【作者】 张宇强；

【导师】 许忠斌；

【作者基本信息】 浙江大学 ， 材料科学与工程， 2008， 硕士

【摘要】 在高聚物共混物中加入炭黑制备导电高聚物是近年高分子材料共混领域中的研究热点之一,高聚物共混物的相分离和炭黑选择性地分散到某一相中,能够在炭黑用量较低的情况下获得高电导率的复合材料,另一方面能够提供比较好的加工性能,并且有效减弱因填料含量较高时造成的机械性能下降的影响。本文以炭黑粒子为导电填料,聚酰胺6为主要聚合物基体,在HAAKE转矩流变仪中制备了PA6/PS/CB、PA6/PAN/CB等导电复合材料,研究了炭黑粒子的分散形态、共混体系相形态、共混体系流变行为特点,以及它们与炭黑/聚合物共混体系导电性能的关系。采用扫描电镜观察、透射电镜观察、炭黑粒子迁移现象观察,以及溶剂选择溶解等方法,考察了炭黑粒子在PA6/PS和PA6/PAN共混体系中的选择性分散情况,得到炭黑粒子都选择性的分散在PA6相中的一致结果。炭黑/聚合物共混体系中炭黑含量一定时,炭黑富集相中炭黑含量与炭黑富集相的连续状态共同影响体系导电能力,炭黑富集相含量相对较少时更有利体系导电性能的提高;炭黑富集相含量相对较少且保持连续状态时,体系导电能力达到最大值。研究了PA6/PS/CB共混体系的动态流变行为。结果表明,共混体系表现出自相似性的黏弹行为;炭黑填充聚合物共混体系的G’等曲线均位于炭黑填充单一组分相应曲线之间,且G’随PS含量的增加而增大,说明炭黑填充二元聚合物复合材料比炭黑填充一元聚合物复合材料更有弹性。对炭黑/聚合物共混体系动态力学行为的研究结果表明,炭黑导电粒子的加入对聚合物共混体系起到了增强作用,随着炭黑填充量的增加复合材料的储能模量也在提高,并且填料的加入使体系的玻璃化转变温度略往高温处移动:共混体系的E’均随温度的升高而呈现逐渐降低的趋势,E’显著变化的区域分别对应不同的力学状态;PS组分的加入能提高复合材料对温度变化的敏感性:PA6/PAN/CB共混体系的E’随PAN含量的增加而提高,共混体系出现力学损耗峰的温度随PAN含量的增加而提高,并且损耗因子tanδ值变小。PAN组分的加入提高了复合体系的机械性能和耐热性能。结合DMA、DSC、TEM等实验方法,研究了PA6/PAN/CB共混体系的相形态以及其与材料导电性能的关系。结果表明,PA6与PAN相呈现部分相容性的特点;随着PAN组分的增加复合体系出现微相分离结构,并且PAN组分的加入能诱使一部分炭黑粒子分散到PA6、PAN两相界面处,在这两种作用下,PA6/PAN/CB共混体系的导电性能得到提高。更多还原

【Abstract】 Polymers filled with carbon black (CB) have been extensively studied and used when appropriate conductivity levels are required. One of the recent trends is to reduce the CB content in composites while maintaining a relatively high conductivity at the same time. The selective distribution of CB into one phase or at the interface of polymer blends can bring on electric conductive materials with lower filler content. This can also provide good processing ability and avoid poor mechanical properties in consequence of high CB content. There are several factors affecting the electric conductivity of CB-filled polymer blends and the mechanism of the electric conductivity has not been clear yet. In this dissertation, sseveral sorts of CB-filled nylon6 (PA6) composites were prepared in HAAKE Thermo-mixer. The morphology, conductivity, thermorheology properties and their relationships were studied.The dispersion states of CB particles in polymer blends were characterized by different methods. The results show the same: CB particles distributed predominately in the PA6 phase in PA6/PS/CB, PA6/PAN/CB composites. The results also show that when CB particles located preferentially in one polymer phase, the ternary composites have the highest electric conductivity usually when the amount of the polymer component in which the CB particles distribute is comparatively less than the polymer component in which the CB particles do not distribute. The addition of PAN component can attract a part of CB particles that transfers to the interface of PA6 and PAN. This makes the formation of a better network structure of CB, and the electric conductivity of the composites increases as a consequence.Studies on the linear viscoelastic behavior of PA6/PS/CB blends were carried out. The results show that polymer blends performance a similarity viscoelastic behavior of the original component. The elastic modulus of PA6/PS/CB composites increases as the CB or PS content increases. CB-filled binary polymer blends show more elastic than CB-filled unitary polymer. The studies on the thermorheological properties of CB-filled PA6 composites demonstrate that while the PAN content in PAN/PA6/CB blends rises, the elastic modulus of the blends increases and tan 5 values of the blends decreases as compared with the PA6/CB composites. The presence of PAN particles enhances the mechanical performance of conductive PA6/CB composites at high temperatures.When a small mass of PAN was introduced into PA6/CB composites, micro-phase separation structures and partial miscibility were confirmed by Advanced Rheometric Expansion System, DMA, TEM and DSC tests. A part of CB particles could be attracted by PAN, and transferred to the interface of PA6 and PAN, leading to an increase of electric conductivity.更多还原