聚合反应时间对聚酰亚胺基碳膜结构和性能的影响研究

目的 系统研究前驱体聚合反应时间对PI膜及其碳化、石墨化后薄膜结构和性能的影响规律。方法 通过调整聚合合成聚酰胺酸(PAA)溶液过程中的反应时间，制备石墨膜前驱体聚酰亚胺(PI)原膜，将不同工艺条件下制得的PI膜进行碳化、石墨化处理，得到高导热率石墨膜。利用扫描电镜、红外光谱、拉曼光谱仪和LFA激光闪射仪对制备的PI膜、碳化膜及石墨膜的微观结构和热导率进行检测。结果 随聚合反应时间的延长，PI膜酰亚胺化程度和石墨膜的石墨化程度及导热性能先增高、后降低。反应时间为3 h时，制得的石墨膜结构致密，石墨片层取向性好，导热性能最好，热导率可达765.2 W/(m.K)。结论 PI膜前驱体聚合反应时间显著影响PI膜酰亚胺化的程度和有序度，进而影响石墨膜的定向性和导热性能。

Effects of Polymerization Time on the Microstructure and Properties of PI-based Carbon Films

The purpose of this paper is to systematically study the effect of precursor polymerization time on the structure and properties of PI films and their carbonized and graphitized films. In this paper, by adjusting the reaction time in the polymerization process of polyamic acid (PAA) solution, the polyimide (PI) original films were prepared, which were the precursor of graphite films. The PI films prepared under different process conditions were carbonized and graphitized to obtain high thermal conductivity graphite films. The microstructure and thermal conductivity of PI films, carbon films and graphite films were measured by SEM, FTIR Spectrometer, Raman Spectrometer and LFA laser flash analyzer. The results show that with the increase of polymerization time, the degree of imidization of PI films, the degree of graphitization and the thermal conductivity of graphite films first increased and then decreased. When the reaction time was 3 h, the graphite film prepared had the most compact structure, good orientation of graphite sheet and the best thermal conductivity, with the thermal conductivity could reach to 765.2 W/(m.K). The polymerization time of PI film precursor significantly affects the imimidedegree and order of PI film, and then affects the orientation and thermal conductivity of the graphite film.