| The relationships between the properties of cotton rotor-spun yarn and HVI tested properties of China cotton fiber have been studied comprehensively .The structural mechanics of rotor-spun yarn differs from that of ring-spun yarn in three aspects, they are wrapped fibers, more hooked fibers, and the radial distribution of twists. With QUESTAR Hi-Scope Video Microscope System made in USA, the three-dimensional coordinates of traced fibers in rotor-spun yarn have been measured precisely, then the quadratic parabola model of radial distribution of twist has been revealed.In this thesis, the structural mechanics of rotor-spun yarn have been studied comprehensively based on the results of the structural mechanics of ring-spun yarn obtained by Hearle and Pan Ning.The relationships of some structural mechanics of the main body of rotor-spun yarn, such as yarn fiber-volume fraction, yarn helix angle, cohesion factor, fiber slippage ratio and length efficiency factor, etc., with twist and yarn radial position have been obtained.The data of HVI tested cotton fiber properties are quite stable, so as that the relationships between the properties of blended cotton and that of carded slivers can be expressed in term of transform ratio K _i with predicting error rate below 6.38%.The multiple correlation coefficients of the strength of 58.3tex and 18.22tex rotor-spun yarn with HVI tested properties of carded sliver are as high as 0.926 and 0.877 respectively.Six premium regression equations of relationships between cotton fiber HVI tested properties and the strength, Uster evenness, neps of 58.3tex and 18.22 tex rotor-spun yarns have been obtained based on the research of structural mechanics of rotor-spun yarn and the properties of carded sliver tested with HVI.Two cotton blending models of 58.3tex and 18.22tex pure cotton rotor-spun yarns have been made using linear programming methods. And these results can be used to guide the cotton blending work in mill.
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