Anisotropy is evaluated for in-plane mechanical properties, such as tensile modulus, maximum stress in tension, elongation at maximum stress, shear modulus, and bending rigidity, of three designed sets of spot-bonded nonwoven fabrics. Image analysis is used to quantify the fiber orientation distribution and identify failure mechanisms. The non-woven fabrics in this study have been produced specifically to explore the effects of different processing conditions (temperature, pressure, and bond area) on mechanical performance. The results show that, within a typical window of processing conditions, bond area and bonding temperature have a significant influence on all the mechanical properties. The data also suggest that failure of thermally bonded nonwoven structures is likely to be governed by critical stress-based criteria. An important inference from this work is the recognition that the mechanical properties of thermally spot-bonded nonwoven structures can be described quantitatively through a simple composite model. The results also suggest that the azimuthal properties of the bonded and nonbonded regions, and thus the nonwoven, are likely to be amenable to continuum models of materials with ortho-tropic symmetry.

Current efforts to establish links between processing conditions and the structure and properties of nonwoven fabrics in general, and for point-bonded (spot-bonded) nonwovens in particular, would be served significantly by in situ experimental visualization and measurement of the structural changes that occur during controlled deformation experiments. The features of a simultaneous “tensile testing/image acquisition” instrument that can serve this critical need are described in this report. The instrument is effective in providing quantitative measures of the orientation distribution function (ODF) of the fibers, the bond spot strain, the unit bond repeat pattern strain, and the shear deformation of this unit cell as a function of applied macroscopic deformation. It is also useful in determining the failure mode as a function of the method of applying deformation to the nonwoven fabric. These features are exemplified through analysis of a point-bonded carded nonwoven, which is anisotropic in its fiber orientation distribution and in the geometry and distribution of its patterned thermal bond spots.

This paper describes a cylindrical lighting system and its applications for objectively assessing fabric pilling. This cylindrical lighting system allows easy isolation and measurement of pills by illuminating only the pills and suppressing the background. Using this new lighting scheme, the pilling properties in two knitted fabrics are successfully explored as a function of fiber type and abrasion cycles.

We recently reported on various techniques we have developed for accurate characterization appearance changes brought about by scratch and mar damage. Scratch and mar resistance is related to the ability of a coating to resist deformation. The appearance change is brought about by the scratches and by roughening, which in turn leads to a reduction in gloss and reflectivity. Marring can be minimized by the appropriate use of the wipe material employed. This paper reports on three common wipes used by the automotive industry and focuses on the measurement of the appearance of coating by image analysis.

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