Fatigue Behavior of Aramid Nonwoven Fabrics Under Hot-Press Conditions

Abstract

Nonwovens used as components of laminated cushion materials for multi-daylight press molding are subjected to repeated hot-press fatiguing. Preferred heat-resistant nonwovens show little change in mechanical properties such as tensile and compression after repeated fatiguing. In Part III, needle-punched nonwovens had superior recovery from hot-press fatiguing compared with paper-like nonwovens and four-ply wovens, because the 3-D fiber arrangement (fibers arranged in the thickness direction) provided by the needle caused these fibers to behave like springs in the nonwovens. In Part VI, the 3-D fiber arrangement was maintained by the stable base fabrics after repeated fatiguing, and was one of the important factors determining the mechanical properties of these nonwovens. The 3-D fiber arrangement can be mainly constructed by the barb and throat of the needle. In this study, we discuss the influences of the barb and throat shapes on fiber arrangement and fiber-to-fiber entanglement. In particular, we discuss the relationship between the cross-sectional area of the throat and compression-recovery properties. Three kinds of nonwovens prepared with different needle types are subjected to repeated hot-press fatiguing treatments, and their compression-recovery behaviors are analyzed. The nonwoven made by the needle with the large cross-sectional throat area is thinner, very elastic, and provides good recovery from compression. This is because the fibers arranged in the thickness direction by the needles get more tightly entangled and may behave somewhat like springs during compression and recovery.