Self-healing dynamic bond-based rubbers: understanding the mechanisms in ionomeric elastomer model systems

2015 ◽  
Vol 17 (32) ◽  
pp. 21005-21017 ◽  
Author(s):  
N. Hohlbein ◽  
A. Shaaban ◽  
A. R. Bras ◽  
W. Pyckhout-Hintzen ◽  
A. M. Schmidt
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Model System ◽  
Model Systems ◽  
Time Dependent ◽  
Self Healing ◽  
Structure Property ◽  
Healing Efficiency ◽  
Oscillatory Rheology ◽  
Systematic Structure

Systematic structure-property investigations on the time-dependent mechanical properties of an ionomer model system with variation of the ionic fraction and the counter ion as obtained from SAXS, dynamic oscillatory rheology and tensile tests, deliver the prerequisites and tools for property adjustment and optimization of their self-healing efficiency.

scholarly journals Recyclable Self-Healing Polyurethane Cross-Linked by Alkyl Diselenide with Enhanced Mechanical Properties

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 773 ◽  
Author(s):  
Yuqing Qian ◽  
Xiaowei An ◽  
Xiaofei Huang ◽  
Xiangqiang Pan ◽  
Jian Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Amide Bond ◽  
Self Healing ◽  
Healing Efficiency ◽  
Polyurethane Networks ◽  
Combined Action ◽  
Cross Linker ◽  
Dynamic Structures ◽  
External Interventions

Dynamic structures containing polymers can behave as thermosets at room temperature while maintaining good mechanical properties, showing good reprocessability, repairability, and recyclability. In this work, alkyl diselenide is effectively used as a dynamic cross-linker for the design of self-healing poly(urea–urethane) elastomers, which show quantitative healing efficiency at room temperature, without the need for any catalysts or external interventions. Due to the combined action of the urea bond and amide bond, the material has better mechanical properties. We also compared the self-healing effect of alkyl diselenide-based polyurethanes and alkyl disulfide-based polyurethanes. The alkyl diselenide has been incorporated into polyurethane networks using a para-substituted amine diphenyl alkyl diselenide. The resulting materials not only exhibit faster self-healing properties than the corresponding disulfide-based materials, but also show the ability to be processed at temperatures as low as 60 °C.

scholarly journals Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Cementitious Materials ◽  
Self Healing ◽  
Negative Effects ◽  
Numerical Studies ◽  
Healing Efficiency ◽  
The Impact ◽  
Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

Additive manufacturing of ceramics: Present status and future perspectives

2021 ◽  
Author(s):  
Mainak Saha ◽  
Manab Mallik
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Microstructure Evolution ◽  
Review Article ◽  
Low Density ◽  
Structure Property ◽  
Future Perspectives ◽  
Structural Applications ◽  
Systematic Structure ◽  
State Of Research

At present, fabrication of ceramics using AM-based techniques mainly suffers from two primary limitations, viz: (i) low density and (ii) poor mechanical properties of the finished components. It is worth mentioning that the present state of research in the avenue of AM-based ceramics is focussed mainly on fabricating ceramic and cermet components with enhanced densities and improved mechanical properties. However, to the best of the authors’ knowledge, not much is known about the microstructure evolution and its correlation with the mechanical properties of the finished parts. Addressing the aforementioned avenue is highly essential for understanding the utilisation of these components for structural applications. To this end, the present review article is aimed to address the future perspectives in this avenue has been provided with a special emphasis on the need to establish a systematic structure-property correlation in these materials.

Additive manufacturing of ceramics and cermets: present status and future perspectives

2021 ◽  
Author(s):  
Mainak Saha ◽  
Manab Mallik
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Present Status ◽  
Interdisciplinary Research ◽  
Low Density ◽  
Metallic Materials ◽  
Structure Property ◽  
Future Perspectives ◽  
Present Decade ◽  
Systematic Structure

The present decade has witnessed a huge volume of research revolving around a number of Additive Manufacturing (AM) techniques, especially for the fabrication of different metallic materials. However, fabrication of ceramics and cermets using AM-based techniques mainly suffers from two primary limitations which are: (i) low density and (ii) poor mechanical properties of the final components. Although there has been a considerable volume of work on AM based techniques for manufacturing ceramic and cermet parts with enhanced densities and improved mechanical properties, however, there is limited understanding on the correlation of microstructure of AM-based ceramic and cermet components with the mechanical properties. The present article is aimed to review some of the most commonly used AM techniques for the fabrication of ceramics and cermets. This has been followed by a brief discussion on the microstructural developments during different AM-based techniques. In addition, an overview of the challenges and future perspectives, mainly associated with the necessity towards developing a systematic structure-property correlation in these materials has been provided based on three factors viz. the efficiency of different AM-based fabrication techniques (involved in ceramic and cermet research), an interdisciplinary research combining ceramic research with microstructural engineering and commercialisation of different AM techniques based on the authors’ viewpoints.

