双逾渗高分子导电复合材料的结构与性能研究

发布时间：2018-07-02 07:22

本文选题：双逾渗 + 高分子导电复合材料　；参考：《青岛大学》2017年硕士论文

【摘要】：高分子导电复合材料是将导电填料填充到聚合物基体中而形成的一类具有导电性能的高分子复合材料。由于具有优良的可加工性、可调控的导电性能以及广泛的应用领域,高分子导电复合材料受到学术界和工业界的广泛关注。然而,目前往往需要向聚合物基体中填充大量的导电填料才能使高分子复合材料实现由绝缘到导电的转变,这不仅提高了材料的制造成本,也降低了材料的力学性能和加工性能。因此,如何制备具有超低导电逾渗阈值的高分子导电复合材料成为人们研究的热点。研究表明,将导电填料填充到具有双连续结构的不相容共混体系中,利用双逾渗效应可以有效地降低高分子导电复合材料的导电逾渗阈值。但是,由于不相容共混体系中两相间相容性差,界面黏附力小,具有双逾渗结构的高分子导电复合材料的力学性能存在一定的缺陷。因此,本文主要围绕如何降低高分子导电复合材料的导电逾渗阈值并提高其力学性能开展了一系列的研究工作,主要的研究结果如下:1.本文设计了一种简单、有效的热力学方法将多壁碳纳米管(MWCNTs)精确地调控到具有双连续结构的聚苯乙烯(PS)/聚甲基丙烯酸甲酯(PMMA)共混体系的相界面,进而制得了具有超低导电逾渗阈值的高分子导电复合材料。这种MWCNTs界面分布的实现是由于MWCNTs表面与PS之间的?-?相互作用和MWCNTs表面的羧基基团与PMMA之间的偶极-偶极相互作用的相互平衡。研究发现,当MWCNTs表面羧基基团的含量为0.73 wt%时,?-?相互作用能够与偶极-偶极相互作用达到平衡,此时MWCNTs可以被精确地调控到PS/PMMA的相界面。由于MWCNTs在双连续相的界面形成导电网络,PS/MWCNTs/PMMA复合材料的导电逾渗阈值由1.81 wt%(MWCNTs/PS复合材料的导电逾渗阈值)或1.46 wt%(MWCNTs/PMMA复合材料的导电逾渗阈值)降低至0.017 wt%,这是目前文献报道的一个非常低的导电逾渗阈值。2.本文利用双逾渗效应制备了导电逾渗阈值为1.45 wt%的炭黑(CB)/PS/聚丙烯(PP)(PS/PP=60 w/40 w)高分子导电复合材料。然而,由于PS、PP不相容共混体系的界面黏附力弱,CB/PS/PP(60 w/40 w)高分导电复合材料的力学性能较差。尽管增容剂聚(苯乙烯-乙烯-丁烯-苯乙烯)(SEBS)三嵌段共聚物的添加可以显著地提高复合材料的力学性能,但是当SEBS的含量超过3 wt%时,该复合材料的导电性能却大幅度降低。这是由于增容剂SEBS的加入会减小不相容共混体系的相尺寸,进而破坏双逾渗结构中的两相连续性。研究发现,当SEBS的含量为2 wt%时,CB/SEBS/PS/PP(60 w/40 w)复合材料仍然保持着较好的双逾渗结构,材料不仅具有优异的导电性能,而且其力学性能也得到显著地提高。因此,通过加入适量的增容剂SEBS(2 wt%)可以很好地平衡具有双逾渗结构的CB/SEBS/PS/PP(60 w/40 w)高分子导电复合材料的导电性能和力学性能。
[Abstract]:Polymer conductive composite is a kind of conductive polymer composite which is filled with conductive filler in polymer matrix. Due to its excellent processability, controllable conductivity and wide application fields, polymer conductive composites have attracted extensive attention from academia and industry. However, it is often necessary to fill the polymer matrix with a large number of conductive fillers in order to achieve the transition from insulation to conductivity in polymer composites, which not only increases the cost of manufacturing materials. The mechanical properties and processing properties of the materials are also reduced. Therefore, how to prepare polymer conductive composites with ultra-low percolation threshold has become a hot research topic. The results show that the double percolation effect can effectively reduce the percolation threshold of polymer conductive composites by filling conductive fillers into incompatible blends with double continuous structure. However, the mechanical properties of polymer conductive composites with double percolation structure have some defects due to the poor compatibility between the two phases and the small adhesion between the two phases in the incompatible blends. Therefore, this paper focuses on how to reduce the percolation threshold and improve the mechanical properties of polymer conductive composites. The main results are as follows: 1. In this paper, a simple and effective thermodynamic method has been designed to precisely regulate the multi-walled carbon nanotubes (MWCNTs) to the phase interface of polystyrene (PS) / polymethyl methacrylate (PMMA) blends with double continuous structure. Furthermore, polymer conductive composites with ultra-low percolation threshold were prepared. The realization of the interfacial distribution of MWCNTs is due to the interfacial distribution between MWCNTs and PS. The equilibrium of the dipole-dipole interaction between the carboxyl groups on the surface of MWCNTs and PMMA. It was found that when the content of carboxyl group on the surface of MWCNTs was 0.73 wt%, the content of carboxyl group was 0.73 wt%. The interaction can reach equilibrium with dipole-dipole interaction, where MWCNTs can be accurately regulated to the phase interface of PS- / PMMA. The percolation threshold of PS / MWCNTs / PMMA composites decreased from 1.81 wt% (the percolation threshold of MWCNTs / PMMA) or 1.46 wt% (the percolation threshold of MWCNTsP / PMMA) to 0.017 wts. this is the current literature. A very low percolation threshold. 2. In this paper, the conductive composites of carbon black (CB) / PS / PP (PS / PP) (60 w/ 40 w) with conductive percolation threshold of 1.45 wt% were prepared by double percolation effect. However, the interfacial adhesion of PS / PP / PP / PP (60 w / 40 w) high content conductive composites is poor because of the weak interfacial adhesion. Although the addition of the compatibilizer (styrene butene styrene) triblock copolymers can significantly improve the mechanical properties of the composites the electrical conductivity of the composites decreases significantly when the content of SEBS exceeds 3 wt%. This is because the addition of compatibilizer SEBS will reduce the phase size of the incompatible blend system and thus destroy the two-phase continuity in the double-percolation structure. It is found that when the content of SEBS is 2 wt%, CBP / SEBS / PS / PP (60 w/ 40 w) composites still maintain a good double percolation structure. The composites not only have excellent electrical conductivity, but also their mechanical properties have been significantly improved. Therefore, by adding proper amount of compatibilizer SEBS (2 wt%), the conductive and mechanical properties of CB/ SEBS / PS-PP / PP (60w / 40w) composites with double percolation structure can be well balanced.
【学位授予单位】：青岛大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332

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