A theoretical model of concurrent longitudinal and circumferential superdrawing of hollow polyethylene terephthalate fibers

• Published in: Polymer engineering and science Vol. 50; no. 9; pp. 1773 - 1779
• Main Authors: Wang, Youjiang, Aneja, Arun Pal
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.09.2010; Wiley; Society of Plastics Engineers, Inc; Blackwell Publishing Ltd
• Subjects: Applied sciences; Chemical processes; Circumferences; Composition; Crystallization; Cylinders; Elongation; Exact sciences and technology; Fibers; Fibers and threads; Forms of application and semi-finished materials; Internal pressure; Mathematical models; Mechanical properties; Melt spinning; Polyethylene; Polyethylene terephthalate; Polyethylene terephthalates; Polymer industry, paints, wood; Production processes; Technology of polymers; Textile fibers, Synthetic; Viscoelasticity; United States; Ethylene terephthalate polymer; Viscoelasticity; Experimental test; Ester polymer; Synthetic fiber; Theoretical study; Mechanical properties; Melt spinning; Property processing relationship; Modeling; Hot drawing; Hollow fiber; Diameter; Rheological properties
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.21711

In a superdrawing process, a polyethylene terephthalate (PET) filament is elongated without developing much orientation and crystallization. Exploiting this phenomenon may bring about lower cost, more flexible and faster response in synthetic fiber production. The concurrent longitudinal and circumferential superdrawing phenomenon of PET hollow fibers is explained using the viscoelastic behavior of a thick walled cylinder under an internal pressure and an axial load in a continuous process. The model defines the stress–strain‐displacement relationship of hollow fibers. The fiber undergoes instantaneous radial superdrawing (increase in thickness) in the process zone followed by concurrent circumferential (increase in void) and longitudinal (increase in length) superdrawing. Based on material viscoelastic properties and processing conditions, the model predicts the threadline tension, internal pressure, and final fiber geometries. Excellent agreement of the model with experimental results is observed over a range of processing conditions. The model is developed from a process engineering viewpoint to enable the analysis of the impact of process parameters during superdrawing on fiber properties. POLYM. ENG. SCI., 50:1773–1779, 2010. © 2010 Society of Plastics Engineers