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Effect of chain branching on the rheological properties of HDPE/LLDPE and HDPE/LDPE blends under shear and elongational flows and evaluation of die swell and flow instabilities

  • Daniel Muller Gomes de Freitas , Milena Heloísa Araújo Silva , Shirley Nóbrega Cavalcanti , Rafael Braga da Cunha EMAIL logo , Pankaj Agrawal , Gustavo de Figueiredo Brito and Tomás Jeferson Alves de Mélo EMAIL logo
Published/Copyright: March 24, 2025
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International Polymer Processing
From the journal International Polymer Processing Volume 40 Issue 2

Abstract

Depending on the conditions of polymer synthesis, polyethylene can exhibit various molecular structures, such as long and short-chain branching, which influence its molecular weight and molecular weight distribution. The molecular structure of polyethylene in the blend significantly impacts its properties, making it essential to study these effects on the blend’s final properties. Based on the above, this work aims to investigate the effects of 1-hexene short chain branching (SCB) of linear low-density polyethylene (LLDPE) and long chain branching (LCB) of low-density polyethylene (LDPE) polymers on the rheological properties and processing of blends with high-density polyethylene (HDPE). LDPE showed higher complex viscosity at low frequencies and stronger shear thinning behavior than HDPE and LLDPE-H polymers. The strong shear thinning behavior of LDPE may be related to its higher molecular weight and presence of LCB. Capillary rheometry tests demonstrated a shear-thinning behavior for both the pure polymers and the blends, with the results for the blends being lower than those for the pure polymers, following the direct mixing rule. LDPE exhibited lower viscosity compared to HDPE, LLDPE-H, and all the blends, corroborating the observed results in complex viscosity at high deformation values. As for the flow instabilities, the occurrence of these instabilities at high shear rates was observed for all the polymers investigated in this study. Two methods were used to measure the swell of the extrudate (in-line and off-line), and both methods were efficient in describing the swell behavior as a function of shear rate. The elongational viscosity of the LDPE was found to exhibit “strain hardening” behavior, i.e., an increase in elongational viscosity with increasing strain and time.

Keywords: polyethylene; chain branching; polymer blends; shear and elongational flows; flow instabilities
Corresponding authors: Rafael Braga da Cunha and Tomás Jeferson Alves de Mélo, Department of Materials Engineering, Federal University of Campina Grande (UFCG), Campina Grande, Paraiba, 58429-900, Brazil, E-mail: (R.B. da Cunha), (T.J.A. de Mélo).

Funding source: CAPES and CNPq

Award Identifier / Grant number: TJAM—Grant Numbers 577061/20089/Jovens Pesquisadores-Nanotecnologia, 483743/20119/UNIVERSAL and 426191/20161/UNIVERSAL

Acknowledgments

The authors thank CAPES and CNPq (TJAM – Grant Numbers: 577061/20089/Jovens Pesquisadores-Nanotecnologia, 483743/20119/UNIVERSAL and 426191/20161/UNIVERSAL) for financial support.

  1. Research ethics: Not applicable.

  2. Informed consent: Not applicable.

  3. Author contributions: Daniel Muller: formal analysis (equal); resources (equal); supervision (equal); writing – review and editing (equal). Milena Heloísa: formal analysis (equal); resources (equal); supervision (equal); writing – review and editing (equal). Shirley N. Cavalcanti: methodology (supporting); software (equal). Rafael Braga da Cunha: investigation (equal); methodology (supporting); software (equal); validation (equal). Pankaj Agrawal: methodology (equal); supervision (equal). writing – original draft (equal); writing – review and editing (equal). Gustavo de Figueiredo Brito: conceptualization (equal); methodology (equal); supervision (equal); Tomas Jeferson Alves de Mélo: resources (equal); supervision (equal); writing – review and editing (equal). The authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  4. Use of Large Language Models, AI and Machine Learning Tools: None declared.

  5. Conflict of interest: The authors declare that there are no conflicts of interest.

  6. Research funding: Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq (TJAM – Grant Numbers: 577061/20089, 483743/20119/UNIVERSAL and 426191/20161).

  7. Data availability: Not applicable.

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Received: 2024-08-30
Accepted: 2025-02-15
Published Online: 2025-03-24
Published in Print: 2025-05-26

© 2025 Walter de Gruyter GmbH, Berlin/Boston

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https://doi.org/10.1515/ipp-2024-0115
Keywords for this article
polyethylene; chain branching; polymer blends; shear and elongational flows; flow instabilities

Articles in the same Issue

  1. Frontmatter
  2. Review Article
  3. Corrosion resistive conducting polymeric nanocomposite-based coatings on steel: a mechanistic insight
  4. Research Articles
  5. Effect of compatibilizer type on the properties of thermoplastic elastomers based on recycled polyethylene at high ground tire rubber content
  6. Analyzing the effects of solid fraction and heat treatment on the mechanical properties of 3D printed polymer lattices
  7. Effect of polyvinyl acetate on the properties of biodegradable thermoplastic starch/polyethylene glycol blends
  8. A color masterbatch assistance system for optimizing product color by masterbatch addition in injection molding of post-industrial recyclates
  9. Enhancing 3D printing with composite filaments incorporating electronic waste: a study on flexural and compression strength
  10. Development of enhanced co-continuous PVDF/PET nanocomposites via synergistic effects of graphite particle size, hybrid systems, and reduced graphene oxide
  11. Integration of nanographene and action of fiber sequences on functional behaviour of composite laminates
  12. Effect of chain branching on the rheological properties of HDPE/LLDPE and HDPE/LDPE blends under shear and elongational flows and evaluation of die swell and flow instabilities
  13. Effect of graphene nanoplatelets (GnPs) on low velocity impact properties of hybrid kevlar/basalt fiber reinforced epoxy based composites
  14. Sustainability in rotational molding: a study on recycling and the influence of additives
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