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Post-Treatment of the Dry-Spun Fibers from Regenerated Silk Fibroin Aqueous Solution

Author: ZhaoZuoMei
Tutor: ZhangYaoPeng
School: Donghua University
Course: Materials Science
Keywords: Regenerated silk fibroin fiber Dry spinning After-treatment Orientation Structural changes Mechanical Properties
CLC: TQ340.65
Type: Master's thesis
Year: 2011
Downloads: 81
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Abstract

Spider and silkworm water as solvent, the excellent mechanical properties of natural animal wire prepared by dry spinning method in air. Although many researchers try using a wet spinning or electrostatic spinning process Biomimetic artificial animal wire, but overall spinning process is simple, low level of bionic spider and silkworm spinning method. Our group pre regenerated silk fibroin (RSF) aqueous solution spinning solution dry spinning process successfully prepared RSF fiber, but the mechanical properties of natural silk is still a big gap. In order to improve the mechanical properties of the dry spinning comparable to natural animal wire, high-performance protein fibers, the paper the dry spinning RSF protofibers were processing. Preferred non-toxic, environment-friendly and can promote 80 vo1% aqueous ethanol as RSF conformation change after treatment agent, mechanical design and development of ultra-fine monofilament stretching device using polarizing microscopy, Raman spectroscopy, infrared spectroscopy, scanning means of electron microscopy to explore the storage conditions of the spun fiber, RSF fiber single-stage stretching and multi-level after stretching process to clarify the evolution of structure in the post-processing of the RSF fiber, for the preparation of high-performance artificial bionic animal wire to provide a reference. To stabilize the mechanical properties of the RSF spun fiber, the fiber obtained after the dry-spinning should be stored at a relative humidity of 30-35% in a sealed container for at least three days. After ethanol atmosphere RSF processing can induce the formation of the ordered state structure of the p-sheet conformation, but the poor alignment structure, and mechanical properties compared with the RSF protofibers but decreased. The orientation of the β-sheet structure must be formed, can be expected to improve the mechanical properties of the fibers. In order to optimize the post-treatment process of dry spinning RSF fibers, this thesis quantitative study of the evolution of the two post-treatment process in the orientation of the molecule structure and conformation of RSF, i.e. method A (fiber first soaked in 80 vo1% aqueous solution of ethanol, 1H, then in the hot steam is stretched by 2 times), and Method B (first in a 80 vol% ethanol aqueous solution in the fiber is stretched by 2 times, and then soaked in the solution for one hour). Explore the relationship between fiber structure change and improvement in mechanical properties, the results show that the tensile than only soaked in aqueous ethanol is more conducive to the conformational transition of silk fibroin in aqueous ethanol or hot steam, and also to improve the silk fibroin molecules the orientation of the chain is more efficient. Compared with the Method A, Method B can enhance the degree of orientation of the fibers, the content and the mechanical properties of the p-sheet conformation. Achieved through improved processing apparatus manually after stretching effect of the treatment is unstable mechanical stretching, the apparatus having a precise measurement, convenience of operation and other characteristics. Tensile rate, the draw ratio after the fiber structure and properties, and to explore the results of the post-processing of the sample diameter and data processing methods, in order to further optimize the RSF fibers stretch of single-stage post-treatment processes. The study showed that the fiber after stretching treatment, the mechanical performance depends primarily on the supramolecular structure formed in the stretching process, the fiber orientation state, crystalline and morphology. Draw ratio is more than the stretching rate to improve the structure and mechanical properties of the fibers. The treatment process can be a substantial increase in the single-stage stretching or multi-stage stretching the RSF protofibers mechanics performance, single-stage stretching process better. After the RSF protofibers in 80 vol% aqueous ethanol with 0.9 mm / s of tensile rate uniformly stretched to 4 times, and then soaked in the solution for 1 hour, the breaking strength of the fiber-TAT (326.7 ± 97.8) MPa up to protofibers 10 times; fracture can be reached (39.7 ± 10.1) kJ · kg-1, up to 150 times the fiber of the newborn, and are superior to natural degummed silk. The highest breaking strength fiber handling multi-stage stretching up to six times protofibers highest fracture energy of up to 90 times the protofibers.

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