Helical instability in film blowing process: Analogy to buckling instability

Joo Sung Lee, Ilyoung Kwon, Hyun Wook Jung, Jae Chun Hyun

    Research output: Contribution to journalArticlepeer-review

    7 Citations (Scopus)

    Abstract

    The film blowing process is one of the most important polymer processing operations, widely used for producing bi-axially oriented film products in a single-step process. Among the instabilities observed in this film blowing process, i.e., draw resonance and helical motion occurring on the inflated film bubble, the helical instability is a unique phenomenon portraying the snake-like undulation motion of the bubble, having the period on the order of few seconds. This helical instability in the film blowing process is commonly found at the process conditions of a high blow-up ratio with too low a freezeline position and/or too high extrusion temperature. In this study, employing an analogy to the buckling instability for falling viscous threads, the compressive force caused by the pressure difference between inside and outside of the film bubble is introduced into the simulation model along with the scaling law derived from the force balance between viscous force and centripetal force of the film bubble. The simulation using this model reveals a close agreement with the experimental results of the film blowing process of polyethylene polymers such as low density polyethylene and linear low density polyethylene.

    Original languageEnglish
    Article number121501
    JournalPhysics of Fluids
    Volume29
    Issue number12
    DOIs
    Publication statusPublished - 2017 Dec 1

    Bibliographical note

    Funding Information:
    This work was supported by the National Research Foundation of Korea (NRF) grant funded by theKorean government (MSIP) (No. NRF-2016R1A5A1009592) and the Ministry of Trade, Industry and Energy (MOTIE, Korea) under the Industrial Technology Innovation Program (No. 10067082).

    ASJC Scopus subject areas

    • Computational Mechanics
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering
    • Fluid Flow and Transfer Processes

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