scholarly journals Toughening and Healing of CFRPs by Electrospun Diels–Alder Based Polymers Modified with Carbon Nano-Fillers

2021 ◽  
Vol 5 (9) ◽  
pp. 242
Author(s):  
Athanasios Kotrotsos ◽  
Constantinos Rouvalis ◽  
Anna Geitona ◽  
Vassilis Kostopoulos
Keyword(s):  
High Performance ◽  
Healing Process ◽  
Electrospinning Process ◽  
Diels Alder ◽  
Self Healing ◽  
Reinforced Plastics ◽  
Fiber Bridging ◽  
Carbon Nano Tubes ◽  
Solution Electrospinning ◽  
Areas Of Interest

In the present investigation, thermo-reversible bonds formed between maleimide and furan groups (Diels–Alder (DA)-based bis-maleimides (BMI)) have been generated to enable high-performance unidirectional (UD) carbon fiber-reinforced plastics (CFRPs) with self-healing (SH) functionality. The incorporation of the SH agent (SHA) was performed locally, only in areas of interest, with the solution electrospinning process (SEP) technique. More precisely, reference and modified CFRPs with (a) pure SHA, (b) SHA modified with multi-walled carbon nano-tubes (MWCNTs) and (c) SHA modified with graphene nano-platelets (GNPs) were fabricated and further tested under Mode I loading conditions. According to experimental results, it was shown that the interlaminar fracture toughness properties of modified CFRPs were considerably enhanced, with GNP-modified ones to exhibit the best toughening performance. After the first fracture and the activation of the healing process, C-scan inspections revealed, macroscopically, a healing efficiency (H.E.) of 100%; however, after repeating the tests, a low recovery of mechanical properties was achieved. Finally, optical microscopy (OM) examinations not only showed that the epoxy matrix at the interface was partly infiltrated by the DA resin, but it also revealed the presence of pulled-out fibers at the fractured surfaces, indicating extended fiber bridging between crack flanks due to the presence of the SHA.

scholarly journals Rapid self-healing and recycling of multiple-responsive mechanically enhanced epoxy resin/graphene nanocomposites

RSC Advances ◽  
2017 ◽  
Vol 7 (73) ◽  
pp. 46336-46343 ◽  
Author(s):  
Chenting Cai ◽  
Yue Zhang ◽  
Xueting Zou ◽  
Rongchun Zhang ◽  
Xiaoliang Wang ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
High Performance ◽  
Diels Alder ◽  
Self Healing ◽  
Covalent Bonds ◽  
Graphene Nanocomposites ◽  
Graphene Nanocomposite

A rapid self-healing and recyclable high-performance crosslinked epoxy resin (ER)/graphene nanocomposite is reported by simultaneously incorporating thermally reversible Diels–Alder (DA) covalent bonds and multiple-responsive graphene into the ER matrix.

scholarly journals Microencapsulated healing agents for an elevated-temperature cured epoxy: Influence of viscosity on healing efficiency

2021 ◽  
pp. 096739112110453
Author(s):  
Habibah Ghazali ◽  
Lin Ye ◽  
Amie N Amir
Keyword(s):  
Fracture Toughness ◽  
Elevated Temperature ◽  
High Performance ◽  
Healing Process ◽  
Polymer Network ◽  
Diglycidyl Ether ◽  
The Self ◽  
Effect Of Temperature ◽  
Mode I ◽  
Self Healing

Among many applications, elevated-temperature cured epoxy resins are widely used for high-performance applications especially for structural adhesive and as a matrix for structural composites. This is due to their superior chemical and mechanical properties. The thermosetting nature of epoxy produces a highly cross-linked polymer network during the curing process where the resulting material exhibited excellent properties. However, due to this cross-linked molecular structure, epoxies are also known to be brittle, and once a crack initiated in the material, it is difficult to arrest the crack propagation. Earlier research found that the inclusion of encapsulated healing agents is able to introduce self-healing ability to the room-temperature cured epoxies. The current study investigated the self-healing behaviour of an elevated-temperature cured epoxy, which incorporated the dual-capsule system loaded with diglycidyl-ether of bisphenol-A (DGEBA) resin and mercaptan. The microcapsules were prepared by the in-situ polymerisation method while the fracture toughness and the self-healing capability of the tapered-double-cantilever-beam (TDCB) epoxy specimens were measured under Mode-I fracture toughness testing. We investigated the effect of temperature on viscosity of the healing agents and how these values influence the formation of uniform healing on the fracture surfaces. It was found that incorporation of the dual-capsule self-healing system onto an elevated-temperature cured epoxy slightly changed the fracture toughness of the epoxy as indicated by the Mode-I testing. In the case of thermal healing at 70°C, the self-healing epoxy exhibited a recovery of up to 111% of its original fracture toughness, where a uniform spreading of the healant was observed. The excellent healing behaviour is attributed to the lower viscosity of the healant at higher temperature and the higher glass transition temperature ( Tg) of the produced healant film. The DSC analysis confirmed that the healing process was not contributed by the post-curing of the host epoxy.

scholarly journals Polymer nanocomposite-enabled high-performance triboelectric nanogenerator with self-healing capability

RSC Advances ◽  
2018 ◽  
Vol 8 (54) ◽  
pp. 30661-30668 ◽  
Author(s):  
Huidan Niu ◽  
Xinyu Du ◽  
Shuyu Zhao ◽  
Zuqing Yuan ◽  
Xiuling Zhang ◽  
...  
Keyword(s):  
High Performance ◽  
Healing Process ◽  
Polymer Nanocomposite ◽  
The Self ◽  
Triboelectric Nanogenerator ◽  
Self Healing

The self-healing process and the primary characteristics showing the performance of the self-healed triboelectric nanogenerator.

scholarly journals Does a High Amount of Unhydrated Portland Cement Ensure an Effective Autogenous Self-Healing of Mortar?

