Self-healing thermoplastic polyurethane (TPU)/polycaprolactone (PCL) /multi-wall carbon nanotubes (MWCNTs) blend as shape-memory composites

In this study, a series of heat-induced shape memory composites was prepared by the hot-melt extrusion and three-dimensional (3D) printing of thermoplastic polyurethane (TPU) using wood flour (WF) with different contents of EPDM-g-MAH. The mechanical properties, microtopography, thermal property analysis, and heat-induced shape memory properties of the composites were examined. The results showed that, when the EPDM-g-MAH content was 4%, the tensile elongation and tensile strength of the composites reached the maximum value. The scanning electron microscopy and dynamic mechanical analysis results revealed a good interface bonding between TPU and WF when the EPDM-g-MAH content was 4%. The thermogravimetric analysis indicated that the thermal stability of TPU/WF composites was enhanced by the addition of 4% EPDM-g-MAH. Heat-induced shape memory test results showed that the shape memory performance of composites with 4% EPDM-g-MAH was better than that of unmodified-composites. The composites’ shape recovery performance at a temperature of 60 °C was higher than that of the composites at ambient temperature. It was also found that, when the filling angle of the specimen was 45°, the recovery angle of the composites was larger.

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Polyurethane-Carbon Nanotubes Composite Dual Band Antenna for Wearable Applications

Polymers ◽

10.3390/polym12112759 ◽

2020 ◽

Vol 12 (11) ◽

pp. 2759

Author(s):

Robert Olejník ◽

Stanislav Goňa ◽

Petr Slobodian ◽

Jiří Matyáš ◽

Robert Moučka ◽

...

Keyword(s):

Carbon Nanotubes ◽

Thermoplastic Polyurethane ◽

Conductive Filler ◽

Dip Coating ◽

Dual Band ◽

Wearable Electronics ◽

Frequency Bands ◽

Multi Wall Carbon Nanotubes ◽

Dual Band Antenna ◽

Base Composite

The design of a unipole and a dual band F-shaped antenna was conducted to find the best parameters of prepared antenna. Antenna radiator part is fully made of polymer and nonmetal base composite. Thermoplastic polyurethane (PU) was chosen as a matrix and multi-wall carbon nanotubes (MWCNT) as an electrical conductive filler, which creates conductive network. The use of the composite for the antenna has the advantage in simple preparation through dip coating technique. Minor disadvantage is the usage of solvent for composite preparation. Composite structure was used for radiator part of antenna. The antenna operates in 2.45 and 5.18 GHz frequency bands. DC conductivity of our PU/MWCNT composite is about 160 S/m. With this material, a unipole and a dual band F antenna were realized on 2 mm thick polypropylene substrate. Both antenna designs were also simulated using finite integration technique in the frequency domain (FI-FD). Measurements and full wave simulations of S11 of the antenna showed good agreement between measurements and simulations. Except for S11, the gain and radiation pattern of the antennas were measured and simulated. Maximum gain of the designed unipole antenna is around −10.0 and −5.5 dBi for 2.45 and 5.18 GHz frequency bands, respectively. The manufactured antennas are intended for application in wearable electronics, which can be used to monitor various activities such as walking, sleeping, heart rate or food consumption.

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Development of aeronautical epoxy nanocomposites having an integrated selfhealing ability

MATEC Web of Conferences ◽

10.1051/matecconf/201823300021 ◽

2018 ◽

Vol 233 ◽

pp. 00021 ◽

Cited By ~ 1

Author(s):

Liberata Guadagno ◽

Luigi Vertuccio ◽

Carlo Naddeo ◽

Elisa Calabrese ◽

Giuseppina Barra ◽

...

Keyword(s):

Carbon Nanotubes ◽

Barbituric Acid ◽

Mechanical Analysis ◽

Self Healing ◽

Multi Wall Carbon Nanotubes ◽

Healing Efficiency ◽

Donor And Acceptor ◽

Rubber Toughened ◽

Hydrogen Bondings ◽

Functionalized Mwcnts

Functionalized multi-wall carbon nanotubes (MWCNTs) have been embedded in a rubber-toughened epoxy formulation in order to explore the possibility to impart an auto-repair function to the epoxy matrix. The nanofiller has been covalently functionalized with hydrogen bonding moieties able to act as donor and acceptor of hydrogen bondings. Healing efficiencies have been evaluated for nano charged epoxy formulations at a loading of 0.5% wt/wt of functionalized MWCNTs bearing barbituric acid and thymine-based ligands. For both the performed functionalizations, a self-healing efficiency higher than 50% has been found. Dynamic Mechanical Analysis (DMA) highlights that the inclusion of nanofiller increases the storage moduli. Furthermore, DMA analysis evidences the presence of a phase characterized by a greater mobility of the epoxy chains, which promotes the activation of self-healing mechanisms.

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

Polymers ◽

10.3390/polym11101586 ◽

2019 ◽

Vol 11 (10) ◽

pp. 1586 ◽

Cited By ~ 10

Author(s):

Wu ◽

Gu ◽

Hou ◽

Li ◽

Ke ◽

...

Keyword(s):

Carbon Nanotubes ◽

Shape Memory ◽

Shape Recovery ◽

Thermoplastic Polyurethane ◽

Cellulose Nanofibers ◽

Hybrid Nanocomposites ◽

Large Strains ◽

Strain Sensing ◽

Shape Memory Effects ◽

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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