Abstract
A method is presented which permits the quantitative characterization of bonding strength in non-woven fabrics using loss tangent, tan δ, data measured directly from samples non-destructively with the Vibron DDV-II Viscoelastometer. The procedure is derived from a phenomenological model of the structure's mechanical behavior in which its energy dissipation capacity consists of both filament internal viscous friction and a filament-to-filament coulomb friction mechanism. By treating the coulomb dissipation in terms of an additional effective viscous component the loss tangent of the model representing the structure can be analytically expressed in terms of the internal filament viscous properties, a fiber to fiber coulomb parameter, and an undetermined assembly dispersion factor which is representative of bond strength. By measuring effective loss tangent data for the structure and a constituent filament at two separate frequencies and considering the magnitude of the coulomb mechanism to be independent of the test frequency in the range employed, both the assembly dispersion factor and the coulomb friction dissipation can be quantified. Using this procedure, loss tangent data from tests on a series of non-woven fabrics are used to calculate both assembly dispersion and interfilament coulomb friction factors. The value and significance of the calculated results are considered and discussed in terms of the mechanical behavior of the structures.
