Wool/PET Composite Yarns And Their Fabrics

Wool/PET Sirofil and Plyfil composite yarns were consisted of PET filament and strand of Wool/PET staple fibers or single yarns in the modified spinning machine or twister. For light worsted fabrics, these methods are one of excellent ways to solve the problems caused by both raw materials and their workability. The differences of properties between components of composite yarns and the difference of structures between composite yarns and convitional two-ply yarns significantly affect the composite yarn properties and their fabric properties. So it will be useful to produce high quality light worsted fabrics made by composite yarns that a deepgoing and systematic study on the composite yarns. In this thesis, the author has worked on a practicing investigation and theoretical study on the processing technology, the forming yarn structures, and the mechanical properties of composite yarns and properties of their fabrics.The forming yarn structures depend on their spinning methods and the yarn structures and their fiber properties determine the yarn properties. The spacing between filament and strand of staple fibers and filament tension during spinning has an important effect on the Sirofil yarn structures and its properties. The tension between filament and staple fiber yarns during plying process also affects the Plyfil yarn structures and theirs properties. The cross-section of Sirofil composite yarns presents circular shape in which the filament and staple fibers separate two parts. From the cross-section and longitudinal view of Sirofil composite yarn, it can be seen that Sirofil composite yarn is similar to single spun yarn structure and, at the same time, similar to the helical geometry line of the two-ply yarn. Plyfil composite yarns is similar to two-ply yarn structures.For the mechanical properties of composite yarn, this thesis mainly has studied the tensile, bending and torsional properties and torque-relaxation behavior of Wool/PET composite yarns. The tensile properties of composite yarns mainly depend on the tensile properties of filament, and their tenacity is higher than that of two-fold Wool/PET staple fiber yarns. The difference of the tenacity and breaking extension between Sirofil and Plyfil composite yarns is not significant. The bending rigidity of Sirofil or Plyfil composite yarns is lower than that of two-fold staple fiber yarns.The author first theoretically analyses and calculated the tensile characteristic of Plyfil composite yarn by using a stress-analysis method and then got the formula of stress-strain of Wool/PET Plyfil composite yarn. The predicted results obtained by calculation are approximately agreement on the experimental results.Wool/PET composite yarns show higher residual torque than hat of conventional twofold staple yarns. In order to solve this problem, the author has worked on theoretical analysis...