炭黑的“impurity-free”改性及其在聚酰亚胺薄膜中的分散特性研究

IMPURITY-FREE MODIFICATION AND NANO-DISPERSION OF CARBON BLACK IN POLYIMIDE FILMS

利用聚酰胺酸(PAA)在研磨过程形成炭黑(CB)的"impurity-free"分散剂制备纳米CB填充聚酰亚胺(PI)高性能复合薄膜.球磨CB和PAA/N-甲基-2-吡咯烷酮(NMP)溶液的混合液,PAA在研磨过程中降解形成活性分子,原位生成与CB表面具有反应活性和强烈物理吸附能力的"impurity-free"分散剂.拉曼、红外以及紫外-可见光吸收光谱证实了降解PAA分子对CB的改性作用.经改性的CB与PAA溶液共混,涂覆固化制备PI/CB复合薄膜.TEM照片表明该分散剂可以显著促进CB粒子在PI基体中的均匀分散,分散粒径约为200nm.力学性能测试和导电性能测试表明PI/CB复合薄膜的断裂伸长率大幅提高,电阻率(ρ)重复性浮动范围从2个数量级降到1个数量级.进一步研究发现,研磨过程中添加高分子量PAA更有利于CB在PI基体中的均匀分散.

Carbon black （CB）-filled polyimide （PI） composites were prepared using self-degradated low molecular poly（amic acid） （PAA） as impurity-free dispersant. C B and PAA/N-methyl-2-pyrrolidone （NMP） solution were milled in ball miller. The impurity-free dispersant was prepared in the process of in situ degradation of PAA by high-energy milling process,which was active to carbon black （CB） surface. The effect of PAA modification on the CB particles was researched by Raman, IR and UV-Vis. TEM observation showed that the PAA modified CB particles dispersed uniformly in the mixtures with an average CB size of about 200 nm. The toughness, tensile strength and the reproducibility of resistivity for resulted CB/PI composite films were greatly improved. The elongation of resulted CB/PI films was raised at least 50% , and sample-to-sample variation of elongation was decreased from 17% to 11%. The tensile strength variation range was reduced from 12 MPa to 5 MPa. Resistivity variation range was decreased from two orders down to an order. The molecular weight of PAA added in milling progress played an important role on the dispersion of CB. The dispersion uniformity of CB in PI matrix was greatly improved as the increase of PAA molecular weight.