环境友好大豆蛋白质材料改性研究

发布时间：2018-01-09 07:07

本文关键词：环境友好大豆蛋白质材料改性研究　出处：《北京化工大学》2015年博士论文　论文类型：学位论文

【摘要】：由于环境污染的加剧及石油基资源的日益短缺,基于可再生资源的生物材料日益受到重视。大豆蛋白质是豆油产业的副产物,是一种来源丰富的可再生植物资源,也是一类添加增塑剂后可热塑成型的天然高分子材料。然而,单独由大豆蛋白质制备的塑料硬且脆,加入小分子增塑剂后,大豆蛋白质热塑性改善,柔韧性增加,但力学强度较低且对水敏感,限制了其发展和应用。本论文以大豆分离蛋白质(SPI)为主要原料,通过与其他生物可降解材料的共混,以及与纳米粒子的复合来得到廉价、加工性良好且力学及防水性能改善的大豆蛋白质环境友好材料。在表征材料的结构、性能以及评价材料应用前景的同时,探讨材料结构与性能之间的关系。本论文的创新之处在于：(1)制备了邻苯二甲酸酐改性的大豆蛋白质(PAS)并用其来增强甘油增塑的大豆蛋白质,在不添加任何增容剂的情况下得到了两相相容性良好、性能改善的大豆蛋白质复合材料,探讨填料、基体相似的化学结构与相容性之间的关系；(2)将碳纳米管进行酸改性后与大豆蛋白质复合,得到分散性良好、增强效果明显的纳米复合材料,研究酸改性后纳米管表面极性的变化对其在基体中的分散以及与基体相容性的影响；(3)在无增塑剂添加的情况下,通过熔融共混制备了全生物降解的SPI/聚己二酸/对苯二甲酸丁二酯(PBAT)共混材料,该共混材料在高蛋白质填充量的情况下仍具有较好的韧性和强度；(4)首次通过熔融法制备了SPI/聚乙烯醇(PVA)共混膜材料,制备过程简单、绿色且产品性能优良；为了进一步改善共混材料的力学性能,继而在SPI/PVA材料中引入层状硅酸盐蒙脱土(MMT),利用SPI/PVA与MMT三者间强的氢键作用制备剥离型或插层型纳米复合材料,所得材料强度、热稳定性、防水性提高。本论文的主要内容和结论包括如下几个方面：(1)通过化学改性制备了N-邻苯二甲酰化大豆蛋白质(PAS),并用它与甘油增塑的大豆分离蛋白质(GPS)复合得到PAS/GPS复合材料。由于极性基团的减少以及苯环的空间位阻,在与甘油混合时,PAS已失去热塑性,因而,在复合材料中可发挥增强填料的作用。由于PAS与GPS基体间有相似的化学结构,因此两相表现出良好的相容性,所得复合材料透光性较强且力学性能明显改善。随着填料含量的增加,复合材料强度和模量显著提高。由于PAS的疏水性以及填料-基体间强相互作用,也使复合材料的疏水性增加。PAS的热稳定性略低于SPI,因此整个复合材料的热稳定性略微降低。(2)通过酸处理制备改性多壁碳纳米管(MWCNTs),并将其引入到甘油增塑的大豆蛋白质中制备纳米复合材料。酸处理可改善碳纳米管的团聚且在碳纳米管表面引入极性基团。经酸改性处理后的碳纳米管在蛋白质基体中分散均匀,与基体相容性良好。碳纳米管并未改变大豆蛋白质原有结晶结构。鉴于碳纳米管与大豆蛋白质基体之间的强氢键相互作用及在基体中的均匀分散,加入碳纳米管后,复合材料的力学性能明显改善,碳纳米管在蛋白质基体中表现出了明显的增强效果。由于SPI和碳纳米管之间强氢键相互作用阻碍了蛋白质基体在高湿度环境下的溶胀,因此加入碳纳米管后,复合材料的吸水率降低。此外,碳纳米管还显著提高了复合材料的热稳定性。(3)通过将SPI与PBAT熔融共混制备了一种新型生物降解塑料。共混材料的结构为海岛结构,并且依赖于SPI含量。SPI含量低时(9.1%)两相相容性较好,含量进一步增加会出现一定程度相分离。SPI和PBAT之间存在相互作用,SPI起到了增强效果,随着SPI含量的增加,共混材料的储能模量及玻璃化转变温度提高。共混材料的拉伸强度及断裂伸长率随SPI含量的增加而降低,但在SPI含量高达28.6%时共混材料仍具有良好的韧性。大豆蛋白分子中含有大量的亲水基团,表现出强的吸水性,导致SPI/PBAT材料吸水率的增加。随SPI含量的增加,SPI/PBAT共混材料的热稳定性在200-400℃范围内降低,而在更高的温度下热稳定性提高。共混膜具有良好的生物降解性能。在土壤中SPI比PBAT更易降解,因此,含SPI的共混材料比纯PBAT降解快。(4)在水存在下用熔融法制备了甘油增塑的SPI/PVA共混膜。PVA的羟基和SPI的酰胺基形成新的氢键,氢键的生成增强了PVA相和SPI相的相互作用,提高了它们的相容性。SPI的存在没有影响PVA的晶体结构,但使PVA的结晶和熔融温度降低。虽然共混膜有一定程度的相分离,但SPI相能均匀的分散于PVA相中,两相相容性较好,使所得共混材料具有优异的力学性能,即使在高蛋白质含量情况下共混材料仍具有很高的韧性。此外,SPI的加入使共混膜的热稳定性和氧气阻隔性能都高于纯PVA膜,但吸水率和水扩散系数增加,防水性减弱。(5)为了进一步提高SPI/PVA薄膜的力学强度,采用熔融加工的方法,制备了SPI/PVA/MMT纳米复合材料。复合材料的结构依赖于MMT含量。当MMT含量≤3.7%时形成剥离结构;MMT含量≥7.1%时形成插层结构。硅酸盐片层表面上的氧原子与蛋白质肽键上的氢原子和PVA分子链羟基上的氢原子产生强氢键相互作用,有助于改善填料与基体之间的相容性。MMT纳米片层可作为PVA的异相成核剂,加速PVA的结晶过程,并增大了其晶体尺寸分布。加工过程中,MMT可明显改善熔体的黏度,因此,随着MMT含量的增加,复合材料熔体黏度增加,剪切作用加强,使蛋白质相分散效果更好。MMT在基体中表现出明显增强作用,随着MMT含量的增加,复合材料的拉伸强度和杨氏模量增加,断裂能先增大后减小,并在MMT含量7.1%时达到最大值。由于高度无序分散的MMT纳米片层对基体链段的有效限制,复合材料的吸水率和水扩散系数降低,热稳定性升高。
[Abstract]:Because of the increasing shortage of environmental pollution and resource base oil, renewable resources of biological materials have been paid more and more attention. Based on soy protein is a by-product of soybean oil industry, is a rich source of renewable plant resources, is also a kind of plasticizer is added after thermoplastic forming natural polymer materials. However, prepared by the soybean protein for separate plastic hard and brittle, adding small molecular plasticizer, soybean protein thermoplastic improvement, increase flexibility, but the mechanical strength is low and sensitive to water, limited its development and application. In this paper, soy protein isolate (SPI) as the main raw material, by blending with other biodegradable materials the composite and nano particles and to obtain cheap, environmentally friendly materials for improving the processing of soybean protein and good mechanical and waterproof properties. In the characterization of materials, materials and performance evaluation Application prospect at the same time, to explore the relationship between the structure and properties of