The Influence of Fiber properties and Processing conditions on the characteristics of Needled fabrics.

Abstract

In nonwovens, the inherent fiber crimp characteristics, along with finish determine the processing efficiency and the finished fabric properties like rapid wrinkle recovery, durability, bulk, loft, warmth and resistance to abrasion. Understanding the fiber crimp's influence on the processing properties of nonwoven fabrics has been hampered by the lack of appropriate techniques. Also the carding performance and other process parameters related to different aspects of web and fabric quality have always been a major concern in the manufacture of nonwoven fabric.

The purpose of this study is to investigate the role of fiber crimp and other processing conditions on nonwoven fabric properties. This will involve possible interactions between fiber crimp, carding parameters, crimp retention and relate these to fabric properties and processability in nonwoven equipment.

For this purpose, nonwoven needle-punched fabrics were produced from PET fibers with different crimp levels, using different card machine parameters during web formation. The webs were then cross-laid and bonded by needle punching using different needling densities and the influence all of these parameters were investigated with respect to "fabric" properties like basis weight, tensile strength, compressibility, air permeability, and directional distribution of the fibers (ODF's) using image analysis.

The basis weight measurements were statistically analyzed and investigated. It is concluded that the fiber crimp, carding and needling density significantly contribute to the differences in the basis weight measurement and so do the various fiber to card interactions.

The tensile strength of various needled fabrics were investigated. The results have shown that the mechanical response mainly depends on the fiber orientation distribution and processing conditions. Fiber crimp and finish also influence the mechanical performance. Higher carding speeds produced a dominant MD oriented structure and the ODF explains the cross-lapping effect and also the crimp pullout during carding.

The air permeability measurements were largely dependent on the weight per unit area and thickness of the final needled fabrics. So the fiber crimp, the various carding and the needling density parameters have a decisive effect on the rate of airflow through the fabric.

A power function can be used to describe the fabric behavior under compressive loads. This function which is fit to experimental data delivers two fitting parameters that characterize the shape of the experimental load-thickness curve. The extracted characteristic compression parameters are being evaluated with respect to inherent fiber crimp characteristics and the various carding and needling machine parameters during nonwoven production.