scholarly journals Electrically Self-Healing Thermoset MWCNTs Composites Based on Diels-Alder and Hydrogen Bonds

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1885 ◽  
Author(s):  
Macedo Lima ◽  
Orozco ◽  
Picchioni ◽  
Moreno-Villoslada ◽  
Pucci ◽  
...  
Keyword(s):  
Polymer Nanocomposites ◽  
Thermomechanical Properties ◽  
Diels Alder ◽  
Product Performance ◽  
Hydroxyl Groups ◽  
Self Healing ◽  
Electrically Conductive ◽  
Hydrogen Bonding Interactions ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this work, we prepared electrically conductive self-healing nanocomposites. The material consists of multi-walled carbon nanotubes (MWCNT) that are dispersed into thermally reversible crosslinked polyketones. The reversible nature is based on both covalent (Diels-Alder) and non-covalent (hydrogen bonding) interactions. The design allowed for us to tune the thermomechanical properties of the system by changing the fractions of filler, and diene-dienophile and hydroxyl groups. The nanocomposites show up to 1 × 104 S/m electrical conductivity, reaching temperatures between 120 and 150 °C under 20–50 V. The self-healing effect, induced by electricity was qualitatively demonstrated as microcracks were repaired. As pointed out by electron microscopy, samples that were already healed by electricity showed a better dispersion of MWCNT within the polymer. These features point toward prolonging the service life of polymer nanocomposites, improving the product performance, making it effectively stronger and more reliable.

scholarly journals Temperature-Dependent Synergistic Effect of Multi-Walled Carbon Nanotubes and Graphene Nanoplatelets on the Tensile Quasi-Static and Fatigue Properties of Epoxy Nanocomposites

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 84
Author(s):  
Yi-Ming Jen ◽  
Hao-Huai Chang ◽  
Chien-Min Lu ◽  
Shin-Yu Liang
Keyword(s):  
Carbon Nanotubes ◽  
Fatigue Strength ◽  
Synergistic Effect ◽  
Polymer Nanocomposites ◽  
Graphene Nanoplatelets ◽  
Temperature Dependent ◽  
Epoxy Nanocomposites ◽  
Hybrid Fillers ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Even though the characteristics of polymer materials are sensitive to temperature, the mechanical properties of polymer nanocomposites have rarely been studied before, especially for the fatigue behavior of hybrid polymer nanocomposites. Hence, the tensile quasi-static and fatigue tests for the epoxy nanocomposites reinforced with multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were performed at different temperatures in the study to investigate the temperature-dependent synergistic effect of hybrid nano-fillers on the studied properties. The temperature and the filler ratio were the main variables considered in the experimental program. A synergistic index was employed to quantify and evaluate the synergistic effect of hybrid fillers on the studied properties. Experimental results show that both the monotonic and fatigue strength decrease with increasing temperature significantly. The nanocomposites with a MWCNT (multi-walled CNT): GNP ratio of 9:1 display higher monotonic modulus/strength and fatigue strength than those with other filler ratios. The tensile strengths of the nanocomposite specimens with a MWCNT:GNP ratio of 9:1 are 10.0, 5.5, 12.9, 23.4, and 58.9% higher than those of neat epoxy at −28, 2, 22, 52, and 82 °C, respectively. The endurance limits of the nanocomposites with this specific filler ratio are increased by 7.7, 26.7, 5.6, 30.6, and 42.4% from those of pristine epoxy under the identical temperature conditions, respectively. Furthermore, the synergistic effect for this optimal nanocomposite increases with temperature. The CNTs bridge the adjacent GNPs to constitute the 3-D network of nano-filler and prevent the agglomeration of GNPs, further improve the studied strength. Observing the fracture surfaces reveals that crack deflect effect and the bridging effect of nano-fillers are the main reinforcement mechanisms to improve the studied properties. The pullout of nano-fillers from polymer matrix at high temperatures reduces the monotonic and fatigue strengths. However, high temperature is beneficial to the synergistic effect of hybrid fillers because the nano-fillers dispersed in the softened matrix are easy to align toward the directions favorable to load transfer.

Modification of Multi-Walled Carbon Nanotubes by Diels-Alder and Sandmeyer Reactions

2007 ◽  
Vol 7 (8) ◽  
pp. 2795-2807 ◽  
Author(s):  
A. Gergely ◽  
J. Telegdi ◽  
E. Mészáros ◽  
Z. Pászti ◽  
G. Tárkányi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Diels Alder ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

New Chain Extenders for Self-Healing Polymers

2021 ◽  
Vol 899 ◽  
pp. 628-637
Author(s):  
Daria V. Zakharova ◽  
Zalina A. Lok’yaeva ◽  
Alexander A. Pavlov ◽  
Alexander V. Polezhaev
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Hydroxyl Groups ◽  
Structural Fragment ◽  
Self Healing ◽  
Diels Alder Reaction ◽  
Small Series ◽  
Chain Extenders ◽  
Reversible Covalent ◽  
Thermochemical Parameters

We present here a small series of compounds designed to modify the polymer chain of various polyurethanes in order to introduce a structural fragment with the ability of thermally-triggered reversible covalent interactions. Bismaleimides (2a-2e) were synthesized from commercially available aromatic and aliphatic symmetric diamines (1a-1e) and were further introduced into the Diels-Alder reaction with furfuryl alcohol as dienophiles. The Diels-Alder adducts (3a-3e) were obtained as a mixture of endo- and exo-isomer. The presence of symmetrical hydroxyl groups in the structure of the obtained compounds makes them suitable as chain extenders of low molecular weight diisocyanate prepolymers. The presence of a thermally reversible Diels-Alder reaction adduct in the structure of potential chain-extenders opens a possibility to create unique materials with self-healing properties. All compounds obtained were characterized by 1H, 13C NMR, ESI-HRMS, and IR spectroscopy. The thermochemical parameters of the reverse Diels-Alder reaction were established using DSC analysis.

Dielectric and Thermomechanical Properties of Polypropylene/Multi-Walled Carbon Nanotubes Nanocomposites

2007 ◽  
Vol 1056 ◽  
Author(s):  
A. Kanapitsas ◽  
E. Logakis ◽  
C. Pandis ◽  
I. Zuburtikudis ◽  
P. Pissis ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Percolation Threshold ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Dielectric Relaxation Spectroscopy ◽  
Melt Mixing ◽  
Polypropylene Nanocomposites ◽  
Multi Walled Carbon Nanotubes ◽  
Permittivity Measurements ◽  
Walled Carbon Nanotubes

ABSTRACTThe purpose of this work is to examine the dielectric, electrical and thermo-mechanical properties of multi-walled carbon nanotubes (MWCNT) filled polypropylene nanocomposites formed by melt-mixing. To that aim dielectric relaxation spectroscopy (DRS) and dymamic mechanical analysis (DTMA) were employed. The results are discussed in terms of nucleating action of MWCNT and interfacial polymer-filler interactions. Special attention is paid to percolation aspects by both ac conductivity measurements for the samples which are above the percolation threshold and permittivity measurements for the samples which are below percolation threshold.

Electrochemical Impedance Studies on Single and Multi-Walled Carbon Nanotubes—Polymer Nanocomposites for Biosensors Development

2015 ◽  
Vol 15 (5) ◽  
pp. 3385-3393 ◽  
Author(s):  
Mihaela Tertiş ◽  
Anca Florea ◽  
Bogdan Feier ◽  
Iuliu Ovidiu Marian ◽  
Luminţa Silaghi-Dumitrescu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Polymer Nanocomposites ◽  
Electrochemical Impedance ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes
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