Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging
A micromechanical concept of filler-induced stress-softening and hysteresis is established that describes the complex quasi-static deformation behavior of filler reinforced rubbers upon repeated stretching with increasing amplitude. It is based on a non-affine tube model of rubber elasticity and a d...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-06-01
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| Series: | Polymers |
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| Online Access: | https://www.mdpi.com/2073-4360/12/6/1350 |
| _version_ | 1797565266700271616 |
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| author | Jan Plagge Manfred Klüppel |
| author_facet | Jan Plagge Manfred Klüppel |
| author_sort | Jan Plagge |
| collection | DOAJ |
| description | A micromechanical concept of filler-induced stress-softening and hysteresis is established that describes the complex quasi-static deformation behavior of filler reinforced rubbers upon repeated stretching with increasing amplitude. It is based on a non-affine tube model of rubber elasticity and a distinct deformation and fracture mechanics of filler clusters in the stress field of the rubber matrix. For the description of the clusters we refer to a three-dimensional generalization of the Kantor–Webman model of flexible chain aggregates with distinct bending–twisting and tension deformation of bonds. The bending–twisting deformation dominates the elasticity of filler clusters in elastomers while the tension deformation is assumed to be mainly responsible for fracture. The cluster mechanics is described in detail in the theoretical section, whereby two different fracture criteria of filler–filler bonds are considered, denoted “monodisperse” and “hierarchical” bond fracture mechanism. Both concepts are compared in the experimental section, where stress–strain cycles of a series of ethylene–propylene–diene rubber (EPDM) composites with various thermo-oxidative aging histories are evaluated. It is found that the “hierarchical” bond fracture mechanism delivers better fits and more stable fitting parameters, though the evolution of fitting parameters with aging time is similar for both models. From the adaptations it is concluded that the crosslinking density remains almost constant, indicating that the sulfur bridges in EPDM networks are mono-sulfidic, and hence, quite stable—even at 130 °C aging temperature. The hardening of the composites with increasing aging time is mainly attributed to the relaxation of filler–filler bonds, which results in an increased stiffness and strength of the bonds. Finally, a frame-independent simplified version of the stress-softening model is proposed that allows for an easy implementation into numerical codes for fast FEM simulations |
| first_indexed | 2024-03-10T19:09:41Z |
| format | Article |
| id | doaj.art-f30eb8dd260b4177935ce3ef5d70b97d |
| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-03-10T19:09:41Z |
| publishDate | 2020-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Polymers |
| spelling | doaj.art-f30eb8dd260b4177935ce3ef5d70b97d2023-11-20T03:55:18ZengMDPI AGPolymers2073-43602020-06-01126135010.3390/polym12061350Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative AgingJan Plagge0Manfred Klüppel1Deutsches Institut für Kautschuktechnologie e. V., Eupener Str. 33, D-30519 Hannover, GermanyDeutsches Institut für Kautschuktechnologie e. V., Eupener Str. 33, D-30519 Hannover, GermanyA micromechanical concept of filler-induced stress-softening and hysteresis is established that describes the complex quasi-static deformation behavior of filler reinforced rubbers upon repeated stretching with increasing amplitude. It is based on a non-affine tube model of rubber elasticity and a distinct deformation and fracture mechanics of filler clusters in the stress field of the rubber matrix. For the description of the clusters we refer to a three-dimensional generalization of the Kantor–Webman model of flexible chain aggregates with distinct bending–twisting and tension deformation of bonds. The bending–twisting deformation dominates the elasticity of filler clusters in elastomers while the tension deformation is assumed to be mainly responsible for fracture. The cluster mechanics is described in detail in the theoretical section, whereby two different fracture criteria of filler–filler bonds are considered, denoted “monodisperse” and “hierarchical” bond fracture mechanism. Both concepts are compared in the experimental section, where stress–strain cycles of a series of ethylene–propylene–diene rubber (EPDM) composites with various thermo-oxidative aging histories are evaluated. It is found that the “hierarchical” bond fracture mechanism delivers better fits and more stable fitting parameters, though the evolution of fitting parameters with aging time is similar for both models. From the adaptations it is concluded that the crosslinking density remains almost constant, indicating that the sulfur bridges in EPDM networks are mono-sulfidic, and hence, quite stable—even at 130 °C aging temperature. The hardening of the composites with increasing aging time is mainly attributed to the relaxation of filler–filler bonds, which results in an increased stiffness and strength of the bonds. Finally, a frame-independent simplified version of the stress-softening model is proposed that allows for an easy implementation into numerical codes for fast FEM simulationshttps://www.mdpi.com/2073-4360/12/6/1350filled elastomersstress softeningfiller-induced hysteresiscluster mechanicsFEM simulation |
| spellingShingle | Jan Plagge Manfred Klüppel Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging Polymers filled elastomers stress softening filler-induced hysteresis cluster mechanics FEM simulation |
| title | Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging |
| title_full | Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging |
| title_fullStr | Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging |
| title_full_unstemmed | Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging |
| title_short | Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging |
| title_sort | micromechanics of stress softening and hysteresis of filler reinforced elastomers with applications to thermo oxidative aging |
| topic | filled elastomers stress softening filler-induced hysteresis cluster mechanics FEM simulation |
| url | https://www.mdpi.com/2073-4360/12/6/1350 |
| work_keys_str_mv | AT janplagge micromechanicsofstresssofteningandhysteresisoffillerreinforcedelastomerswithapplicationstothermooxidativeaging AT manfredkluppel micromechanicsofstresssofteningandhysteresisoffillerreinforcedelastomerswithapplicationstothermooxidativeaging |