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Thermo-Mechanical Chain Branching of Commercial High Density Polyethylene during Extrusion

Received: 17 August 2014    Accepted: 25 August 2014    Published: 20 September 2014
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Abstract

Two different phenomena may affect average molecular weight (Mw) of molten polyethylene during extrusion process. The first is crosslinking, which can be divided to two categories of chain branching and network formation, leading to an increase in Mw. The second is chain scission which leads to a decrease in the average Mw. In this work, chain branching of molten stabilized pipe grade high density polyethylene (HDPE) and unstabilized one, extruded in industrial twin screw extruder, has been studied. Therefore a series of analytical techniques including melt flow rate (MFR), capillary rheometer, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR) were employed. The unstabilized samples' MFR were lower than stabilized ones' which showed a higher melt viscosity of unstabilized samples due to their higher Mw. By applying rheometry test in different modes, the unstabilized PE samples showed a higher shear viscosity in comparison with stabilized ones agreeing with MFR results. DSC results showed a difference in degree of crystallinity between samples. This difference was verified by DMA result of solid state which showed a higher shear storage modulus for stabilized samples. Also, DMA results confirmed the obtained results from rheometry test in melt state. Additionally, FTIR results of stabilized and unstabilized samples demonstrated the difference between their chemical structures. Although it seems that the level of chain branching in this grade of HDPE is low howover, all techniques' results are in a good agreement which makes the provided results and data reliable. Moreover, a combination of the applied methods in this work can be helpful to determine the validity and efficiency of antioxidants.

Published in International Journal of Materials Science and Applications (Volume 3, Issue 5)
DOI 10.11648/j.ijmsa.20140305.17
Page(s) 168-176
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Thermo-Mechanical Chain Branching, High Density Polyethylene, Extrusion, Antioxidant

References
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  • APA Style

    Yadollah Teymouri, Saeed Houshmandmoayed, Mohammad Adibfar, Reza Rashedi. (2014). Thermo-Mechanical Chain Branching of Commercial High Density Polyethylene during Extrusion. International Journal of Materials Science and Applications, 3(5), 168-176. https://doi.org/10.11648/j.ijmsa.20140305.17

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    ACS Style

    Yadollah Teymouri; Saeed Houshmandmoayed; Mohammad Adibfar; Reza Rashedi. Thermo-Mechanical Chain Branching of Commercial High Density Polyethylene during Extrusion. Int. J. Mater. Sci. Appl. 2014, 3(5), 168-176. doi: 10.11648/j.ijmsa.20140305.17

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    AMA Style

    Yadollah Teymouri, Saeed Houshmandmoayed, Mohammad Adibfar, Reza Rashedi. Thermo-Mechanical Chain Branching of Commercial High Density Polyethylene during Extrusion. Int J Mater Sci Appl. 2014;3(5):168-176. doi: 10.11648/j.ijmsa.20140305.17

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  • @article{10.11648/j.ijmsa.20140305.17,
      author = {Yadollah Teymouri and Saeed Houshmandmoayed and Mohammad Adibfar and Reza Rashedi},
      title = {Thermo-Mechanical Chain Branching of Commercial High Density Polyethylene during Extrusion},
      journal = {International Journal of Materials Science and Applications},
      volume = {3},
      number = {5},
      pages = {168-176},
      doi = {10.11648/j.ijmsa.20140305.17},
      url = {https://doi.org/10.11648/j.ijmsa.20140305.17},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijmsa.20140305.17},
      abstract = {Two different phenomena may affect average molecular weight (Mw) of molten polyethylene during extrusion process. The first is crosslinking, which can be divided to two categories of chain branching and network formation, leading to an increase in Mw. The second is chain scission which leads to a decrease in the average Mw. In this work, chain branching of molten stabilized pipe grade high density polyethylene (HDPE) and unstabilized one, extruded in industrial twin screw extruder, has been studied. Therefore a series of analytical techniques including melt flow rate (MFR), capillary rheometer, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR) were employed. The unstabilized samples' MFR were lower than stabilized ones' which showed a higher melt viscosity of unstabilized samples due to their higher Mw. By applying rheometry test in different modes, the unstabilized PE samples showed a higher shear viscosity in comparison with stabilized ones agreeing with MFR results. DSC results showed a difference in degree of crystallinity between samples. This difference was verified by DMA result of solid state which showed a higher shear storage modulus for stabilized samples. Also, DMA results confirmed the obtained results from rheometry test in melt state. Additionally, FTIR results of stabilized and unstabilized samples demonstrated the difference between their chemical structures. Although it seems that the level of chain branching in this grade of HDPE is low howover, all techniques' results are in a good agreement which makes the provided results and data reliable. Moreover, a combination of the applied methods in this work can be helpful to determine the validity and efficiency of antioxidants.},
     year = {2014}
    }
    

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  • TY  - JOUR
    T1  - Thermo-Mechanical Chain Branching of Commercial High Density Polyethylene during Extrusion
    AU  - Yadollah Teymouri
    AU  - Saeed Houshmandmoayed
    AU  - Mohammad Adibfar
    AU  - Reza Rashedi
    Y1  - 2014/09/20
    PY  - 2014
    N1  - https://doi.org/10.11648/j.ijmsa.20140305.17
    DO  - 10.11648/j.ijmsa.20140305.17
    T2  - International Journal of Materials Science and Applications
    JF  - International Journal of Materials Science and Applications
    JO  - International Journal of Materials Science and Applications
    SP  - 168
    EP  - 176
    PB  - Science Publishing Group
    SN  - 2327-2643
    UR  - https://doi.org/10.11648/j.ijmsa.20140305.17
    AB  - Two different phenomena may affect average molecular weight (Mw) of molten polyethylene during extrusion process. The first is crosslinking, which can be divided to two categories of chain branching and network formation, leading to an increase in Mw. The second is chain scission which leads to a decrease in the average Mw. In this work, chain branching of molten stabilized pipe grade high density polyethylene (HDPE) and unstabilized one, extruded in industrial twin screw extruder, has been studied. Therefore a series of analytical techniques including melt flow rate (MFR), capillary rheometer, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR) were employed. The unstabilized samples' MFR were lower than stabilized ones' which showed a higher melt viscosity of unstabilized samples due to their higher Mw. By applying rheometry test in different modes, the unstabilized PE samples showed a higher shear viscosity in comparison with stabilized ones agreeing with MFR results. DSC results showed a difference in degree of crystallinity between samples. This difference was verified by DMA result of solid state which showed a higher shear storage modulus for stabilized samples. Also, DMA results confirmed the obtained results from rheometry test in melt state. Additionally, FTIR results of stabilized and unstabilized samples demonstrated the difference between their chemical structures. Although it seems that the level of chain branching in this grade of HDPE is low howover, all techniques' results are in a good agreement which makes the provided results and data reliable. Moreover, a combination of the applied methods in this work can be helpful to determine the validity and efficiency of antioxidants.
    VL  - 3
    IS  - 5
    ER  - 

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Author Information
  • Polymer Faculty, Amir Kabir University of Technology, Hafez Ave, Tehran, Iran

  • Research and Development Center, Jam Petrochemical Company, South pars Special Economic Zone (Asalouyeh) Iran

  • Research and Development Center, Jam Petrochemical Company, South pars Special Economic Zone (Asalouyeh) Iran

  • Research and Development Center, Jam Petrochemical Company, South pars Special Economic Zone (Asalouyeh) Iran

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