T700级炭纤维表面特性及其对复合材料界面性能的影响

Surface characteristic of T700 grade carbon fibers and effect on interfacial properties of composites

以不同厂家生产的3种T700级炭纤维T700SC、UT500和CFT700为研究对象,采用SEM、AFM对纤维的表面形貌和粗糙度进行表征,通过表面/界面张力仪对炭纤维的表面能和浸润性能进行分析,然后对炭纤维/环氧618复合材料的层间剪切强度和断面形貌进行分析,以探讨炭纤维表面特性和浸润性能与复合材料界面性能的关联。结果表明,T700SC纤维表面光滑,粗糙度较小,UT500和CFT700纤维呈现表面沟槽状态,粗糙度较大。与T700SC纤维相比,UT500和CFT700纤维表面能更高,与环氧树脂具有更好的浸润性能。ILSS测试和断面分析结果表明,T700SC纤维复合材料ILSS为67.34 MPa,界面结合较差;UT500和CFT700复合材料ILSS分别为79.54 MPa和85.69 MPa,界面结合较好。炭纤维浸润性能与复合材料的宏观ILSS性能具有较好的一致性。

Three types of T700 grade carbon fibers T700SC, UT500 and CFT700 produced by different producers were selected as research objective. The scanning electron microscope （SEM） and atomic force microscope （AFM） were applied to characterize the surface morphologies and roughness of these carbon fibers. The surface energy and wettability of the three type fibers were investi- gated by surface tension-meter. Then the interlaminar shear strength （ILSS） and fracture morphology of carbon fiber reinforced epoxy composites were analyzed. Finally, the relationship between wettability of carbon fibers and the interfacial properties of the compos- ites was discussed. The results show that the surface of carbon fiber T700SC is smooth and the roughness is lower, while the surfaces of carbon fibers UT500 and CFTT00 have wrinkles and the roughness is higher. As compared with T700SC, UT500 and CFT700 have higher surface energy and better wettability with epoxy resin. The results of ILSS testing and fracture morphology analysis show that the ILSS of T700SC fiber composite is 67.34 MPa and presents poor interfacial coupling strength. In comparison, the ILSS of UT500 and CFTT00 composites are 79.54 MPa and 85.69 MPa respectively and show better interfacial coupling strength. The wettability of carbon fiber and the ILSS of composites present good consistency.