Structural formation of amorphous poly(ethylene terephthalate) during uniaxial deformation above glass temperature

Online wide‐angle X‐ray diffraction/small‐angle X‐ray scattering measurements for the CO2‐laser‐heated drawing of poly(ethylene terephthalate) fiber

“…This indicates that only a part of amorphous phase is highly oriented. This scattering should be the same as that observed for PET film by Mahendrasingam et al 20,[22][23][24] and Kawakami et al 31,32 Crystal diffraction appeared abruptly 20 ms after necking. It is not observed at all in the 17 ms diffraction image, and becomes clear in the 30 ms image.…”

“…For the drawing process, most on-line measurement studies fall into one of two categories; batch drawing under small strain rate [20][21][22][23][24][25][26][27][28][29][30][31][32] , and draw ratio dependence of continuous drawing [33][34][35][36] . In both cases, x-ray diffraction images are taken at a fixed position.…”

Structure evolution of PET under step-wise and continuous deformation modes: the effect of stress relaxation on the strain-induced morphology

“…The 2D-WAXS patterns treatment was adapted from the proposed by Kawakami at el. [2]. The two linear intensity profiles taken along the equatorial and meridional directions were used to estimate mass fractions of the three phases.…”

“…The availability of synchrotron X-ray radiation made possible to measure in-situ the structural formation of PET films and fibres in real time. Many studies were conducted to investigate the effect of processing conditions and modes of deformation below [1] and above [2,3] T g from glassy PET. During uniaxial deformation above T g of amorphous PET structural development consist of three stages, according to recent models [2,3]: i) molecular orientation occurs due to strong molecular interaction -"orientation" stage; ii) nucleus start to appear as a result of molecular orientation -"nucleation" stage; and iii) crystallization develops through a growth process -"growth" stage.…”

“…Many studies were conducted to investigate the effect of processing conditions and modes of deformation below [1] and above [2,3] T g from glassy PET. During uniaxial deformation above T g of amorphous PET structural development consist of three stages, according to recent models [2,3]: i) molecular orientation occurs due to strong molecular interaction -"orientation" stage; ii) nucleus start to appear as a result of molecular orientation -"nucleation" stage; and iii) crystallization develops through a growth process -"growth" stage. Three distinct PET morphologies are developed: i) an unoriented amorphous phase (isotropic); ii) a mesophase with a degree of packing order between the crystalline and the amorphous phase (anisotropic oriented amorphous phase); and iii) a crystalline phase [2,3].…”