In well-bonded thermal point-bonded nonwovens, most failures originate at the bond edge. Although there have been many explanations of this observation, to date there has not been an experimental test of these explanations. This paper discusses the use of Raman microspectroscopy to infer the morphology of the polymer in the vicinity of the bond edge. The results show that there is a rapid loss of molecular orientation moving from the bridging fibers into the bond. This loss of orientation leads to a decrease in both the modulus and the strength of the fibers at the bond edge, thus explaining the observed failures. It is also shown that the loss of orientation in the vicinity of the bond edge depends directly on processing conditions.
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