Nonwoven Fabric Strength and Orientation Analysis

This question examines the properties of cross-laid needlepunched nonwoven fabrics, specifically concerning tensile strength and fiber orientation.

Assertion [a] Analysis: Tensile Strength

The assertion states that cross-laid needlepunched nonwoven fabrics have higher tensile strength in the machine direction (MD). Cross-laid fabrics are constructed by laying webs of fibers sequentially, often alternating directions (e.g., MD and cross-machine direction, CD). Needle-punching entangles these fibers, enhancing overall strength. However, the strength distribution between MD and CD in cross-laid fabrics depends significantly on the specific lay angles and the relative number of fibers oriented in each direction. It is not a universal rule that MD tensile strength is higher; often, the goal is balanced strength, or the strength might be anisotropic without a specific bias towards MD. Therefore, the assertion is generally considered incorrect.

Reason [r] Analysis: Fiber Orientation

The reason claims that in cross-laid nonwoven fabrics, the fibers are randomly oriented. This is inaccurate. The defining characteristic of a cross-laid structure is the intentional, non-random orientation of fibers in distinct, usually alternating, directions. While entanglement occurs, the primary structure involves directional fiber placement. Randomly oriented fibers are characteristic of 'random laid' nonwovens, not 'cross-laid' ones. Thus, the reason is factually wrong.

Conclusion

Based on the analysis:

• Assertion [a] is incorrect because higher MD tensile strength is not a guaranteed characteristic of all cross-laid nonwovens.
• Reason [r] is incorrect because cross-laid fabrics feature directional fiber orientation, not random orientation.

Both the assertion and the reason are wrong.