Development of high-strength poly(ethylene terephthalate) fibers: An attempt from semiflexible chain polymer

Abstract

Poly(ethylene terephthalate) (PET) dominates the market of synthetic fibers because of its good performance and low cost; however, maximum strength of PET fibers available in the market remains at a low level. Based on such background, a project for the development of high-strength PET fibers was started in 2001 gathering researchers from major fiber companies and universities. Concept of the melt structure control was introduced and intense effort was made for the preparation of undrawn fibers which possess high potential for becoming high mechanical performance fibers after applying the drawing and annealing processes. It was found that the reduction of Deborah number in the melt spinning process by irradiating carbon dioxide laser to the spin-line and also by the use of a spinning nozzle of small diameter was found to be effective for the improvement of mechanical properties. To clarify the mechanism for such behavior, theoretical analysis was applied combining the numerical simulations for the spin-line dynamics and the coarse molecular dynamics to estimate the change in the state of molecular entanglement. Reduction of Deborah number in the melt spinning process was found to yield homogeneous entanglement structure with narrow distribution of molecular weight between adjacent entanglement points.