the crystallization of CNTs in electrospun fibers, CNTs added did not play a significant induction effect, a direct result of its degree of crystallinity reduces.

Related Dissertations

  1. The Preparation and Research of Magnetically Separable TiO2 Photocatalyst Nanofibers,TB383.1
  2. The Study of Preparation and Photocatalytic Activity of TiO2 by Electrospinning,O614.411
  3. Preparation and Characterization of the OCS/PLLA Composite Film for Biomedical Materials,R318.08
  4. Preparation and Characterization of Polymer Micro/Nano Fibers by Laser Melt Electrospinning,TQ340.64
  5. Studies on the Preparation and Nutrient Release Characteristics of Low Molecular Weight Polylactic Acid Coated Urea,S145.6
  6. Establishment of Kidney-yang Deficiency Mouse Model by Inhibition of Glucocorticoid Receptor Expression,R-332
  7. Bevacizumab -PLGA Microspheres intravitreal injection in rabbit eyes pharmacokinetics and distribution of drugs,R96
  8. Inorganic filler of the modified polylactic acid,TQ320.1
  9. Inorganic and inorganic - organic hybrid Zn -based catalysts and catalytic L- lactide ring-opening polymerization of L- polylactic acid applied research,O631.3
  10. Intravitreal injection of bevacizumab PLGA Microspheres Synthesis and identification of,R943
  11. PVA / Polystyrene Composite Nanofibers Preparation and Characterization,TQ340.1
  12. Fabrication of Biomimetic Tubular Vascular Scaffold and Inducing VSMCs Alignment,R318.08
  13. Preparation of Composite Nanofibers Via Elecrtrospinng,TB383.1
  14. Effects of the High Viscosity Solution and Conductive Particles on Bubble-Electrospinning,TQ340.6
  15. Fabrication of Silk Fibroin Nanofibers Loaded with Vitamin A and E by Green Electrospinning and Evaluative Study on Its Biocompatibility,TQ340.64
  16. Research on the Resistance of PLA Fiber to Wet-hot, Dry-hot, Acid and Alkali,TQ342
  17. Preparation and Characterization of Aligned Ultrafine Fibers by Stable Jet Electrospinning,TQ340.64
  18. Numerical Simulation Study on the Process of Electrospinning and Experimental Verification,TQ340.6
  19. The Study on Controllable Preparation and Performance of Polyurethane Nano-fiber/net,TB383.1
  20. Fabric Development and Performance Analysis of PLA Fiber,TS106
  21. Studies on the Preparation and Properties of ACF/PLGA Scaffolds for Bone Tissue Engineering,R318.08

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