scholarly journals Dynamic Mussel-Inspired Chitin Nanocomposite Hydrogels for Wearable Strain Sensors

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1416 ◽  
Author(s):  
Pejman Heidarian ◽  
Abbas Z. Kouzani ◽  
Akif Kaynak ◽  
Ali Zolfagharian ◽  
Hossein Yousefi
Keyword(s):  
Mechanical Properties ◽  
Polyacrylic Acid ◽  
Strain Sensors ◽  
Self Healing ◽  
Network Stability ◽  
Ferric Ions ◽  
Trade Off ◽  
Nanocomposite Hydrogels ◽  
Healing Efficiency ◽  
Hydrogel Network

It is an ongoing challenge to fabricate an electroconductive and tough hydrogel with autonomous self-healing and self-recovery (SELF) for wearable strain sensors. Current electroconductive hydrogels often show a trade-off between static crosslinks for mechanical strength and dynamic crosslinks for SELF properties. In this work, a facile procedure was developed to synthesize a dynamic electroconductive hydrogel with excellent SELF and mechanical properties from starch/polyacrylic acid (St/PAA) by simply loading ferric ions (Fe3+) and tannic acid-coated chitin nanofibers (TA-ChNFs) into the hydrogel network. Based on our findings, the highest toughness was observed for the 1 wt.% TA-ChNF-reinforced hydrogel (1.43 MJ/m3), which is 10.5-fold higher than the unreinforced counterpart. Moreover, the 1 wt.% TA-ChNF-reinforced hydrogel showed the highest resistance against crack propagation and a 96.5% healing efficiency after 40 min. Therefore, it was chosen as the optimized hydrogel to pursue the remaining experiments. Due to its unique SELF performance, network stability, superior mechanical, and self-adhesiveness properties, this hydrogel demonstrates potential for applications in self-wearable strain sensors.

Adaptable Eu-containing polymeric films with dynamic control of mechanical properties in response to moisture

Soft Matter ◽  
2020 ◽  
Vol 16 (9) ◽  
pp. 2276-2284 ◽  
Author(s):  
Zichao Wei ◽  
Srinivas Thanneeru ◽  
Elena Margaret Rodriguez ◽  
Gengsheng Weng ◽  
Jie He
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Polymer Films ◽  
Dynamic Control ◽  
Polymeric Films ◽  
Self Healing ◽  
Healing Efficiency

Moisture that competes with dipicolylamine to bind Eu dynamically controls the mechanical and optical properties of polymer films, as well as their self-healing efficiency.

scholarly journals Internal and external catalysis in boronic ester networks

2021 ◽  
Author(s):  
Boyeong Kang ◽  
Julia Kalow
Keyword(s):  
Mechanical Properties ◽  
Binding Affinity ◽  
Polymer Networks ◽  
Model Systems ◽  
Self Healing ◽  
Dynamic Materials ◽  
Boronic Ester ◽  
Rate Acceleration ◽  
Exchange Spectroscopy ◽  
Kinetics Of

In dynamic materials, the reversible condensation between boronic acids and diols provides adaptability, self-healing ability, and responsiveness to small molecules and pH. Recent work has shown that the thermodynamics and kinetics of bond exchange determine the mechanical properties of dynamic polymer networks. However, prior studies have focused on how structural and environmental factors influence boronic acid–diol binding affinity, and design rules for tuning the kinetics of this dynamic bond are lacking. In this work, we investigate the effects of diol (or polyol) structure and salt additives on the rate of bond exchange, binding affinity, and the mechanical properties of the corresponding polymer networks. To better mimic the environment of polymer networks in our small-molecule model systems, we incorporated proximal amide groups, which are used to conjugate diols to polymers, and included salts commonly found in buffers. Using one-dimensional selective exchange spectroscopy (1D EXSY), we find that both proximal amides and buffering anions induce significant rate acceleration consistent with internal and external catalysis, respectively. This rate acceleration is reflected in the stress relaxation of gels formed using PEG modified with different alcohols, and in the presence of salts containing acetate or phosphate. These findings contribute to the fundamental understanding of the boronic ester dynamic bond and offer new molecular strategies to tune the macromolecular properties of dynamic materials.

