To enhance the electrical insulation and mechanical properties of poly(m-phenylene isophthalamide) (meta-aramid, PMIA) nano paper-based materials, a modified alumina (A-Al2O3) with surface-grafted polar groups was prepared using air plasma treatment and introduced into PMIA paper as a reinforcing phase. The effects of different doping amount on the properties of the composite paper were systematically investigated. The results show that when the mass fraction of A-Al2O3 is 3%, the composite paper achieves optimal overall performance, with its breakdown strength increasing to 255.7 kV/mm, volume resistivity reaching 3.48×1015 Ω·m, and the dielectric constant improving while the dielectric loss remaining at a low level. This is attributed to the high insulation performance of A-Al2O3 and its suppression on electric field distortion. At this doping level, the interface trap depth and density in PMIA/Al2O3 composite paper are maximized, effectively inhibiting charge transport and thus enhancing dielectric strength. Additionally, the optimal sample exhibits a Young’s modulus of 3.65 GPa, tensile strength of 24.6 MPa, and elongation at break of 1.5%. This can be attributed to A-Al2O3 bearing more local stress in the insulating paper. However, A-Al2O3 tends to agglomerate when its mass fraction exceeds 3%, leading to decreased dispersion in the matrix, reduced effective interface area, lower trap density, and more stress concentration regions, thereby resulting in deteriorated electrical and mechanical properties of composite paper.
| 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 |