materials. The innovations of this paper are: (1) preparation of phthalic anhydride modified two of soybean protein (PAS) and use it to enhance the soybean protein plasticized with glycerin, without adding any compatibilizer under two-phase good compatibility, improve the performance of soybean protein composite materials, fillers, similar chemical structure matrix and the compatibility relation between; (2) the carbon nanotubes were modified with acid and soybean protein composite, good dispersion, enhanced nano composite effect obviously, acid modified nanotubes change the surface polarity of the dispersion and the influence of compatibility with matrix; (3) in the absence of plasticizer case, were prepared by melt blending biodegradable SPI/ poly adipic acid / benzene of two formic acid (Ding Erzhi PB AT) blends, the blends are filled with good toughness and strength in the case of high protein; (4) for the first time, SPI/ was prepared by melt blending polyvinyl alcohol (PVA) membrane materials, preparation process is simple, green and good performance of the product; in order to further improve the mechanical properties of blends, and then introduce layered silicate montmorillonite in SPI/PVA material (MMT), using SPI/PVA and MMT among the three strong hydrogen bonding preparation of exfoliated or intercalated nanocomposites, the material strength, thermal stability, water resistance is improved. The main contents and conclusions of this paper are as follows: (1) by chemical preparation of modified N- phthalate two formylation of soy protein (PAS), and use it with glycerol added to soy protein isolate plastic (GPS) composite PAS/GPS composite materials. Because of the polar groups to reduce benzene and steric hindrance, and in Glycerol mixed, PAS has lost the thermoplastic, therefore, can play a role in reinforcing fillers in composite materials. Because of the PAS and GPS substrate have similar chemical structure, so the two showed good compatibility, the light transmittance of the composite material is strong and the mechanical properties are obviously improved. With the increase of filler content, composite the material strength and modulus increased significantly. Due to the hydrophobicity of PAS filler matrix and the strong interaction between the hydrophobic, thermal stability of the composites increases.PAS slightly lower than SPI, so thermal stability of the composites decreased. (2) treated by acid preparation and modification of multi walled carbon nanotubes (MWCNTs), and preparation of nano composite materials for soybean protein into the glycerol plasticized. Acid treatment can improve the agglomeration of CNTs and the introduction of polar groups on the surface of carbon nanotubes. The acid modified carbon nanotubes in eggs Uniform dispersion of white matter in the matrix, good compatibility with matrix. Carbon nanotubes did not change the crystal structure of soybean protein. In view of the strong hydrogen bonds between carbon nanotubes and soybean protein matrix interactions in the matrix and uniform dispersion of carbon nanotubes, the mechanical properties of the composites improved significantly in protein matrix in carbon nanotubes the enhancement effect is obvious. The swelling between SPI and carbon nanotubes with strong hydrogen bonding interactions hinder the protein matrix in a high humidity environment, thus adding carbon nanotubes, composite water absorption rate decreased. In addition, carbon nanotubes also significantly improve the thermal stability of the composite. (3) by a new type of biodegradable