Thermo-mechanics of Amorphous Shape-memory Polymers

Nguyen, Thao D.

doi:10.1016/j.piutam.2014.12.017

Cited by 10 publications

(6 citation statements)

References 23 publications

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“…The shape memory effect is not an intrinsic property; it results from the combination of polymer morphology and specific processing. SMPs can be programmed into temporary shapes and return to their original shapes [ 5 ]. The mechanism of the shape memory effect (SME) can be described by two systems within the polymer, these being the net points and switching segments [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Printing Process Parameters on the Shape Transformation Capability of 3D Printed Structures

2021

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The aim of our research was to investigate and optimise the main 3D printing process parameters that directly or indirectly affect the shape transformation capability and to determine the optimal transformation conditions to achieve predicted extent, and accurate and reproducible transformations of 3D printed, shape-changing two-material structures based on PLA and TPU. The shape-changing structures were printed using the FDM technology. The influence of each printing parameter that affects the final printability of shape-changing structures is presented and studied. After optimising the 3D printing process parameters, the extent, accuracy and reproducibility of the shape transformation performance for four-layer structures were analysed. The shape transformation was performed in hot water at different activation temperatures. Through a careful selection of 3D printing process parameters and transformation conditions, the predicted extent, accuracy and good reproducibility of shape transformation for 3D printed structures were achieved. The accurate deposition of filaments in the layers was achieved by adjusting the printing speed, flow rate and cooling conditions of extruded filaments. The shape transformation capability of 3D printed structures with a defined shape and defined active segment dimensions was influenced by the relaxation of compressive and tensile residual stresses in deposited filaments in the printed layers of the active material and different activation temperatures of the transformation.

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Section: Introductionmentioning

confidence: 99%

Effect of Printing Process Parameters on the Shape Transformation Capability of 3D Printed Structures

2021

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“…Lakatos 1 , K. Czifrák 1 whereas the soft segment may overtake the switch function. The reversible switch is linked either with the glass transition (T g ) or with the melting temperature (T m ) depending whether the long-chain soft segments are amorphous or semicrystalline [11]. The SM behavior of segmented PUs was early recognized thereby credit should be given to Tobushi et al [12].…”

Section: Introductionmentioning

confidence: 99%

Segmented linear shape memory polyurethanes with thermoreversible Diels-Alder coupling: Effects of polycaprolactone molecular weight and diisocyanate type

Lakatos¹,

Czifrák²,

Papp³

et al. 2016

Express Polym. Lett.

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Abstract. Segmented linear polyurethanes (PUs) containing Diels-Alder (DA) adduct were synthesized in toluene solution from poly("-caprolactone) (PCL, M n = 10, 25 and 50 kg/mol), diisocyanate (methylene diphenyl diisocyanate (MDI), 2,4-toluene diisocyanate (TDI), 1,6-hexamethylenediisocyanate, (HDI)), furfurylamine (FA) and bismaleimide (BMI). The order of the segments in the PUs was -PCL-MDI-FA-BMI-. The PUs were characterized by size-exclusion chromatography (SEC), different spectroscopic ( 1 H-NMR, attenuated total reflectance Fourier-transform infrared, AT-FTIR), thermal and mechanical analysis (differential scanning calorimetry, DSC, dynamical mechanical analysis, DMA). The DA and retro-DA reactions were identified by 1 H-NMR for both the synthesized PU and the coupling components (i.e. FA and BMI). Tensile mechanical and shape memory (SM) properties of the PUs were also determined. The DA coupling in the PU was improved by heat treatment above the melting temperature (T m ) of PCL. DMA traces showed a plateau-like region above T m of PCL confirming the presence of a physical network the netpoints of which are given by the hard segments including the DA couplers. This feature suggested good SM behavior that was confirmed both qualitatively and quantitatively.

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“…Upon reheating the tube to higher than T g , the deformed shape spontaneously restores to its permanent shape due to the favorable tendency for an increase in entropy. [68][69][70][71] Based on the excellent SME of the tube, the shape of the tube can be adjusted as desired, and the direction of the tube's asymmetric gradient can be reversibly changed.…”

Section: Mechanism Of In Situ Controlled Self-transportmentioning

confidence: 99%

Magnetic Responsive On‐Site Switching of the Directional Droplet Self‐Transport in Shape Memory Slippery Tube

Wang

Jin

et al. 2023

Adv Funct Materials

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The phenomenon of controlled droplet transport has promising application prospects in various fields. Active droplet transport mode is controllable through continuous external stimuli. By contrast, self‐transport is a more environmentally friendly and energy‐efficient passive transport mode but lacks controllability. In this study, controlled self‐transport is achieved by constructing a shape memory polymer (SMP) tube with a lubricated magnetic‐responsive gel inner surface. The asymmetrical shape of the tube, combined with the lubricated inner surface, enables directional self‐transport of droplets without external stimuli. Furthermore, the resistance on the inner gel surface can be altered by regulating the magnetic field to achieve effective active control during the self‐transport process. Thus, smart in situ control of droplet transport can be achieved by integrating the macroscale shape variation of the tube with the dynamic control of the inner surface microstructure. Owing to the fast magnetic responsivity and in situ controllability of the self‐transport process, the SMP lubricated tube demonstrates the ability to transport a variety of liquids and can be designed as a micro‐reactor for step‐by‐step droplet detection. The findings of this study may provide guidance for the development of intelligent interface materials and microfluidic devices.

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Thermo-mechanics of Amorphous Shape-memory Polymers

Cited by 10 publications

References 23 publications

Effect of Printing Process Parameters on the Shape Transformation Capability of 3D Printed Structures

Effect of Printing Process Parameters on the Shape Transformation Capability of 3D Printed Structures

Segmented linear shape memory polyurethanes with thermoreversible Diels-Alder coupling: Effects of polycaprolactone molecular weight and diisocyanate type

Magnetic Responsive On‐Site Switching of the Directional Droplet Self‐Transport in Shape Memory Slippery Tube

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