Fiber Crimp And Crimp Stability In Nonwoven Fabric Processes

Abstract

In nonwovens, crimp characteristics of synthetic fibers are, along with finish, major contributors to processing efficiency, web cohesion, fabric bulk and bulk stability. However, the meaning of measurable crimp parameters and their influence on processing and fabric characteristics has not been quantified. The purpose of this study is to quantify the mechanical fiber behavior during crimp removal, and relate it to fundamental fiber properties, nonwoven fabric properties, and processibility in nonwoven equipment.Single fiber tensile tests in the crimp removal region have been performed on various fibers with the Textechno FAVIMAT and have also been monitored optically. Based on empirical evidence, a basic understanding of the physical crimp removal mechanism is obtained. A methodology is developed, to identify the true crimp removal region of the whole single fiber load-extension curve during a tensile test. A mechanical model accounting for the nonlinear load-deflection behavior during crimp removal is developed. According to this model, a logarithmic function can be used to describe the material behavior in the crimp node during crimp removal. This function is fit to experimental data and delivers two fitting parameters that characterize the shape of the experimental load-extension curve in the crimp region.The extracted characteristic crimp parameters are being evaluated in terms of fiber material characteristics, such as fiber type, crimp processing settings and carding performance during nonwoven production. A dependence of the shape of the crimp removal curve on crimping settings during crimp production is established. The characteristic crimp parameters are also correlated to the sequence of processing stages during nonwoven production and cylinder speed during carding.