Fatigue Behavior of Aramid Nonwoven Fabrics Under Hot-Press Conditions

Abstract

To develop heat-resistant nonwoven fabrics, nonwovens were subjected to repeated hot-press fatigue, and the mechanical properties of and configurational changes in the fabrics were examined. The mechanical properties of nonwovens depend on raw ma terials, fiber fineness, fiber length, needle punching density (numbers), fiber arrange ment, and structural differences resulting from differences in manufacturing. This paper reports on geometric structural influences on the mechanical properties of non woven fabrics after hot-press fatigue. We prepared two kinds of nonwovens using either the paper-making method or a needle punching machine, and one kind of woven fabric made on a four-ply weaving machine, and we investigated the influences of the fabrics' geometric structures on their compressive behavior. We expected that four-ply woven fabric would show better compressive behavior than the other non woven fabrics because it contains a lot of air. Our investigation showed, however, that the four-ply woven fabric behavior was very similar to that of the paper-like nonwoven fabric, while the needle-punched nonwoven behaved very differently from the others. In particular, we found that the needle-punched nonwoven fabric had good fatigue resistance and recovery properties, as shown by its small increase in compressive mod ulus and small change in compressive strain with fatigue cycles.