硅溶胶改性天然乳胶薄膜的制备及其性能研究

发布时间：2018-07-29 18:43

【摘要】：天然乳胶是一种经生物合成的、可再生的自然资源。因其优异的弹性和成膜性,被广泛地应用于医用弹性薄膜制品领域。但是纯天然乳胶薄膜的拉伸强度不高、耐溶剂性和致密性较差等缺陷在一定程度上限制了天然乳胶的应用发展。本文利用硅溶胶、阳离子聚电解质改性硅溶胶以及大豆蛋白／二氧化硅杂化溶胶分别对天然乳胶进行改性,获得一系列结构可控的有机-无机复合材料,所得膜材料的机械性能、耐溶剂性和致密性均得到不同程度的改善。本课题以正硅酸乙酯(TEOS)作为前驱体,在其水解缩聚生成硅溶胶的不同阶段共混改性天然乳胶。研究结果表明共混胶乳中原位生成的纳米Si02能够有效地提高薄膜的力学性能,同时薄膜的亲水性和耐紫外老化性能也得到了提高,但仍存在Si02向薄膜表面迁移的问题,影响了原位补强的效果。进一步用阳离子聚电解质对硅溶胶中的SiO2胶粒进行包覆改性后,带正电性的Si02胶粒能与带负电的天然乳胶粒子形成一种以乳胶粒子为核、SiO2胶粒为壳的核壳结构,这种紧密的核壳结构能够提高膜材料中有机无机两相之间的交联程度,进而提高薄膜的力学性能和耐溶剂性,同时解决了Si02向膜表面迁移的问题。大豆蛋白具备良好的成膜性和界面结合能力,能够与乳胶表面的非胶物质结合,并且大豆蛋白中的极性基团容易和其他官能团构成物理或化学交联点。本文通过TEOS在大豆蛋白溶液中的水解缩聚反应,制备出一种大豆蛋白／二氧化硅杂化溶胶,用于改性天然乳胶。研究表明这种杂化溶胶能够填补乳胶粒子间的空隙,改性薄膜在力学性能大幅提高的同时,薄膜表面的致密性和耐溶剂性也均得到明显改善。
[Abstract]:Natural latex is a biologically synthesized, renewable natural resource. Because of its excellent elasticity and film forming, it is widely used in the field of medical elastic film products. However, the tensile strength of pure natural latex film is not high, and the poor solvent resistance and compactness limit the application of natural latex to some extent. In this paper, a series of organic-inorganic composites with controllable structure were obtained by using silica sol, cationic polyelectrolyte modified silica sol and soybean protein / silica hybrid sol respectively. The mechanical properties, solvent resistance and densification of the films were improved to some extent. In this paper, tetraethyl orthosilicate (TEOS) was used as the precursor, and the natural emulsion was blended in different stages of hydrolysis and condensation to produce silica sol. The results show that the in-situ nanosized Si02 can effectively improve the mechanical properties of the films, and the hydrophilicity and UV aging resistance of the films are also improved, but there is still the problem of Si02 migration to the surface of the films. The effect of in-situ reinforcement is affected. After further modification of SiO2 particles in silica sol with cationic polyelectrolyte, the positively charged Si02 particles can form a core-shell structure with latex particles as core SiO2 particles and negative charged natural latex particles. The close core-shell structure can improve the cross-linking degree between organic and inorganic phases in the membrane materials, and then improve the mechanical properties and solvent resistance of the films. At the same time, the problem of Si02 migration to the surface of the membrane can be solved. Soybean protein has good film-forming and interfacial binding ability, and can bind to non-colloidal substance on the surface of emulsion, and the polar group in soybean protein can easily form physical or chemical crosslinking point with other functional groups. In this paper, a soybean protein / silica hybrid sol was prepared by hydrolysis and condensation of TEOS in soybean protein solution, which was used to modify natural latex. The results show that the hybrid sol can fill the gap between latex particles and the surface densification and solvent resistance of the modified films are improved significantly while the mechanical properties of the modified films are greatly improved.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB383.2

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