Hygrothermal mechanical properties of carbon fabric/epoxy composites toughened by structural toughening layer of polyamide non-woven fabric

U3160 carbon fabric reinforced 3266 epoxy composites toughened by polyamide nonwoven fabric (PNF) (U3160-PNF/3266) were fabricated using PNF as structured toughening layer. Both the in-plane mechanical properties of U3160-PNF/3266 composites and the effect of hygrothermal ageing on mechanical properties were investigated. The interlaminar morphological analysis of the composites was also performed before and after hygrothermal ageing. The results show that the use of PNF as toughening layer does not lead to the decline of in-plane mechanical properties of composites. Meanwhile tensile properties of the toughened U3160-PNF/3266 composites in 90° even slightly increase compared with untoughened U3160 carbon fabric reinforced 3266 epoxy (U3160/3266) composites. While the matrix and interfacial properties of U3160-PNF/3266 composites are noticeable influenced by hygrothermal ageing, especially for the interfacial bonding property between the nylon fiber and the resin matrix. The retention rates of properties of compression in 90° and interlaminar shear of the toughened composites are lower than those of the untoughened composites obviously after hygrothermal ageing.