Fatigue Behavior of Aramid Nonwoven Fabrics Under Hot-Press Conditions

Abstract

The purpose of this investigation is to find the most suitable design for heat-resistant nonwoven fabrics to be used as a component of laminated materials. In the earlier parts of the series [1-5], we found that needle punched nonwoven fabrics have superior recovery from pressure compared to paper-like nonwoven and four-ply woven fabrics. The three-dimensional fiber arrangement made by the needle causes these fibers to behave like springs in the nonwoven. The degree of 3-D fiber arrangement depends on needle punching density, and is one of the most important factors that determine the mechanical properties of the nonwoven. But the 3-D fiber arrangement and its effec tiveness gradually diminish after repeated hot-press fatiguing treatments. In this new experiment, we create a needle punched nonwoven by inserting a few stable base fabrics between webs, so that the 3-D fiber arrangement is maintained as long as pos sible even after many hot-press fatiguing treatments. Generally, a stable base fabric is used for dimensional stability and deformation resistance of the nonwoven. We believe that a base fabric in a nonwoven will restric the movability of fibers, so the 3-D fiber arrangement can be maintained, and the recovery from pressure and durability against repeated hot-press fatiguing treatments may be further improved. The nonwovens are made from various base fabrics in different positions between the webs. We also study the effectiveness of the base fabrics on the mechanical properties of nonfatigued non wovens and the changes in their properties with fatiguing.