The structure of polyester/cotton blended air-jet spun yarn

We investigate the differences in the structure of polyester and cotton wrappers, thus gaining some idea of their wrapper-fiber-forming tendencies. We observe and photograph forty randomly selected locations along a yarn length with a scanning electron microscope to determine the numbers of polyester and cotton wrappers, the numbers of loose polyester and cotton wrappers, and the wrapping angle for each wrapping fiber. We also study the effects of polyester length, denier, cotton fiber type, and yam delivery speed on these parameters. We investigate the possibility of nep formation in ah-jet spinning by studying the structure of neps with the scanning electron microscope. The results show that though polyester fibers contribute more to the total number of wrappers, cotton seems to have better wrapper-forming tendencies when the numbers of polyester and cotton wrappers are expressed as percents of the respective numbers of fibers in the yam cross sections. Cotton forms more loose wrappers than polyester, and the wrapping angle for cotton is greater. The structural study of neps collected from air-jet spun yarns shows that some of them have probably formed during spinning.