plastic was prepared by blending SPI and PBAT melt. Structure blends for island structure, and is dependent on the content of SPI at a low concentration of.SPI (9.1%) compared with the compatibility Well, the content will further increase the interaction between.SPI and PBAT to a certain extent of phase separation, SPI has enhanced effect, with the increase of SPI content, the blends of storage modulus and glass transition temperature increased. The tensile strength and elongation of the blends with SPI content increased, but in SPI the content of up to 28.6% when the blend still has good toughness. The soybean protein molecule contains a large number of hydrophilic group, showed strong water absorption, resulting in the increase of SPI/PBAT absorption rate. With the increase of SPI content, the thermal stability of SPI/PBAT blend material at 200-400 DEG C range reduced, and improved the thermal stability in more high temperature. The blend membrane has good biodegradability in soil. SPI more than PBAT easy degradation, therefore, blending materials containing SPI than pure PBAT fast degradation. (4) in the presence of water prepared by melt The amide SPI/PVA blend membrane.PVA glycerol plasticized SPI hydroxyl groups and the formation of new hydrogen bond, hydrogen bond formation enhances the interaction of PVA and SPI phases, improve their compatibility with.SPI had no obvious influence on the crystal structure of PVA, but the crystallization and melting temperature of PVA decreased. Although the blend film is a certain degree of separation, but the SPI phase can be uniformly dispersed in PVA phase, the compatibility is good, the blends have excellent mechanical properties, even in the case of high protein content blends has high toughness. In addition, SPI added that thermal stability and oxygen barrier properties of blend films are higher than that of pure PVA film, but the water absorption rate and water diffusion coefficient increased, water resistance decreased. (5) in order to further improve the mechanical strength of SPI/PVA film, using the method of melt processing, SPI/PVA/MMT nanocomposites were prepared by composite. The structure depends on the content of MMT. When the MMT content is less than 3.7% when the formation of exfoliated structure; MMT content is more than 7.1% when the formation of intercalated structure. Strong hydrogen bonding between the hydrogen atoms of the silicate layers on the surface of the oxygen atom and protein peptide bonds on the hydrogen atom and the hydroxyl groups on the molecular chain of PVA generation, contribute to the modification of nano.MMT the PVA layer can be used as the nucleation agent good compatibility between filler and matrix, accelerate the crystallization process of PVA, and increased the crystal size distribution. In the process, MMT can obviously improve the viscosity of the melt, therefore, with the increase of MMT content, increase the viscosity of composite melt, shear strengthening, the protein.MMT had better dispersion in the matrix showed obvious enhancement effect, with the increase of MMT content, increase the tensile strength and modulus of composites, the fracture energy increases first and then decreases, and reaches the maximum value when MMT content is 7.1%. Due to the high The effective restriction of the disordered dispersed MMT nanoscale to the matrix segment, the water absorption and water diffusion coefficient of the composite decreased, and the thermal stability increased.

【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ316.6

【共引文献】