Nonlinear time-dependent behavior of rheodictic polymers : a theoretical and experimental investigation

Oseli, Alen (author), Mihelčič, Mohor (author), Šobak, Matic (author), Slemenik Perše, Lidija (author)

The present study examined the nonlinear time-dependent behavior of rheodictic polymers, a class of noncrosslinked materials that exhibit flow. Such behavior was addressed with extended Schapery’s nonlinear viscoelastic model by introducing new physical quantities, i.e., the flow term Φ$_{flow}$ and corresponding nonlinear shift parameter g$_{2,flow}$. While Φ$_{flow}$ portrays irrecoverable deformation, g$_{2,flow}$ depicts a nonlinear contribution to flow acceleration. This theory was accompanied by analytical and experimental methodologies for identifying all the parameters in the linear and nonlinear viscoelastic domains. Predictions of long-term time-dependent behavior (in shear) at various stress states show excellent agreement with the experimental data, i.e., within 5% error, obtained for polycarbonate at 130 °C. Surprisingly, the newly introduced g$_{2,flow}$ indicates that flow retardation occurs with increasing stress, implying that a highly deformed entangled system hinders molecular reptation/disentanglement. Nevertheless, the proposed extension of Schapery’s nonlinear viscoelastic model not only allows accurate predictions of the nonlinear time-dependent behavior of rheodictic polymers but also enables a detailed outlook on the underlying molecular mechanisms under severe environmental and loading conditions.

• Language: English
• Keywords: rheodictic polymers, nonlinear behavior, time-dependent mechanical properties, creep process, Schapery’s nonlinear model
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 11 str.
• Numbering: Vol. 137, art. 108535
• PID: 20.500.12556/RUL-159934
• UDC: 620.17:678.7
• ISSN on article: 1873-2348
• DOI: 10.1016/j.polymertesting.2024.108535
• COBISS.SI-ID: 203185923
• Publication date in RUL: 31.07.2024

Record is a part of a journal

• Title: Polymer testing
• Publisher: Elsevier
• ISSN: 1873-2348
• COBISS.SI-ID: 23025669

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: reodiktični polimeri, nelinearno vedenje, časovno odvisne mehanske lastnosti, proces lezenja, Schaperijev nelinearni model