Study on the Effects of the Self-Healing Microcapsules on the Tensile Properties of Polymer Composite

2011 ◽  
Vol 299-300 ◽  
pp. 460-465 ◽  
Author(s):  
Li Zhang ◽  
Xiu Ping Dong ◽  
Hao Chen
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Glass Fiber ◽  
Tensile Properties ◽  
Polymer Composite ◽  
Tensile Tests ◽  
The Self ◽  
Self Healing ◽  
Glass Fiber Reinforced

By designing different formulations of composites and adopting optimized technology including extrusion and molding, the different composites with various content microcapsules were prepared. The results of the tensile tests show that with the increasing content of self-healing microcapsules in the glass fiber reinforced nylon composites, the mechanical properties of the composites will change, i.e. tensile strength, elastic modulus will decrease. But there is little effect on the mechanical properties of the composite gears if the content of self-healing microcapsules is less than 3.5%, and the technology of self-healing microcapsules used in the polymer composite gear is feasible.

Soluble Silicates as Additives for Self-Sealing and Self-Healing Concrete

2016 ◽  
Vol 1813 ◽  
Author(s):  
L. E. Rendon Diaz Miron ◽  
M. E. Lara Magaña
Keyword(s):  
Mechanical Properties ◽  
Crack Formation ◽  
Healing Process ◽  
Self Healing ◽  
Reaction Products ◽  
Calcium Carbonate Precipitation ◽  
Broad Perspective ◽  
Healing Efficiency ◽  
Tensile Forces ◽  
Solubility Ratio

ABSTRACTTensile strength of concrete is limited and therefore is sensitive to crack formation. Steel reinforcement is added to bear the tensile forces; nonetheless, this does not completely omit crack formation. Repair of cracks in concrete is time-consuming and expensive. Self-sealing and self-healing of cracks upon appearance would therefore be a convenient property. We propose a mechanism to obtain self-repair of the concrete by adding soluble silicates (ASS) which will induce a self-sealing and self-healing process catalyzed by natural periods of wet and dry states of the concrete. Self-sealing approaches prevent the ingress of harsh chemical substances which may deteriorate the concrete matrix. This can be achieved by self-healing of concrete cracks (e.g. further cement hydration, calcium carbonate precipitation) and autonomous healing (e.g. further hydration of partially soluble silicates added as healing agents). The autogenous healing efficiency depends on the amount of deposited reaction products (ASS), its solubility (ratio of calcium to sodium silicate), the availability of water, and the crack width (restricted by adding microfibers). The self-sealing efficiency is generally evaluated by measuring the decrease in water permeability and air flow through the crack. The healing efficiency is usually evaluated by testing concrete´s regain in mechanical properties after crack formation; by reloading the cracked and autonomously healed specimen and comparing the obtained mechanical properties with the original ones. Self-sealing and self-healing of concrete gives a broad perspective and new possibilities to make future concrete structures more durable.

scholarly journals Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4164 ◽  
Author(s):  
Hayeon Kim ◽  
Hyeongmin Son ◽  
Joonho Seo ◽  
H. K. Lee
Keyword(s):  
Mechanical Properties ◽  
Mercury Intrusion Porosimetry ◽  
Tap Water ◽  
Bottom Ash ◽  
Self Healing ◽  
Mixing Process ◽  
Mercury Intrusion ◽  
Healing Efficiency ◽  
Cement Based Materials ◽  
Healing Agent

The present study evaluated the self-healing efficiency and mechanical properties of mortar specimens incorporating a bio-carrier as a self-healing agent. The bio-carrier was produced by immobilizing ureolytic bacteria isolated from seawater in bottom ash, followed by surface coating with cement powder to prevent loss of nutrients during the mixing process. Five types of specimens were prepared with two methods of incorporating bacteria, and were water cured for 28 days. To investigate the healing ratio, the specimens with predefined cracks were treated by applying a wet–dry cycle in three different conditions, i.e., seawater, tap water, and air for 28 days. In addition, a compression test and a mercury intrusion porosimetry analysis of the specimens were performed to evaluate their physico-mechanical properties. The obtained results showed that the specimen incorporating the bio-carrier had higher compressive strength than the specimen incorporating vegetative cells. Furthermore, the highest healing ratio was observed in specimens incorporating the bio-carrier. This phenomenon could be ascribed by the enhanced bacterial viability by the bio-carrier.

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