Structure-process-property relationships in polyester spun yarns: The role of fiber friction

The research explored fiber-process-structure-property relationships in friction, bending, and tensile properties, hairiness and evenness of 100% polyester air-jet yarns. Eight different fiber samples with different spin finish type, spin finish level, fiber denier, and fiber length were used to produce yarn samples at 30 conditions using central composite design where first nozzle pressure, second nozzle pressure, main draft ratio, and spinning speed were varied at five levels.; A yarn structural scheme based on the crimpiness of core, wrapping angle, and hair characteristics of air-jet yarns was proposed and used to establish fiber-process-structure-property relationships.; Empirical models established for fiber-process-structure relationships in air-jet yarns explain the effects of fiber parameters and process parameters on the structure of yarns. Empirical models established for fiber-structure-property relationships and fiber-process-property relationships in air-jet yarns explain the effects of fiber parameters and structural parameters/process parameters on various yarn properties.; Roles of fiber parameters in determining the properties of air-jet yarns were explained by two effects: (i) effect of intrinsic fiber properties, and (ii) effect of changes in yarn structure resulting from changes in fiber properties. The relative importance of the two effects in determining yarn properties was identified; the effect of changes in yarn structure resulting from varying fiber properties (e.g., surface properties and bending properties) can have a greater effect than that of intrinsic fiber properties.; Yarn properties were simultaneously optimized using Derringer-Suich method which utilizes desirability function. A yarn friction model comprising the effects of bending force and elongation force was proposed.; Thus, the research has led to a better understanding of friction, bending, and tensile properties of air-jet yarns. Such an understanding is critical to the engineering of yarns with desired structural and physical properties.