Effect of initial take-up speed on properties and structure of as-spun and drawn/heat-set poly(ethylene terephthalate) filaments

Abstract

ABSTRACT:The effect of initial take-up speed on the properties and structure of both as-spun and drawn/heat-set poly(ethylene terephthalate) filaments was characterized through measurements of birefringence, percent crystallinity, tensile properties, high temperature shrinkage, loss tangent temperature dependence, DSC melting behavior, and wide-angle (WAXS) and small-angle X-ray scattering (SAXS). While a steady trend toward improved as-spun filament orientation and tensile properties occurred with increasing initial take-up speed, the reduced drawability of these more structured precursor filaments resulted in corresponding drawn/heat-set filaments that were of relatively lower overall orientation and tensile strength. The observed trends in tenacity, initial modulus, and high temperature shrinkage of the drawn/heat-set filaments appeared to be well correlated with the extent and distribution of amorphous phase rigidity as perceived through inferences made from the loss tangent temperature dependence. The WAXS patterns of the drawn/heat-set samples indicated that these filaments all possess a well-developed and highly oriented crystalline structure. Application of a simple two phase model allowed the determination of an amorphous orientation factor, which for the drawn/heat-set filaments was generally found to decrease as the draw ratio imposed in order to achieve comparable levels of elongation to break decreased. The SAXS patterns of the drawn/heat-set filaments indicated that comparable long period spacings exist in all cases and that a transition from a four-point pattern to a two-point bar-shaped pattern occurred when the precursor filament possessed some significant amount of as-spun crystallinity.

Interactions between Crystalline and Amorphous Domains in Semicrystalline Polymers: Small-Angle X-ray Scattering Studies of the Brill Transition in Nylon 6,6

“…Studies of nylon, polyethylene, and poly(ethylene terephthalate) fibers have shown that orientation and other characteristics of the noncrystalline or amorphous phase also influence the polymer performance. [1][2][3][4][5][6][7][8] In addition, interactions between the crystalline and amorphous regions are also expected to significantly affect the polymer properties. [6][7][8][9][10][11][12][13] Connectivity between the crystalline stems and the amorphous chain segments is often invoked to explain the correlation between lamellar spacings and unit cell dimensions 14 and the decrease in the unit cell volume of the crystals within the lamellae as the amorphous regions swell when exposed to moisture.…”

Improving mechanical properties of melt‐spun polyetherimide monofilaments by thermal drawing

“…Meanwhile, the tenacity and max force increased with the cooling temperature till 150 C, and then decreased rapidly at 200 C. Polymer filaments, when pulled above their glass transition temperature, straightens, and the polymer structure turns more crystalline, resulting in a decrease in their linear density. 20,23 R1 and R2, set at 220 C, is above the glass transition temperature of the polymer and hence deforms the polymer structure of the filament. The eventual structure of the polymer is dictated by the cooling temperature in R3 and R4.…”

“…The pattern consists of only rings and is devoid of any dots, indicating that the filament is amorphous. 20 The mechanical properties of PEI filaments were analyzed by estimating their tensile strength (Figure 2e). The as-spun PEI filament was found to possess a linear density of 74.08 den and a yield strength of 1.41 cN/den at 7.9% strain.…”

“…Figure 2d (inset) shows the WAXS pattern of the as‐spun filament. The pattern consists of only rings and is devoid of any dots, indicating that the filament is amorphous 20 …”