Investigations on hygrothermal aging of thermoplastic polyurethane material

Boubakri, A.; Elleuch, Khaled; Guermazi, Noamen; Ayedi, H.F.

doi:10.1016/j.matdes.2009.05.038

Cited by 133 publications

(81 citation statements)

References 36 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%

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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%

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) . For example, an in vitro study found that water absorption induced dimensional changes in numerous commercial mouth guard products, which had compositions similar to those of thermoplastic overlay orthodontic materials 35) .…”

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 particular, the TPUs, which are generally described as "bridging the gap between rubber and plastics", impart high elasticity combined with high abrasion resistance. That is why TPU is widely used in industry and consumer products [8]. Thermoplastic elastomers (TPEs) exhibit functional properties of conventional vulcanized rubber, yet can be processed on thermoplastic fabrication equipment.…”

Section: Introductionmentioning

confidence: 99%

Morphology and tensile properties of thermoplastic polyurethane-halloysite nanotube nanocomposites

Gaaz

Sulong²,

Akhtar

et al. 2015

Int. J. Automot. Mech. Eng.

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The high aspect ratio of nanoscale reinforcements enhances the tensile properties of a pure polymer matrix. Researchers have reported the morphology and tensile properties of thermoplastic polyurethane and halloysite nanotube (TPU-HNTs) nanocomposites, formed through compression moulding processes. Few researchers have reported on TPU-HNTs formed through injection moulding. Therefore, the present work investigates the tensile properties of TPU and HNT nanocomposites via injection moulding. TPU and HNTs were mixed using a brabender mixer with concentrations ranging from 1wt.% to 15wt.% and varying mixing parameters (i.e., mixing speed, mixing time, and mixing temperature). Tensile bars were injection moulded by varying the moulding parameters (i.e., injection temperature, injection time, and injection pressure). A significant increment of tensile strength was found at 1wt.% HNT reinforcement. TPU-HNT nanocomposite with 1wt.% reinforcement exhibited tensile strength of 24.3 MPa, which was higher than that of pure TPU. The Young's modulus of the TPU-15wt.% HNT nanocomposite was 21.5 MPa. Thus, TPU-HNT had improved mechanical properties, compared to pure TPU, due to the addition of a nanofiller.

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Investigations on hygrothermal aging of thermoplastic polyurethane material

Cited by 133 publications

References 36 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

Morphology and tensile properties of thermoplastic polyurethane-halloysite nanotube nanocomposites

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