The kinetic model of pilling revisited

Abstract

The current paper revisits the simplified two step kinetic model of pilling and identifies an implicit assumption made by previous workers in the application of the model to experimental data. Relaxing this assumption potentially allows a paradigm shift in the understanding of the pilling process with quite different interpretations and conclusions drawn from the analysis of experimental pilling data. In the case of wool knitwear, the original implicit assumption is tested experimentally and found to be invalid. A reanalysis of the pilling behavior of wool knitwear reveals new insights into the process. First, the mass of fiber associated with pilling is approximately twenty times larger than previously thought and pilling is the primary mechanism associated with fiber loss during the pilling test, compared to Williams’ conclusion that pilling accounted for only approximately 4% of the mass loss. Secondly, the non-pillable fiber loss fraction is both relatively small and is limited to the early stages of the pilling test, indicative of this being associated with a relatively small percentage of fiber that is not securely held in the structure (e.g. perhaps predominately a short fiber fraction). More generally, this reinterpretation significantly changes the relative importance of the two conceptual steps in the pilling process and so gives new insights regarding likely beneficial approaches for managing pilling.