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.

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.

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.

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.

scholarly journals Modelling the Mechanical and Strain Recovery Behaviour of Partially Crystalline PLA

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1342 ◽  
Author(s):  
John Sweeney ◽  
Paul Spencer ◽  
Karthik Nair ◽  
Phil Coates
Keyword(s):  
Finite Element ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Stress Relaxation ◽  
Shape Memory ◽  
Yield Stress ◽  
Amorphous Phase ◽  
Strain Recovery ◽  
Stress Strain

This is a study of the modelling and prediction of strain recovery in a polylactide. Strain recovery near the glass transition temperature is the underlying mechanism for the shape memory in an amorphous polymer. The investigation is aimed at modelling such shape memory behaviour. A PLA-based copolymer is subjected to stress–strain, stress relaxation and strain recovery experiments at large strain at 60 °C just below its glass transition temperature. The material is 13% crystalline. Using published data on the mechanical properties of the crystals, finite element modelling was used to determine the effect of the crystal phase on the overall mechanical behaviour of the material, which was found to be significant. The finite element models were also used to relate the stress–strain results to the yield stress of the amorphous phase. This yield stress was found to possess strain rate dependence consistent with an Eyring process. Stress relaxation experiments were also interpreted in terms of the Eyring process, and a two-process Eyring-based model was defined that was capable of modelling strain recovery behaviour. This was essentially a model of the amorphous phase. It was shown to be capable of useful predictions of strain recovery.

Flexural Testing of Shape Memory Polymers for Morphing Aircraft Applications

2007 ◽  
Author(s):  
Korey Gross ◽  
Lisa Weiland
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Shape Memory ◽  
Shape Memory Polymers ◽  
Morphing Aircraft ◽  
Flexural Testing ◽  
Soft State ◽  
Out Of Plane ◽  
Hard State ◽  
Significant Attention

Shape memory polymers (SMPs) have garnered significant attention in recent years for their potential to return to a “memorized” state when warmed above their glass transition temperature Tg. However, they also have potential in morphing aircraft applications because of their significant modulus change above and below Tg. Much less energy is required to deform this material when in its soft state, but when the material returns to the hard state, it is able to support significant loads. In the proposed effort, SMP is experimentally considered as a candidate material for morphing aircraft applications where the material’s ability to support out of plane loads above and below the Tg is of primary importance. The SMP of study in the work is Veriflex®.

Synthesis of Novel Hyperbranched Polyurethane Acrylate Based on Pentaerythritol

2015 ◽  
Vol 731 ◽  
pp. 515-519
Author(s):  
Yu Xiu Wang ◽  
Guang Xue Chen
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Single Step ◽  
Urethane Acrylate ◽  
Uv Curable ◽  
Hyperbranched Polyesters ◽  
Three Generations ◽  
Two Stages ◽  
High Degree

To study the structure and properties of hyperbranched polyesters as well as the modified ones. Three generations of hyperbranched polyesters named HBPE-1, HBPE-2 and HBPE-3 were synthesized by the reactions from pentaerythritol and 2,2-dihydroxy-methyl-propionic acid by single-step polycondensation. They were characterized by 1H NMR, 13C NMR and the results indicated they possessed a high degree of branching. Then homemade urethane acrylate prepolymer reacted with three generations of hydroxyl-terminated hyperbranched polyesters introducing C=C contents, the product was characterized by FT-IR, DSC, TGA techniques. The results of TGA showed well thermal stability of all the products. TGA curves of the modified HBPES showed two stages, 280-350°C means pyrolysis of main chain ester section and 400-450°C means pyrolysis of urethane acrylate section. The results of DSC indicated that glass transition temperature increased with the number of the hyperbranched polyester units’ increment. What’s more, glass transition temperature of HBPE-3 was 48.13°C. HPUA-3 was semi-crystalline material, its glass transition temperature was-12.59°C, cold crystallization temperature Tc 110.92°C, melting temperature Tm 134.74°C. Since the introduction of a large number of unsaturated units to the end, the resin can be introduced into the UV-curable systems for paints, inks, adhesives and some other fields.

Electrical Properties of Polymer Composites

2005 ◽  
Vol 482 ◽  
pp. 391-394
Author(s):  
T. Podgrabinski ◽  
Petr Slepička ◽  
V. Rybka ◽  
Václav Švorčík
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Electrical Properties ◽  
Hysteresis Loops ◽  
Temperature Hysteresis ◽  
Electrical Field ◽  
Measured Polarization ◽  
Pmma Solution

Permittivity of about 1 µm thin films prepared from polymethylmetactrylate (PMMA) solution doped with 20 % of diphenyl sulfoxide was studied. Permittivity of the films was measured as a function of the temperature. The measurement of the dependence of polarization on electrical field was performed using a standard Sawyer-Tower circuit. The presence of the dopant increases the composite permittivity namely above the PMMA glass transition temperature. Hysteresis loops observed on the measured polarization vs. electrical field dependence indicate easier and more pronounced polarizability of the composite comparing to pristine PMMA.

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