Fatigue Behavior of Aramid Nonwoven Fabrics Under Hot-Press Conditions PartⅡ: Geometric Structure of Fiber Cross Sections

摘要

Relationships between the mechanical properties and geometric fibrous configurations for aramid and polyamide nonwoven fabrics under hot-press fatigue are discussed. In order to examine fiber configurational changes in nonwoven fabrics under compression, image data of fabric cross sections prepared for observation were input in a computer processing system, and the cross-sectional configuration of the fibers, cross-sectional area, circle index of fiber configuration, and packing factors were computed. The tensile breaking strength and tensile maximum modulus of polyamide nonwoven fabrics decreased despite the increase in the fibrous packing factor of the fabrics, while those' of aramid nonwoven fabrics increased. This may be attributed to the difference in high-temperature resistant properties between the two fiber types. The compressive modulus of both nonwovens increased similarly as their packing factors increased. It is clear that the very high compressive modulus of Ny fabrics, which is nearly the same as that of Nx fabrics, is caused by the high packing factor of Ny, higher than that of Nx fabrics.