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Structure Controlling and Properties of Functional Cellulose Composite Materials

Author: WuJunJie
Tutor: CaiYuanLi；XuJian
School: Xiangtan University
Course: Polymer Chemistry and Physics
Keywords: Cellulose Chitin Gel film Composites Catalytic
CLC: TB34
Type: Master's thesis
Year: 2010
Downloads: 110
Quote: 0
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Abstract


Natural polymer, biodegradable materials and renewable resources caused more and more people's attention. Cellulose is a most representative natural polymer. Because of its unique structure and excellent properties, has been widely used in various fields such as industrial production, bio-medicine, environmental engineering. Cellulose is typically a rigid polymer, while a large number of hydroxyl groups contained in the molecular chain make it easy to form intramolecular and intermolecular hydrogen bonds, and thus insoluble difficult financial largely limits the practical application of the cellulose. In recent years, cellulose scientific research focused on the development of new types of solvents and new functional materials. In this thesis, the use of environment-friendly green cellulose solvent system using the new gel developed an excellent mechanical properties of cellulose / chitin hydrogel composite membrane, to study the relationship between the structure and properties of the composite membrane formation mechanism ; development of a new type of cellulose / metal nanoparticle composite microspheres, and try to apply catalytic reduction of nitrophenols synthetic pharmaceutical intermediates aminophenol. This paper will pre-gel method used for the preparation of high-strength cellulose gel film to expand cellulose / chitin hydrogel composite membrane, chitin added and pre-gel conditions change composite membrane structure the impact of the performance. Compared to traditional casting film formation method, the pre-gel method can be obtained a composite film having more closely uniform structure as well as a relatively low degree of crystallinity. The composite membrane structure can be controlled by adjusting the chitin content as well as the temperature of the pre-gel. With the the chitin content increases or pre-gel temperature changes, the pre-gel prepared composite films exhibited a structural change from a dense non-porous to porous. After the first decrease of the degree of crystallinity of the composite membrane with chitin added increases, the relatively low temperatures favor the formation of a film of low crystallinity. The hydrogel prepared composite membrane having excellent mechanical properties, tensile strength and elongation at break is approximately twice that of conventional films. The diffusion behavior of drug molecules in the hydrogel composite membrane the binary diffusion mechanism show that the interaction of its follow Hole mechanism and allocation mechanism. Mechanistic studies have shown that the initial mixed solution gelation process change chitin content regulation, with the chitin content can accelerate or delay the gelation process. Disposable prepared composite membrane of the pre-gel in the regeneration process in the water phase separation mechanism induced by the coagulation bath. Cellulose microspheres of a diameter of about 20μm is prepared based on the sol - gel method, in the emulsifier-containing liquid paraffin. By hydrothermal method, the reaction vessel cellulose microspheres nanopore reactive groups, the use of cellulose Reduction of AgNO by 3 , cellulose / Ag nanoparticle composite microspheres were successfully prepared. The structure and morphology of the synthesized particle size of 30 nm Ag nanoparticles in the composite microspheres can be well dispersed, will not damage the cellulose molecules. Although Ag nanoparticle for the aerobic decomposition of the cellulose having a certain catalytic composite microspheres still have good thermal stability, and will not decompose at 300 oC. To the NaBH 4 Restore Nitrophenols as a model reaction, the composite microspheres in catalysis. Cellulose / Ag composite microspheres efficient catalytic reaction rate is closely related to the catalyst in the content of Ag nanoparticles. This natural polymer matrix prepared a stable and efficient, environment-friendly, reusable metal nanoparticles cellulose composites industry has a bright future.

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