Through adding 2-methyimidazolium cobalt (ZIF-67) nano-fillers into 3,3′,4,4′-biphenyltetracarboxylic anhydride (BPDA) - 4,4′-diaminodiphenyl ether (ODA) type polyimide (PI) matrix, we prepared a PI/ZIF-67 three-layer composite films with sandwich structure. The structure of ZIF-67 and PI/ZIF-67 three-layer composite films were characterized by FTIR, XRD, and SEM, and the effect of ZIF-67 content on the thermal stability and dielectric property of the composite films was studied. The results show that when the mass fraction of ZIF-67 is less than 10%, the initial decomposition temperature of composite film is higher than 500℃, which shows good thermal stability. The dielectric constant of PI/ZIF-67 composite films is obviously lower than that of PI. When the mass fraction of ZIF-67 is 10%, the dielectric constant of PI/ZIF-67 composite film decreases by 50%. When the mass fraction of ZIF-67 is 5%, the dielectric constant of PI/ZIF-67 composite film decreases by 71%. When the mass fraction of ZIF-67 is less than 10.0%, the dielectric loss of PI/ZIF-67 composite film is slightly higher than that of pure PI.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |