Optically transparent high temperature shape memory polymers

Soft Matter ◽  
2016 ◽  
Vol 12 (11) ◽  
pp. 2894-2900 ◽  
Author(s):  
Xinli Xiao ◽  
Xueying Qiu ◽  
Deyan Kong ◽  
Wenbo Zhang ◽  
Yanju Liu ◽  
...  
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Shape Memory Polymers ◽  
Optically Transparent

Optically transparent shape memory polyimide exhibiting a glass transition temperature higher than those of other transparent shape memory polymers is reported.

Development of Thermally-Activated Shape Memory Polymers and Nanocomposites for Biomedical Devices

2017 ◽  
Author(s):  
Jingyu Wang ◽  
Shoieb Chowdhury ◽  
Yingtao Liu ◽  
Bradley Bohnstedt ◽  
Chung-Hao Lee
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Thermal Activation ◽  
Memory Function ◽  
Shape Memory Polymers ◽  
Thermally Activated

Shape memory polymers (SMPs) have been developed as an emerging technology platform for biomedical applications in the past decades. In particular, SMPs are clinically essential for the development of novel medical devices to significantly improve long-term surgical outcomes. In this paper, we synthesized and characterized thermally-activated aliphatic urethane SMPs fabricated with nanocomposites for the design and development of biomedical devices. The thermal activation of shape memory function was investigated by direct thermal activation. Critical polymer properties, such as the glass transition temperature and shape memory function, have been tailored to desired applications, by adjusting the polymer composition. Carbon nanotubes were uniformly dispersed within the polymer during nanocomposite fabrication to significantly enhance the thermal and electrical properties. The synthesized SMPs and nanocomposites were characterized to understand their thermal and mechanical properties using dynamic mechanical analysis (DMA). Scanning electron microscopy was employed to evaluate the dispersion of carbon nanotubes in polymer matrix. The mechanical properties of SMPs and nanocomposites at temperature above their glass transition temperature were evaluated using dog-bone samples in a dual-column mechanical testing system and an environmental chamber. SMPs and nanocomposites will then be fabricated in the form of foam for the development of novel devices applicable to endovascular embolization of cerebral aneurysms.

scholarly journals Transparent, High Glass-Transition Temperature, Shape Memory Hybrid Polyimides Based on Polyhedral Oligomeric Silsesquioxane

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1058 ◽  
Author(s):  
Zhongxu Lan ◽  
Xueli Chen ◽  
Xiao Zhang ◽  
Chongyu Zhu ◽  
Yanlei Yu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Hybrid Films ◽  
Excellent Thermal Stability ◽  
Optically Transparent ◽  
Oligomeric Silsesquioxane

Optically transparent polyimides with excellent thermal stability and shape memory effect have potential applications in optoelectronic devices and aerospace industries. A series of optically transparent shape memory polyimide hybrid films are synthesized from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′-bis-(trifluoromethyl)biphenyl-4,4′-diamine (TFMB) with various polyhedral oligomeric silsesquioxane (POSS) contents and then subjected to thermal imidization. The hybrid films show good optical transparency (>80% at 400 nm and >95% at 500 nm) with cutoff wavelengths ranging from 318 to 336 nm. Following the incorporation of the inorganic POSS structure, the hybrid films exhibit excellent thermal stability with glass transition temperature (Tg) ranging from 351 to 372 °C. The hybrid films possess the highest Tg compared with the previously-reported shape memory polymers. These findings show that POSS is successfully utilized to develop transparent polyimides with excellent thermal stability and shape memory effect.

scholarly journals Electrical Properties of Thiol-ene-based Shape Memory Polymers Intended for Flexible Electronics

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 902 ◽  
Author(s):  
Christopher L. Frewin ◽  
Melanie Ecker ◽  
Alexandra Joshi-Imre ◽  
Jonathan Kamgue ◽  
Jeanneane Waddell ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Electrical Properties ◽  
Shape Memory ◽  
Flexible Electronics ◽  
Shape Memory Polymers ◽  
Curing Process ◽  
Uv Curable ◽  
Processing Technologies

Thiol-ene/acrylate-based shape memory polymers (SMPs) with tunable mechanical and thermomechanical properties are promising substrate materials for flexible electronics applications. These UV-curable polymer compositions can easily be polymerized onto pre-fabricated electronic components and can be molded into desired geometries to provide a shape-changing behavior or a tunable softness. Alternatively, SMPs may be prepared as a flat substrate, and electronic circuitry may be built directly on top by thin film processing technologies. Whichever way the final structure is produced, the operation of electronic circuits will be influenced by the electrical and mechanical properties of the underlying (and sometimes also encapsulating) SMP substrate. Here, we present electronic properties, such as permittivity and resistivity of a typical SMP composition that has a low glass transition temperature (between 40 and 60 °C dependent on the curing process) in different thermomechanical states of polymer. We fabricated parallel plate capacitors from a previously reported SMP composition (fully softening (FS)-SMP) using two different curing processes, and then we determined the electrical properties of relative permittivity and resistivity below and above the glass transition temperature. Our data shows that the curing process influenced the electrical permittivity, but not the electrical resistivity. Corona-Kelvin metrology evaluated the quality of the surface of FS-SMP spun on the wafer. Overall, FS-SMP demonstrates resistivity appropriate for use as an insulating material.

High-temperature carbon plastics based on thermoreactive polyimide binder

2020 ◽  
pp. 89-102
Author(s):  
M. I. Valueva ◽  
I. V. Zelenina ◽  
M. A. Zharinov ◽  
M. A. Khaskov
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Strength Properties ◽  
High Glass Transition Temperature ◽  
Reinforced Plastics ◽  
Carbon Plastics ◽  
Fundamental Possibility ◽  
Fiber Reinforced Plastics

The article presents results of studies of experimental carbon plastics based on thermosetting PMRpolyimide binder. Сarbon fiber reinforced plastics (CFRPs) are made from prepregs prepared by melt and mortar technologies, so the rheological properties of the polyimide binder were investigated. The heat resistance of carbon plastics was researched and its elastic-strength characteristics were determined at temperatures up to 320°С. The fundamental possibility of manufacturing carbon fiber from prepregs based on polyimide binder, obtained both by melt and mortar technologies, is shown. CFRPs made from two types of prepregs have a high glass transition temperature: 364°C (melt) and 367°C (solution), with this temperature remaining at the 97% level after boiling, and also at approximately the same (86–97%) level of conservation of elastic strength properties at temperature 300°С.

Viscoelastic Behavior of Segmented Elastomers

1967 ◽  
Vol 40 (4) ◽  
pp. 1105-1110 ◽  
Author(s):  
Stuart L. Cooper ◽  
Arthur V. Tobolsky
Keyword(s):  
Hydrogen Bonding ◽  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscoelastic Behavior ◽  
Temperature Transition ◽  
Hydrogen Bonding Interactions ◽  
Structural Nature ◽  
Hard Segments

Abstract Viscoelastic behavior of linear segmented elastomers was examined. The unusual properties found in spandex systems are also observable in hydrocarbon block co-polymers, indicating that hydrogen bonding interactions are perhaps not essential. Low temperature properties of segmented systems are governed by the structural nature of the associated flexible segments, which determines the value of the major glass transition temperature (Tg). It appears that an association of the hard segments provides a broad temperature range of enhanced rubbery modulus. This occurs between the major Tg and a secondary high temperature transition.

Experimental Research on Mechanical Behavior of GFRP Bars under High Temperature

2011 ◽  
Vol 71-78 ◽  
pp. 3591-3594 ◽  
Author(s):  
Xiao Lu Wang ◽  
Xiao Xiong Zha
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
High Temperatures ◽  
Glass Fibers ◽  
Ultimate Tensile Stress ◽  
Gfrp Bars ◽  
Tensile Test Result

Experimental results on tensile mechanics properties of GFRP bars at high temperatures are present in this paper. Thirty commercially produced GFRP tensile specimens of 8mm diameter were tested at high temperature ranging from 10°Cup to 500°C. Tensile test result indicates that, the ultimate tensile stress has significant reduction at two temperature zones, one is glass transition temperature of epoxy resin (80-120°C), with strength degradation 22%, the second is the soften temperature of glass fibers(about 400°C), the strength decrease drastically with almost linear rate and remained 33% residual strength at 500°C. The elastic modulus remained unchanged until glass transition temperature of epoxy resin, and the modulus declined linearly with the temperature elevating. Stress-strain relationships of GFRP bars exhibit liner performance even at high temperatures.

scholarly journals Buckling and vibration analysis of shape memory laminated composite beams under axially heterogeneous in-plane loads in the glass transition temperature region

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Nilesh Tiwari ◽  
A. A. Shaikh
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Boundary Conditions ◽  
Shape Memory ◽  
Transition Region ◽  
Shape Memory Polymer ◽  
Shear Deformation Theory ◽  
Effect Of Temperature ◽  
Glass Transition Region

AbstractBuckling and vibration study of the shape memory polymer composites (SMPC) across the glass transition temperature under heterogeneous loading conditions are presented. Finite element analysis based on C° continuity equation through the higher order shear deformation theory (HSDT) is employed considering non linear Von Karman approach to estimate critical buckling and vibration for the temperature span from 273 to 373 K. Extensive numerical investigations are presented to understand the effect of temperature, boundary conditions, aspect ratio, fiber orientations, laminate stacking and modes of phenomenon on the buckling and vibration behavior of SMPC beam along with the validation and convergence study. Effect of thermal conditions, particularly in the glass transition region of the shape memory polymer, is considerable and presents cohesive relation between dynamic modulus properties with magnitude of critical buckling and vibration. Moreover, it has also been inferred that type of axial loading condition along with the corresponding boundary conditions significantly affect the buckling and vibration load across the glass transition region.

scholarly journals Triple-Shape Memory Behavior of Modified Lactide/Glycolide Copolymers

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2984
Author(s):  
Anna Smola-Dmochowska ◽  
Natalia Śmigiel-Gac ◽  
Bożena Kaczmarczyk ◽  
Michał Sobota ◽  
Henryk Janeczek ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Hydroxyl Groups ◽  
Butylene Succinate ◽  
Shape Memory Behavior ◽  
Triple Shape Memory ◽  
High Flexibility ◽  
Bioresorbable Implants

The paper presents the formation and properties of biodegradable thermoplastic blends with triple-shape memory behavior, which were obtained by the blending and extrusion of poly(l-lactide-co-glycolide) and bioresorbable aliphatic oligoesters with side hydroxyl groups: oligo (butylene succinate-co-butylene citrate) and oligo(butylene citrate). Addition of the oligoesters to poly (l-lactide-co-glycolide) reduces the glass transition temperature (Tg) and also increases the flexibility and shape memory behavior of the final blends. Among the tested blends, materials containing less than 20 wt % of oligo (butylene succinate-co-butylene citrate) seem especially promising for biomedical applications as materials for manufacturing bioresorbable implants with high flexibility and relatively good mechanical properties. These blends show compatibility, exhibiting one glass transition temperature and macroscopically uniform physical properties.

Free, partial, and fully constrained recovery analysis of cold-programmed shape memory epoxy/carbon nanotube nanocomposites: Experiments and predictions

2018 ◽  
Vol 29 (10) ◽  
pp. 2164-2176 ◽  
Author(s):  
R Abishera ◽  
R Velmurugan ◽  
KV Nagendra Gopal
Keyword(s):  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Thermally Activated ◽  
Large Structures ◽  
Multi Walled Carbon Nanotube ◽  
Optical Strain Measurement ◽  
Optical Strain

Thermally activated shape memory polymers are typically programmed by initially heating the material above the glass transition temperature ( Tg), deforming to the desired shape, cooling below Tg, and unloading to fix the temporary shape. This process of deforming at high temperatures becomes a time-, labor-, and energy-expensive process while applying to large structures. Alternatively, materials with reversible plasticity shape memory property can be programmed at temperatures well below the glass transition temperature which offers several advantages over conventional programming. Here, the free, partial, and fully constrained recovery analysis of cold-programmed multi-walled carbon nanotube–reinforced epoxy nanocomposites is presented. The free recovery analysis involves heating the temporary shape above Tg without any constraints (zero stress), and for fully constrained recovery analysis, the temporary shape is held constant while heating. The partially constrained recovery behavior is studied by applying a constant stress of 10%, 25%, and 50% of the maximum recovery stress obtained from the completely constrained recovery analysis. The samples are also characterized for their thermal, morphological, and mechanical properties. A non-contact optical strain measurement method is used to measure the strains during cold-programming and shape recovery. The different recovery behaviors are analyzed by using a thermo-viscoelastic–viscoplastic model, and the predictions are compared with the experimental results.

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