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3298 ◽  
Author(s):  
Magdalena Rajczakowska ◽  
Lennart Nilsson ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Portland Cement ◽  
High Performance ◽  
Cement Content ◽  
Healing Process ◽  
Self Healing ◽  
Aging Effects ◽  
Cement Ratio ◽  
Dense Microstructure ◽  
Water To Cement Ratio ◽  
Very High

It is commonly accepted that the autogenous self-healing of concrete is mainly controlled by the hydration of Portland cement and its extent depends on the availability of anhydrous particles. High-performance (HPCs) and ultra-high performance concretes (UHPCs) incorporating very high amounts of cement and having a low water-to-cement ratio reach the hydration degree of only 70–50%. Consequently, the presence of a large amount of unhydrated cement should result in excellent autogenous self-healing. The main aim of this study was to examine whether this commonly accepted hypothesis was correct. The study included tests performed on UHPC and mortars with a low water-to-cement ratio and high cement content. Additionally, aging effects were verified on 12-month-old UHPC samples. Analysis was conducted on the crack surfaces and inside of the cracks. The results strongly indicated that the formation of a dense microstructure and rapidly hydrating, freshly exposed anhydrous cement particles could significantly limit or even hinder the self-healing process. The availability of anhydrous cement appeared not to guarantee development of a highly effective healing process.

scholarly journals Preparation and characterization of self-healing furan-terminated polybutadiene (FTPB) based on Diels–Alder reaction

RSC Advances ◽  
2021 ◽  
Vol 11 (51) ◽  
pp. 32369-32375
Author(s):  
Min Xia ◽  
Yanjie Zhang ◽  
Qing Na ◽  
Tao Guo ◽  
Minghao Zhang ◽  
...  
Keyword(s):  
Healing Process ◽  
Alder Reaction ◽  
Diels Alder ◽  
Self Healing ◽  
Diels Alder Reaction

Thermoreversible self-healing process of FTPB-DA.

Thermo-Responsive Shape Memory Self-Healing Polyurethanes and Composites With Continuous Carbon Fiber Reinforcement

2015 ◽  
Author(s):  
Yunseon Heo ◽  
Henry A. Sodano
Keyword(s):  
Carbon Fiber ◽  
Shape Memory ◽  
Variable Temperature ◽  
Healing Process ◽  
External Pressure ◽  
Diels Alder ◽  
Proton Nuclear Magnetic Resonance ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Continuous Carbon Fiber

Thermally responsive self-healing polyurethanes (1DA1T, 1.5DA1T, and 2DA1H) with shape memory property were developed and the fully reversible Diels-Alder (DA) and retro Diels-Alder (rDA) reactions were employed for the healing mechanism. The transition temperatures of the DA and rDA reactions were confirmed through a differential scanning calorimetry and the molecular level of analysis on the reversibility and the repeatability between the DA and rDA reactions were completed though a variable temperature proton nuclear magnetic resonance at the reaction temperatures. Also, compact tension specimens were made to observe the healing efficiencies. These specimens were healed without the use of external forces to close the crack surfaces after testing for the repeatable healing ability with three cycles. As a result, the average first healing cycle efficiencies of 80%, 84%, and 96% for 1DA1T, 1.5DA1T and 2DA1H, respectively, were achieved and small drops for the second and third healing cycles were observed. Then, using two of the self-healing polyurethanes as resins, continuous carbon fiber fabric reinforced polymer matrix composites (C1.5DA1T and C2DA1H) were fabricated and short beam shear testing was conducted to determine the healing capability on the delamination. Accordingly, the first healing efficiencies of 88% and 85% were measured without any additional treatments on the fibers; however, an external pressure was applied during the composite healing process.

scholarly journals Thermally Switchable Electrically Conductive Thermoset rGO/PK Self-Healing Composites

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 339
Author(s):  
Esteban Araya-Hermosilla ◽  
Alice Giannetti ◽  
Guilherme Macedo R. Lima ◽  
Felipe Orozco ◽  
Francesco Picchioni ◽  
...  
Keyword(s):  
Smart Materials ◽  
High Performance ◽  
Polymer Network ◽  
Conductive Polymer ◽  
Alder Reaction ◽  
Diels Alder ◽  
Self Healing ◽  
Stimuli Responsive ◽  
Electrically Conductive ◽  
Suitable Material

Among smart materials, self-healing is one of the most studied properties. A self-healing polymer can repair the cracks that occurred in the structure of the material. Polyketones, which are high-performance thermoplastic polymers, are a suitable material for a self-healing mechanism: a furanic pendant moiety can be introduced into the backbone and used as a diene for a temperature reversible Diels-Alder reaction with bismaleimide. The Diels-Alder adduct is formed at around 50 °C and broken at about 120 °C, giving an intrinsic, stimuli-responsive self-healing material triggered by temperature variations. Also, reduced graphene oxide (rGO) is added to the polymer matrix (1.6–7 wt%), giving a reversible OFF-ON electrically conductive polymer network. Remarkably, the electrical conductivity is activated when reaching temperatures higher than 100 °C, thus suggesting applications as electronic switches based on self-healing soft devices.

Sign in / Sign up

Export Citation Format

Share Document