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

Abstract

The effect of draw ratio, molecular weight, and sea-island conjugated spinning with a polystyrene component on the fiber structure development of PET during laser drawing was analyzed by in-situ measurements with a 0.1 ms time resolution using an ultra-high luminance X-ray beam generated from a synchrotron equipped with an undulator. The fiber temperature increased from 120 o C to 160-220 o C during the structure development process. By drawing the higher molecular weight PET to a higher draw ratio, a larger amount of fibrillar smectic mesophase formed just after the onset of necking, and a more highly oriented crystal formed after the extinction of the smectic mesophase. Accordingly, fibers with higher strength and higher thermal shrinkage stress were obtained. On the other hand, by conjugated spinning with a PS component, the fiber temperature increased along with an increase in the drawing stress, but the stress applied to the PET component should have decreased.The amount of smectic mesophase formed by the conjugated-spinning process was drastically decreased, and no crystallization induction time was observed, unlike the other cases. Crystallization, particularly the growth of a lamellar crystal, was also promoted. Moreover, a higher Young's modulus, a higher yield stress, and a higher shrinkage stress were observed for the conjugated-spun and drawn fibers. Therefore, the fibrillar smectic mesophase seems to block the formation of the lamellar crystal. Furthermore, the resultant fibrillar structure tends to result in a higher strength, but a relatively lower modulus and yield strength of the fiber.

Morphology Development of Polymer Blend Fibers along Spinning Line

“…The melting and mixing process can generate morphologies ranging from dispersed drops to fibers to lamella to co-continuous structures [33], see Figure 2. The initial morphology of immiscible polymer blend fibers is usually represented as a droplet-matrix or fibril-matrix morphology [31,32,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. The strategy to produce lamellae and other morphologies is more difficult than that required for the droplet-matrix morphology since the interfacial tension tends to minimize the surface of the second phase [7].…”

Effect of melt spinning conditions on the fiber structure development of polyethylene terephthalate

“…The average position of the necking point and its fluctuation width were determined by analysis of still images taken from the video movie recorded during each measurement. The resolution time was calculated by a reported method [18] by the position resolution, which was calculated from the fluctuation width of the necking point (0.09-0.20 mm), length of the necking point (0.12-0.31 mm), and width of the X-ray beam (0.05 mm). The obtained time resolution was 0.09-0.18 ms.…”

“…For PET/polystyrene (PS) conjugated spun fibers, no crystallization induction time was observed after drawing [18]. The authors suggested that the PET component did not bear the drawing stress;…”

“…There have been similar trials for producing high-strength fibers, collectively referred to as "melt structure control", which formed uniform molecular network structures by controlling the melt spinning process [2][3][4][5][6][7][8][9]. Fiber structure development after neck drawing has been observed for PET [10][11][12][13]18], polyethylene naphthalate (PEN) [14], polypropylene [15], polyphenylene sulfide [16], and polybutylene terephthalate (PBT) [17] in wide-angle X-ray diffraction (WAXD) and small-angle Xray scattering (SAXS) images captured with synchrotron X-rays at SPring-8. In particular, we previously analyzed the effect of the draw ratio on the fiber structure development of PET [10].…”

Preparation of high-performance microfiber synthetic leather base using thermoplastic polyurethane/sulfonated polysulfone electrospun nanofibers

“…However, in the postprocessing step for the MSLB, it is necessary to remove the sea component using toluene (unfigured sea-island fibers) or sodium hydroxide (figured sea-island fibers), which brings serious environmental pollution and waste of resources. 15 In contrast to the sea-island fibers, segmented pie fibers are usually split by mechanical treatment (needle punching, hydroentangling, ultrasonic, stretching) and have several advantages, such as high mechanical properties, being non-polluting and being easy to process; however, their nonwoven fabric still suffers from low permeability, poor tear resistance and hard softness, since the split fibers have relatively large diameter, filament structure and wedge cross-section, tending to pack tightly. To date, with the development of spinning technology, electrostatic spinning is considered as the most effective method for fabricating nanofibers with a diameter of <100 nm.…”