Measurement of amorphous orientation in poly(ethylene terephthalate) fibers by X-ray diffraction and its significance

Abstract

ABSTRACT:The orientation of the noncrystalline (amorphous) phase in poly (ethylene terephthalate) fibers is analyzed by separating the amorphous scattering in the wideangle x-ray diffraction patterns into isotropic and anisotropic components. Two parameters are used to characterize the amorphous orientation-the fraction of the anisotropic component and its degree of orientation. The x-ray amorphous orientation parameters are compared with the sonic modulus and the birefringence values. Our results illustrate that the intrinsic birefringence of the amorphous phase is not ''intrinsic'' but depends on its density. The role of the oriented amorphous phase in determining the strength (tenacity) and the dimensional stability (shrinkage) of the fibers is discussed. We conclude that although amorphous orientation determines the shrinkage, other factors such as the connectivity between the amorphous phase and the crystalline regions play an important role in determining the tenacity of the fibers.

Effect of molecular orientation on the crystallization and melting behavior in poly(ethylene terephthalate)

“…The large increase in f am after crystallization that we find in our fibres is in agreement with that reported for other fibers [23]. The large increase in f am suggests that the transformation of the oriented amorphous phase with a f am R0.18 into crystals with a high degree of crystallite orientation (measured f c w0.96), enhances the orientation of the surrounding amorphous matrix.…”

“…We used the azimuthal intensity plots to calculate a second measure of amorphous orientation, the fraction of the oriented amorphous phase (F am ) as the ratio of the area of the amorphous peak above the base-line to the total amorphous area [20][21][22][23].…”

“…Each of these scans was used to obtain the height of the amorphous halo. This height was then used to generate I(f) plot, that was used to evaluate Df [21][22][23].…”

Effects of annealing on structure and properties of TLCP/PEN/PET ternary blend fibers

“…Generally, shrinkage behavior was related to polymeric structure, and shrinkage was a non-recoverable deformation, which was attributed to the relaxation of oriented molecules in the amorphous regions. [31][32][33] Thermal shrinkage resulted from the relaxation of oriented amorphous phase into the more random state, and resulted in the removal of residual stresses formed during processing. 28 The amorphous region and crystallinity played dominant roles in the shrinkage behavior.…”

Structure evolution and mechanical behavior of poly(ethylene terephthalate) fibers drawn at different number of drawing stages

“…It has been claimed that tenacity is affected by the interlamellar tie molecules [46][47][48]. It has been claimed that tenacity is affected by the interlamellar tie molecules [46][47][48].…”