Characterizing and Modeling the Free Recovery and Constrained Recovery Behavior of a Polyurethane Shape Memory Polymer

2010 ◽  
Author(s):  
Brent L. Volk ◽  
Dimitris C. Lagoudas ◽  
Duncan J. Maitland
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Tensile Tests ◽  
Stress Recovery ◽  
Shear Moduli ◽  
Recovery Experiment

In this work, tensile tests are performed on a polyurethane shape memory polymer for both free recovery (extension recovery at zero load) and constrained recovery (stress recovery at constant extension) conditions. The experimental characterization is conducted on an electromechanical screw driven test frame, and a laser extensometer is used in conjunction with the electromechanical frame to provide a non-contact technique for measuring the deformation of the material. The specimens are deformed, above the glass transition temperature, to 10% extension. The SMP is then cooled, at a constant value of extension, to below the glass transition temperature to ‘lock’ the temporary shape. The extension recovery at zero load as well as the stress recovery at a constant value of extension is measured during the first shape memory cycle as the SMP is heated to above its glass transition temperature. The material is observed to recover 93% of the applied deformation when heated at zero load. In addition, a stress recovery of 1.5 MPa is observed when heated while holding a constant value of deformation (10% extension). After performing the experiments, the Chen and Lagoudas model, implemented in 1-D by Volk, et al., is used to simulate and predict the experimental results. The material properties used in the model — namely the coefficients of thermal expansion, shear moduli, and frozen volume fraction — are calibrated from a single free recovery experiment. The calibrated model is then used to simulate the material response for the free recovery tests as well as predict the response for the constrained recovery condition. The model simulations agree well with the free recovery experimental data but predict a larger compressive stress than what is observed during the constrained recovery experiment.

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 Advanced Infill Designs for 3D Printed Shape-Memory Components

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1225
Author(s):  
Daniel Koske ◽  
Andrea Ehrmann
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
Fused Deposition Modeling ◽  
Shape Memory Polymer ◽  
The Other ◽  
Poly Lactic Acid ◽  
Fused Deposition ◽  
Other Hand

Poly(lactic acid) (PLA) is one of the most often used polymers in 3D printing based on the fused deposition modeling (FDM) method. On the other hand, PLA is also a shape memory polymer (SMP) with a relatively low glass transition temperature of ~60 °C, depending on the exact material composition. This enables, on the one hand, so-called 4D printing, i.e., printing flat objects which are deformed afterwards by heating them above the glass transition temperature, shaping them and cooling them down in the desired shape. On the other hand, objects from PLA which have been erroneously deformed, e.g., bumpers during an accident, can recover their original shape to a certain amount, depending on the applied temperature, the number of deformation cycles, and especially on the number of broken connections inside the object. Here, we report on an extension of a previous study, investigating optimized infill designs which avoid breaking in 3-point bending tests and thus allow for multiple repeated destruction and recovery cycles with only a small loss in maximum force at a certain deflection.

Curved Type Pneumatic Artificial Rubber Muscle Using Shape-Memory Polymer

2012 ◽  
Vol 24 (3) ◽  
pp. 472-479 ◽  
Author(s):  
Kazuto Takashima ◽  
◽  
Toshiro Noritsugu ◽  
Jonathan Rossiter ◽  
Shijie Guo ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Memory ◽  
External Force ◽  
Shape Memory Polymer ◽  
Fiber Reinforcement ◽  
Artificial Muscle ◽  
Pneumatic Artificial Muscle ◽  
Initial Shape

A novel pneumatic artificial muscle actuator is presented which is based on the design of a conventional curved type pneumatic bellows actuator. By inhibiting the extension of one side with fiber reinforcement, bending motion can be induced when air is supplied to the internal bladder. In this study, we developed a new actuator by replacing the fiber reinforcement with a Shape-Memory Polymer (SMP). The SMP can be deformed above its glass transition temperature (Tg) and maintains a rigid shape after it is cooled below Tg. When next heated above Tg, it returns to its initial shape. When only part of our actuator is warmed above Tg, only that portion of the SMP is soft and can actuate. Therefore, the direction of the motion can be controlled by heating. Moreover, our actuator can be deformed by an external force above Tg and fixed by cooling it below Tg.

scholarly journals Synthesis, Properties, and Biodegradability of Thermoplastic Elastomers Made from 2-Methyl-1,3-propanediol, Glutaric Acid and Lactide

Life ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 43
Author(s):  
Lamya Zahir ◽  
Takumitsu Kida ◽  
Ryo Tanaka ◽  
Yuushou Nakayama ◽  
Takeshi Shiono ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glutaric Acid ◽  
Triblock Copolymers ◽  
Tensile Tests ◽  
Thermoplastic Elastomers ◽  
Proteinase K ◽  
Synthesis Properties

An innovative type of biodegradable thermoplastic elastomers with improved mechanical properties from very common and potentially renewable sources, poly(L-lactide)-b-poly(2-methyl-1,3-propylene glutarate)-b-poly(L-lactide) (PLA-b-PMPG-b-PLA)s, has been developed for the first time. PLA-b-PMPG-b-PLAs were synthesized by polycondensation of 2-methyl-1,3-propanediol and glutaric acid and successive ring-opening polymerization of L-lactide, where PMPG is an amorphous central block with low glass transition temperature and PLA is hard semicrystalline terminal blocks. The copolymers showed glass transition temperature at lower than −40 °C and melting temperature at 130–152 °C. The tensile tests of these copolymers were also performed to evaluate their mechanical properties. The degradation of the copolymers and PMPG by enzymes proteinase K and lipase PS were investigated. Microbial biodegradation in seawater was also performed at 27 °C. The triblock copolymers and PMPG homopolymer were found to show 9–15% biodegradation within 28 days, representing their relatively high biodegradability in seawater. The macromolecular structure of the triblock copolymers of PLA and PMPG can be controlled to tune their mechanical and biodegradation properties, demonstrating their potential use in various applications.

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