Effect of CO2 Laser Irradiation in Spinline on Mechanical Properties of Poly(ethylene terephthlate) Fibers

Abstract

: In the melt spinning of high molecular weight poly(ethylene terephthalate), spinline immediately below the spinning nozzle was heated by irradiating the CO 2 laser with the intention of controlling the physical and mechanical properties of resultant fibers. In comparison with the fibers prepared without the laser irradiation, as-spun fibers obtained with laser irradiation showed higher elongation at break and higher tenacity. Higher elongation was attributed to lower tensile stress in the spinline caused by the increase of spinline temperature. Drawn fibers were produced from thus prepared as-spun fibers at various draw ratios. When the drawn fibers with similar elongation at break were compared, fibers prepared with the laser irradiation showed steeper increase in the stress-strain curve in the region of low strain, and showed higher tenacity as a result. On the whole, plot of the relation between tenacity and elongation at break of each fiber shifted toward higher tenacity and higher elongation in case of fibers prepared with the laser irradiation, indicating that the toughness of the fibers were improved. Numerical simulation of the melt spinning process incorporating the effect of laser irradiation suggested that temperature increase by the laser irradiation was at most about 70 degree in the spinning conditions adopted in this study. It was also confirmed that the heating of the spinline immediately below the spinneret led to steeper decrease of spinline diameter in the region near the spinneret, and reduction of strain rate and decrease of tensile stress in the region of lowered spinline temperature. These changes in the thinning behavior of the spinline were speculated to be the origin of the changes in the mechanical properties of laser irradiated fibers.

High-Strength PET Fibers Produced by Conjugated Melt Spinning and Laser Drawing

“…Like conjugated spinning, laser spinning is a melt structure control method to deform fibers at a temperature higher than ordinary spinning by laser irradiation heating of the fiber just under the spinneret (Masuda et al, 2004). They speculated that the number of tensioned molecular chains can be decreased by the laser spinning of PET (Masuda et al, 2010).…”

“…In the 1990s, methods to produce high-molecular-weight PET fibers were researched (Ito et al, 1990;Huang et al, 1994). In recent years, a number of methods have been investigated to produce highstrength fibers by controlling the melt structure during the melt spinning process (Kikutani et al, 1996;Radhakrishnan et al, 1997;Jeon et al, 1998;Takarada et al, 2001;Masuda et al, 2004;Nakata et al, 2004;Masuda et al, 2010). Among these methods, the conjugated melt spinning process is used in the present study (Radhakrishnan et al, 1997;Nakata et al, 2004).…”

Effect of the Control of Polymer Flow in the Vicinity of Spinning Nozzle on Mechanical Properties of Poly(ethylene terephthalate) Fibers

“…Details of the numerical analysis were already reported in the previous papers (Masuda et al 2004(Masuda et al , 2009. In this analysis, temperature increase of the spin-line by laser irradiation was incorporated to the energy balance equation as follows.…”

“…In the previous paper, we reported the effect of the irradiation of carbon dioxide laser to the spin-line immediately below the spinneret (Masuda et al, 2004). The maximum tensile strength of PET drawn fibers prepared from the laser-irradiated as-spun fibers reached 1.40 GPa (10 cN/dtex).…”

Fiber structure development in PS/PET sea-island conjugated fiber during continuous laser drawing

“…Thus, to obtain high-strength fibers, a homogeneous chain network structure should be formed by melt spinning, followed by drawing to a high draw ratio. The term "melt structure control" [4][5][6][7][8][9][10][11] refers to methods of producing a homogeneous chain network structure, and bicomponent melt spinning has been investigated as one process of melt structure control. 5,9,11 The bicomponent melt spinning process, in which two types of polymer are simultaneously extruded from a spinneret, produces a unique fiber structure that is substantially different from that of a melt spun homopolymer.…”