Impact of aging conditions on mechanical properties of thermoplastic polyurethane

Boubakri, A.; Haddar, Nader; Elleuch, Khaled; Bienvenu, Yves

doi:10.1016/j.matdes.2010.04.023

Cited by 168 publications

(113 citation statements)

References 40 publications

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“…Specifically, at each selected time point, residual stress in the former environment was significantly lower than the latter (p<0.05; material type not included as a variable). These results confirm that a hygrothermal aging environment can accelerate stress relaxation of thermoplastic materials [18][19][20][21] .…”

Section: Resultssupporting

confidence: 78%

“…Bao et al 18) found that in bismaleimide resin, absorbed water accelerated the relaxation of the matrix through a process called plasticization. Boubakri et al 19,20) confirmed this irreversible phenomenon in thermoplastic polyurethane and pointed out that the nature of plasticization was increased mobility of chains' macromolecular segments. The authors believed that water absorption may induce a breakup of the intrachain and/or interchain hydrogen bonds and modify the free volume of the polymers.…”

Section: Discussionmentioning

confidence: 96%

“…On the other hand, thermal aging was found to increase mechanical properties like Young's modulus and the tensile stress of polymers. However, in a hygrothermal aging environment, temperature promoted water diffusion in polymers, therefore accelerating degradation 19) . In our study, significant differences between materials arises since 90 min in the atmospheric environment, whereas it is observed from the start in the 37°C-water-bath environment.…”

Section: Discussionmentioning

confidence: 99%

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Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

et al. 2013

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Mechanical properties are crucial for screening orthodontic thermoplastic materials for invisible aligners. However, most of previous studies were carried out within laboratory conditions which limit our understanding of the mechanical behaviors of aligners within oral environment. In this study, we studied the dynamic stress relaxation of thermoplastic materials by combination of Bose ElectroForce and a homemade temperature-controlled water bath. The 3-h stress relaxation curves of five orthodontic thermoplastic materials were measured within 37°C water bath as well as comparatively in ambient atmospheric environment (~20°C). The percentage residual stress at 0, 30, 60, 90, 120, 150, and 180 min was selected for statistical analyses. As expected, the experimental results showed that the residual stress within all five materials decreased with time, and that this process was significantly accelerated in the 37°C water bath (p<0.05). Compared with other materials, Erkodur and Masel exhibited slower relaxing rates in the 37°C water bath (p<0.05).

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Section: Resultssupporting

confidence: 78%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

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Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

et al. 2013

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“…Due to water absorption, several physicochemical changes take place in the material, causing the mechanical properties of the polymer to be irreversibly degraded [31][32][33] . Hence, moisture in any form is unfriendly for polymers as it often causes swelling and degradation 34) .…”

Section: Discussionmentioning

confidence: 99%

Preparation and characterization of thermoplastic materials for invisible orthodontics

Zhang

Bai

Ding

et al. 2011

Dental Materials Journal

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PETG/PC/TPU polymer blend was prepared by mechanical blending. The mechanical properties of modified PETG/PC/TPU blend were characterized using a universal testing machine, and results were compared against two commercial thermoplastic products -Erkodur and Biolon. Blending modification improved the properties of PETG/PC/TPU. When blending ratio (wt%) was 70/10/20, PETG/PC/TPU exhibited optimal mechanical properties which exceeded those of Erkodur and Biolon. Tear strength was 50.23 MPa and elongation at break was 155.99%. Stress relaxation rate was 0.0136 N/s after 1 hour, which was significantly slower than Erkodur and Biolon (p<0.05). Water absorption rate was 0.57% after 2 weeks, which was significantly lower than Erkodur and Biolon (p<0.05).

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“…In this context, thermoplastic polyurethane (TPU) is an interesting insulating matrix for developing flexible conductive Mt-PPy composites with high electrical conductivity at low percolation threshold. TPU is among the most versatile engineering thermoplastics since it associates the properties of thermoplastic polymers with those of vulcanized rubbers without vulcanizing agents [39,40]. Moreover, to the best of our knowledge, there are no studies concerning the preparation of TPU composites with Mt-PPy through melt blending method.…”

Section: Introductionmentioning

confidence: 99%

Novel electrically conductive polyurethane/montmorillonite-polypyrrole nanocomposites

Ramôa¹,

Barra²,

Merlini³

et al. 2015

Express Polym. Lett.

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Abstract. This work describes the production of electrically conductive nanocomposites based on thermoplastic polyurethane (TPU) filled with montmorillonite-dodecylbenzenesulfonic acid-doped polypyrrole (Mt-PPy.DBSA) prepared by melt blending in an internal mixer. The electrical conductivity, morphology as well as the rheological properties of TPU/MtPPy.DBSA nanocomposites were evaluated and compared with those of TPU nanocomposites containing different conductive fillers, such as polypyrrole doped with hydrochloride acid (PPy.Cl) or dodecylbenzenesulfonic acid (PPy.DBSA) or montmorillonite-hydrochloride acid-doped polypyrrole (Mt-PPy.Cl), prepared with the same procedure. The TPU/MtPPy.DBSA nanocomposites display a very sharp insulator-conductor transition and the electrical percolation threshold was about 10 wt% of Mt-PPy.DBSA, which was significantly lower than those found for TPU/Mt-PPy.Cl, TPU/PPy.Cl and TPU/PPy.DBSA. Morphological analysis highlights that Mt-PPy.DBSA filler was better distributed and dispersed in the TPU matrix, forming a denser conductive network when compared to Mt-PPy.Cl, PPy.Cl and PPy.DBSA fillers. This morphology can be attributed to the higher site-specific interaction between TPU matrix and Mt-PPy.DBSA. The present study demonstrated the potential use of Mt-PPy.DBSA as new promising conductive nanofiller to produce highly conductive polymer nanocomposites with functional properties.

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Impact of aging conditions on mechanical properties of thermoplastic polyurethane

Cited by 168 publications

References 40 publications

Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

Preparation and characterization of thermoplastic materials for invisible orthodontics

Novel electrically conductive polyurethane/montmorillonite-polypyrrole nanocomposites

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