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Multiscale modeling for the heterogeneous strength of biodegradable polyesters
journal contribution
posted on 2018-10-31, 11:36 authored by Taohong Zhang, Geyu Jin, Xiaoxiao Han, Yue Gao, Qingfeng Zeng, Binbin Hou, Dezheng ZhangA heterogeneous method of coupled multiscale strength model is presented in this paper for calculating the strength of medical polyesters such as polylactide (PLA), polyglycolide (PGA) and their copolymers during degradation by bulk erosion. The macroscopic device is discretized into an array of mesoscopic cells. A polymer chain is assumed to stay in one cell. With the polymer chain scission, it is found that the molecular weight, chain recrystallization induced by polymer chain scissions, and the cavities formation due to polymer cell collapse play different roles in the composition of mechanical strength of the polymer. Therefore, three types of strength phases were proposed to display the heterogeneous strength structures and to represent different strength contribution to polymers, which are amorphous phase, crystallinity phase and strength vacancy phase, respectively. The strength of the amorphous phase is related to the molecular weight; strength of the crystallinity phase is related to molecular weight and degree of crystallization; and the strength vacancy phase has negligible strength. The vacancy strength phase includes not only the cells with cavity status but also those with an amorphous status, but a molecular weight value below a threshold molecular weight. This heterogeneous strength model is coupled with micro chain scission, chain recrystallization and a macro oligomer diffusion equation to form a multiscale strength model which can simulate the strength phase evolution, cells status evolution, molecular weight, degree of crystallinity, weight loss and device strength during degradation. Different example cases are used to verify this model. The results demonstrate a good fit to experimental data.
Funding
This paper is sponsored by the National Study Abroad Fund of China and supported by The National Key Research and Development Program of China (2017YFB1002304).
History
School
- Mechanical, Electrical and Manufacturing Engineering
Published in
Journal of the Mechanical Behavior of Biomedical MaterialsVolume
90Pages
337-349Citation
ZHANG, T. ... et al, 2018. Multiscale modeling for the heterogeneous strength of biodegradable polyesters. Journal of the Mechanical Behavior of Biomedical Materials, 90, pp.337-349.Publisher
© ElsevierVersion
- AM (Accepted Manuscript)
Publisher statement
This paper was accepted for publication in the journal Journal of the Mechanical Behavior of Biomedical Materials and the definitive published version is available at https://doi.org/10.1016/j.jmbbm.2018.10.018Acceptance date
2018-10-09Publication date
2018-10-19Copyright date
2019ISSN
1751-6161Publisher version
Language
- en