【作者】 陈科宇；

【导师】 汪长安；

【作者基本信息】 清华大学 ， 材料科学与工程， 2009， 硕士

【摘要】 在过去的十几年中,蒙脱土以其独有的性质,在粘土/聚合物基纳米复合材料的制备中,得到了充分的重视和十分广泛的研究。本文主要利用蒙脱土晶片在水中的荷电性质和优异的片层结构,将电泳沉积的方法引入到蒙脱土/聚合物纳米复合材料的制备中,并分别选取绝缘的丙烯酸阴极电泳树脂和导电的聚吡咯作为有机基体,开展了两方面的工作。一方面,利用蒙脱土与丙烯酸阴极电泳树脂的良好相容性,以及丙烯酸阴极电泳树脂分子中季铵根对蒙脱土的插层作用,我们直接从水溶液中通过电泳沉积成功地制备了丙烯酸阴极电泳树脂/蒙脱土复合膜(涂层)。XRD、SEM、TEM等表征的结果以及静态拉伸、纳米压痕等测试的结果说明:复合膜结构均一、蒙脱土在树脂基体中分散良好,蒙脱土的加入有效地提高了复合膜的杨氏模量、纳米压痕模量和硬度,拉伸强度随蒙脱土添加量的增大呈现先升高后降低的趋势。我们对复合涂层按照国标进行了柔韧性、黏附力和耐水性测试,发现蒙脱土的引入并没有造成丙烯酸阴极电泳树脂涂层柔韧性和黏附力的降低,但光泽度和耐水性略有下降。由于丙烯酸阴极电泳树脂是作为底漆而不是面漆使用的,因此光泽度和耐水性的稍许下降并不影响我们的设计目的。另一方面,采用导电聚合物聚吡咯,取代绝缘的丙烯酸阴极电泳树脂作为基体,并通过电化学沉积的方法制备和表征了聚吡咯/蒙脱土纳米复合薄膜和涂层。利用聚吡咯的良好导电性,使电泳沉积连续进行,从而实现了对复合薄膜的厚度控制,并合成了较厚的复合薄膜,得到了高度有序的有机/无机层状复合结构。另外,通过静态拉伸、纳米压痕等测试发现,在引入少量的蒙脱土后,复合薄膜和涂层的拉伸强度、纳米压痕模量和硬度都得到了明显提高,但当蒙脱土含量进一步提高之后,复合膜或涂层的这些力学性能反而降低。另外,随着蒙脱土的引入,复合膜的电导率也随着蒙脱土含量的增大而呈现出先增大后减小的趋势。更多还原

【Abstract】 In the past decade, montmorillonite (MMT), due to its specific characteristics, has been extensively studied in the preparation of clay/polymer matrix nanocompoistes. Taking advantage of high aspect ratio of MMT platelets and negative charges on their basal faces, this work introduced the method of electrophoretic deposition (EPD) into preparation of MMT/polymer matrix nanocomposites. For a comparison, insulated cathodic electrophoretic acrylic resin (CEAR) and electrically conductive polypyrrole (PPy) were employed as the polymer matrix, respectively, and two kinds of composites were investigated.The first part of our work is the construction of CEAR/MMT nanocomposite films and coatings by EPD. Given the compatibility between MMT and CEAR, and the intercalation of CEAR molecular into NMMT platelets, we prepared the CEAR/MMT nanocomposite films and coatings from the aqueous electrolyte directly. XRD, SEM, TEM, tensile testing and nano-indentation showed good dispersion of MMT in polymer matrix and effective improvement in modulus, strength and hardness. Coating testing showed good flexibility and adhesive force maintained after introduction of MMT but a little decrease in water resistance.The second part is the preparation of PPy/MMT nanocomposite films and coatings by EPD, in which we replaced insulated CEAR with electrically conductive PPy. Due to the excellent conductivity of PPy, pyrrole monomer deposited on the electrode and polymerized continuously. As a result, the thickness of films can be controlled by deposition time, in other words, highly ordered composite films could be obtained under a relatively long deposite time. Tensile testing and nano-indentation showed a great improvement of the mechanical properties including modulus, strength and hardness when clay loading was relatively low. And also the electric conductivity of composite films improved for the restrict growth of PPy in the interspace of NMMT platelets.更多还原