Experimental characterization of the mechanical properties of PETG and PA6 thermoplastics

Salcedo, Milton Coba; Peñaloza, Carlos Acevedo; Gómez, Gustavo Guerrero

doi:10.12988/ces.2018.88369

Cited by 3 publications

(1 citation statement)

References 2 publications

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“…According to DSC, Tg of untreated aligner sheets was 76.3°C in Duran and 76.6°C in Erkodur. Furthermore, previously, this temperature was measured at about 80°C in pure PETG [24], 75.3°C in Duran [23], and 77.2°C in Erkodur [19], which are in line with the results of our study. In this study, the dynamic Tg evaluated by DMTA, significantly decreased after thermoforming and also thermocycling in both materials, indicating the attenuation of thermomechanical properties after these processes.…”

Section: Discussionsupporting

confidence: 93%

Dynamic mechanical and thermal properties of clear aligners after thermoforming and aging

2021

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Background Based on the role of properties of aligner materials on their efficiency, we aimed to assess their thermomechanical properties after thermoforming and simulated aging. Methods In this experimental study, 96 samples of polyethylene terephthalate glycol (PETG) aligners (Duran and Erkodur) were prepared and divided to three groups: control (C), after thermoforming (T), after thermoforming and aging (TA). Thermoforming was done through 3D-printed molds, and aging was exerted by 200 thermal cycles after immersion in 37°C distilled water for 24h. Flexural modulus, hardness, glass transition temperature (Tg), elastic and viscous modulus, and loss factor were evaluated. Two-way ANOVA, T-independent, and Tukey HSD tests were done for statistical analysis and significance level was set to 0.05. Results In both materials, flexural modulus decreased significantly after thermoforming, 88% in Duran and 70% in Erkodur, but did not change significantly after aging. After thermoforming, hardness decreased significantly in both materials (22% in Duran and 7.6% in Erkodur). Dynamic Tg was significantly lower in T and TA in both materials. At all temperatures (25, 37, 55°C) in Duran, the elastic modulus difference was only significant between C and TA, but in Erkodur, it decreased significantly in T, and there was no significant change after aging. Viscous modulus and loss factor showed the same change patterns at all temperatures. In both materials, they increased after thermoforming, but did not change significantly after aging. Conclusion Thermoforming had more prominent role than aging in diminishing of thermomechanical properties. In general, Duran had greater thermomechanical stability than Erkodur.

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Section: Discussionsupporting

confidence: 93%

Dynamic mechanical and thermal properties of clear aligners after thermoforming and aging

2021

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Miscibility and crystallization behavior of Poly(butylene terephthalate)/Poly(ethylene terephthalate-co-1,4-cyclohexylene dimethylene terephthalate) blends

Guo,

Luo,

et al. 2024

Polymer

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Physical and chemical changes of clear aligners after thermoforming and intraoral exposure

Dalaie,

Rafsanjan,

Nojehdehian

et al. 2024

APOS

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Objectives: This study assessed the physical and chemical changes of clear aligners after thermoforming and intraoral exposure. Material and Methods: This ex vivo study evaluated raw sheets, thermoformed sheets, and aligners used for 2 weeks from two commercial brands of Erkodur and Shinseki (n = 8 in each group). The surface hardness (by the Vickers hardness test), thickness (by a digital caliper), and glass transition temperature (Tg) (by differential scanning calorimetry) of the specimens were measured, and they underwent X-ray diffraction (XRD) to assess their degree of crystallinity and attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR) for analysis of their molecular composition. Data were analyzed by one-sample, paired and independent t-tests, and Mann–Whitney U and Wilcoxon signed-rank tests (alpha = 0.05). Results: The XRD and ATR-FTIR spectra of Erkodur and Shinseki aligners matched those of polyethylene terephthalate glycol polymer and did not change after thermoforming or intraoral exposure. Unlike intraoral exposure (P > 0.05), thermoforming significantly decreased the hardness of both brands of aligners (P < 0.05). Intraoral exposure significantly decreased the thickness of Erkodur aligners at some points and significantly increased the thickness of Shinseki aligners (P < 0.05). Thermoforming significantly decreased the Tg of both brands of aligners (P < 0.05). Intraoral exposure significantly decreased the Tg of Erkodur and increased the Tg of Shinseki aligners (P = 0.000). Conclusion: Erkodur and Shinseki aligners showed high chemical and structural stability after thermoforming and 2 weeks of intraoral exposure. However, thermoforming affected the thermal and physical properties of both brands of aligners. Erkodur aligners had higher dimensional stability than Shinseki aligners.

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Experimental characterization of the mechanical properties of PETG and PA6 thermoplastics

Cited by 3 publications

References 2 publications

Dynamic mechanical and thermal properties of clear aligners after thermoforming and aging

Dynamic mechanical and thermal properties of clear aligners after thermoforming and aging

Miscibility and crystallization behavior of Poly(butylene terephthalate)/Poly(ethylene terephthalate-co-1,4-cyclohexylene dimethylene terephthalate) blends

Physical and chemical changes of clear aligners after thermoforming and intraoral exposure

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