Hybrid Nanocomposites of Cellulose/Carbon-Nanotubes/Polyurethane with Rapidly Water Sensitive Shape Memory Effect and Strain Sensing Performance

In this work, a fast water-responsive shape memory hybrid polymer based on thermoplastic polyurethane (TPU) was prepared by crosslinking with hydroxyethyl cotton cellulose nanofibers (CNF-C) and multi-walled carbon nanotubes (CNTs). The effect of CNTs content on the electrical conductivity of TPU/CNF-C/CNTs nanocomposite was investigated for the feasibility of being a strain sensor. In order to know its durability, the mechanical and water-responsive shape memory effects were studied comprehensively. The results indicated good mechanical properties and sensing performance for the TPU matrix fully crosslinked with CNF-C and CNTs. The water-induced shape fixity ratio (Rf) and shape recovery ratio (Rr) were 49.65% and 76.64%, respectively, indicating that the deformed composite was able to recover its original shape under a stimulus. The TPU/CNF-C/CNTs samples under their fixed and recovered shapes were tested to investigate their sensing properties, such as periodicity, frequency, and repeatability of the sensor spline under different loadings. Results indicated that the hybrid composite can sense large strains accurately for more than 103 times and water-induced shape recovery can to some extent maintain the sensing accuracy after material fatigue. With such good properties, we envisage that this kind of composite may play a significant role in developing new generations of water-responsive sensors or actuators.

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A Thermally-Electrically Double-Responsive Polycaprolactone - Thermoplastic polyurethane / Multi-walled Carbon Nanotubes Fiber Assisted with Highly Effective Shape Memory and Strain Sensing Performance

Chemical Engineering Journal ◽

10.1016/j.cej.2021.131648 ◽

2021 ◽

pp. 131648

Author(s):

Meijie Qu ◽

Hai Wang ◽

Qiushan Chen ◽

Lu Wu ◽

Ping Tang ◽

...

Keyword(s):

Carbon Nanotubes ◽

Shape Memory ◽

Thermoplastic Polyurethane ◽

Strain Sensing ◽

Highly Effective ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes ◽

Sensing Performance

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Characterization of Creeping and Shape Memory Effect in Laser Sintered Thermoplastic Polyurethane

Journal of Computing and Information Science in Engineering ◽

10.1115/1.4034032 ◽

2016 ◽

Vol 16 (4) ◽

Cited By ~ 19

Author(s):

Shangqin Yuan ◽

Jiaming Bai ◽

Chee Kai Chua ◽

Kun Zhou ◽

Jun Wei

Keyword(s):

Shape Memory ◽

Shape Recovery ◽

Thermoplastic Polyurethane ◽

Selective Laser Sintering ◽

Thermal Transitions ◽

Temperature Dependent ◽

Shape Memory Effects ◽

Viscoelastic Behaviors ◽

High Flexibility

Thermoplastic polyurethane (TPU) powders were successfully processed in a selective laser sintering (SLS) system. The laser-sintered polyurethane products with viscoelastic behaviors exhibit high flexibility and elongation at break at room temperature. Moreover, the creeping and the thermoresponsive shape-memory effects (SME) were also characterized. The influences of the time-temperature relevant parameters on the shape-fixity and shape-recovery ratios were investigated quantitatively. The creeping and SME were time–temperature dependent phenomena, and the shape recovery mechanism is associated to the microsegments thermal transitions within the polymer matrix.

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Shape-Memory-Recovery Characteristics of Microcellular Foamed Thermoplastic Polyurethane

Polymers ◽

10.3390/polym12020351 ◽

2020 ◽

Vol 12 (2) ◽

pp. 351

Author(s):

Chang-Seok Yun ◽

Joo Seong Sohn ◽

Sung Woon Cha

Keyword(s):

Shape Memory ◽

Cell Density ◽

Shape Recovery ◽

Structural Changes ◽

Thermoplastic Polyurethane ◽

Testing Machine ◽

Base Material ◽

Memory Mechanism ◽

Foaming Process ◽

Dog Bone

We investigated the shape-recovery characteristics of thermoplastic polyurethane (TPU) with a microcellular foaming process (MCP). Additionally, we investigated the correlation between changes in the microstructure and the shape-recovery characteristics of the polymers. TPU was selected as the base material, and the shape-recovery characteristics were confirmed using a universal testing machine, by manufacturing dog-bone-type injection-molded specimens. TPUs are reticular polymers with both soft and hard segments. In this study, we investigated the shape-memory mechanism of foamed polymers by maximizing the shape-memory properties of these polymers through a physical foaming process. Toward this end, TPU specimens were prepared by varying the gas pressure, foaming temperature, and type of foaming gas in the batch MCP. The effects of internal structural changes were investigated. These experimental variables affected the microstructure and shape-recovery characteristics of the foamed polymer. The generated cell density changed, which affected the shape-recovery characteristics. In general, a higher cell density corresponded to a higher shape-recovery ratio.

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Shape memory effects of EVM-GMA/PVC blends

Journal of Elastomers & Plastics ◽

10.1177/0095244320953589 ◽

2020 ◽

pp. 009524432095358

Author(s):

Yanlu Chen ◽

Zhengwei Lin ◽

Haotian Zhao ◽

Xingxing Ji ◽

Xinyan Shi

Keyword(s):

Shape Memory ◽

Glycidyl Methacrylate ◽

Shape Recovery ◽

Physical And Mechanical Properties ◽

Ethylene Vinyl Acetate ◽

Recovery Efficiency ◽

Restoring Force ◽

Shape Memory Properties ◽

Shape Memory Effects ◽

Two Phases

In this paper, polyvinyl chloride (PVC) masterbatch, prepared using ethylene-vinyl acetate-glycidyl methacrylate terpolymer (EVM-GMA) as a polymer plasticizer replacing traditional harmful ester, was blended with EVM-GMA in melt and then cured by peroxide in a compression mold to prepare EVM-GMA/PVC blends. The results showed that with the increase of PVC, physical and mechanical properties have improved significantly. Two phases in blends formed a “sea-island” structure and the interface was blurred. Blends riched in EVM-GMA all had excellent dual shape memory properties. After removing applied force, there was only a slight recovery of the instantaneous elastic deformation and blends still retained the original temporary shape (the shape fixation was more than 99%). The shape recovery efficiency of specimen (EVM-GMA/PVC = 90/10) was the highest, which evidenced that entropy elastic effect of molecular chains and elastic restoring force provided by crosslinked structure achieved a balance at this point.

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