Irradiation stability and thermomechanical properties of 3D-printed SiC

As one of the most popular 3D printed metamaterials, the auxetic structure with its tunable Poisson’s ratio has attracted huge amount of attention recently. In this study, we designed an auxetic shape-memory metamaterial, which showed designable buckling responses by using the thermomechanically coupled in-plane instability. The influence of viscoelasticity on in-plane moduli and Poisson’s ratios of shape-memory auxetic metamaterial was experimentally investigated. Based on the generalized Maxwell model and finite-element method, the buckling behaviors and their main influence factors were studied. The analytical results and experimental ones showed a good agreement. Thermomechanical properties of the printed metamaterials govern the temperature and strain rate-dependent buckling, and a controllable transition from the negative to positive Poisson’s ratio in the metamaterials can be achieved. Based on the shape memory effect, the buckled state and the Poisson’s ratio of the metamaterials can be tuned by programmed thermomechanical processes. This study provides a simple and efficient way to generate morphing structures using the designable buckling effect.

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Self-Complementary Multiple Hydrogen-Bonding Additives Enhance Thermomechanical Properties of 3D-Printed PMMA Structures

Macromolecules ◽

10.1021/acs.macromol.9b00546 ◽

2019 ◽

Vol 52 (15) ◽

pp. 5574-5582 ◽

Cited By ~ 5

Author(s):

Dayton P. Street ◽

William K. Ledford ◽

Abigail A. Allison ◽

Steven Patterson ◽

Deanna L. Pickel ◽

...

Keyword(s):

Hydrogen Bonding ◽

Thermomechanical Properties ◽

3D Printed ◽

Multiple Hydrogen Bonding

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

Progress in Orthodontics ◽

10.1186/s40510-021-00362-8 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Kazem Dalaie ◽

Seyyed Mostafa Fatemi ◽

Samin Ghaffari

Keyword(s):

Loss Factor ◽

Flexural Modulus ◽

Thermomechanical Properties ◽

Mechanical And Thermal Properties ◽

Distilled Water ◽

Significance Level ◽

Viscous Modulus ◽

Modulus Difference ◽

3D Printed

Abstract 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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3D printing of PLA and PMMA multilayered model polymers: an innovative approach for a better-controlled pellet multi-extrusion process

10.25518/esaform21.1024 ◽

2021 ◽

Author(s):

Mohamed Yousfi ◽

Ahmed Belhadj ◽

Khalid Lamnawar ◽

Abderrahim Maazouz

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Processing Parameters ◽

Extrusion Process ◽

Thermomechanical Properties ◽

Three Point Bending ◽

Short Beam ◽

Multilayered Systems ◽

Chamber Temperature ◽

3D Printed

The present work deals with the 3D printing of multimaterials based on PLA/PMMA multilayers directly obtained from pellets. This polymer pair was chosen for their miscibility at the melt state and synergistic properties (i.e., to improve and weather tune the temperature resistance, transparency and thermomechanical properties of their PLA-based materials). Thus, 3D-printed parts with repeating PMMA/PLA/PMMA layers in the Z building direction were successfully prepared in different numbers but maintaining the same composition. The main objective was to better understand the interface/interphase properties developed during this innovative processing. First, further physicochemical and dynamic thermomechanical characterizations were performed. Second, the effects of multi-extrusion 3D printing processing parameters on the thermal stability of PLA, PMMA and their printed specimens were analyzed by GPC. Then, the structuralrheological and mechanical properties of the multilayered systems were investigated in comparison to their equivalent blend. The effects of flow kinematics during extrusion as well as printing chamber temperature (PCT) and infill density (ID) were specifically studied and rationalized. The triggered interfaces were characterized by SEM and subjected to flexural and short-beam three-point bending experiments that proved their dramatic influence on the final mechanical properties. The ultimate aim of this study is to enable successful control of the interfaces/interphases obtained in these 3D-printed PLA/PMMA systems in comparison to other forming processes.

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