Self-healing efficiency and crack closure of smart cementitious composite with crystalline admixture and structural polyurethane

From the perspective of improving the self-healing method in construction, a tubular healing fiber was adopted as a container to improve the encapsulation capacity, which was available using a micro-capsule as a container. Knowing the direction of the stresses to which structure members are subjected, this research investigated the influence of aligning tubular healing fibers parallel to intended stress into a cementitious composite to increase the self-healing capability. For that, a healing agent was encapsulated into a tubular healing fiber made with polyvinylidene of fluoride resin (PVDF). Then, the healing fiber was combined with steel fibers to align both fibers together parallel to the direction of an intended splitting tensile stress when subjected to a magnetic field in a cylindrical cementitious composite. The alignment method and the key point through which the alignment of the healing fibers could efficiently improve autonomic self-healing were investigated. Since the magnetic field is known to be able to drag steel to an expected direction, steel fibers were combined with the healing fibers to form a hybrid fiber that aligned both fibers together. The required mixture workability was investigated to avoid the sinking of the healing fibers into the mixture. The healing efficiency, according to the orientation of the healing fibers in the composite matrix, was evaluated through a permeability test and a repetitive splitting tensile test. The aligned healing fibers performed better than the randomly distributed healing fibers. However, according to the healing efficiency with aligned healing fibers, it was deduced that the observed decreasing effect of the container’s alignment on the specimen’s mechanical properties was low enough to be neglected.

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A MICROCAPSULE TECHNOLOGY BASED SELF-HEALING SYSTEM FOR CONCRETE STRUCTURES

Journal of Earthquake and Tsunami ◽

10.1142/s1793431113500140 ◽

2013 ◽

Vol 07 (03) ◽

pp. 1350014 ◽

Cited By ~ 12

Author(s):

BIQIN DONG ◽

NINGXU HAN ◽

MING ZHANG ◽

XIANFENG WANG ◽

HONGZHI CUI ◽

...

Keyword(s):

Urea Formaldehyde ◽

Concrete Structures ◽

The Self ◽

Polymerization Reaction ◽

Formaldehyde Resin ◽

Self Healing ◽

Cementitious Composite ◽

Healing System ◽

Healing Efficiency ◽

Healing Agent

In the study, a novel microcapsule technology based self-healing system for concrete structures has been developed. Through situ-polymerization reaction, the microcapsule is formed by urea formaldehyde resin to pack the epoxy material, which is applied to cementitious composite to achieve self-healing effect. The experimental results revealed that the self-healing efficiency of the composite can be accessed from the recovery of the permeability and strength for the cracked cementitious specimens as the healing agent in the microcapsule acting on the cracks directly. Scanning electronic microscope (SEM/EDX) results show that the epoxy resin is released along with the cracking of the cementitious composite and prevent from cracks continued growth. Further studies show that the self-healing efficiency is affected by the pre-loading of composite, particle size of microcapsule, aging duration of healing agent and so on.

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Ultrarobust, tough and highly stretchable self-healing materials based on cartilage-inspired noncovalent assembly nanostructure

Nature Communications ◽

10.1038/s41467-021-21577-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yuyan Wang ◽

Xin Huang ◽

Xinxing Zhang

Keyword(s):

Spider Silk ◽

Self Healing ◽

High Toughness ◽

Healing Efficiency ◽

Strong Interfacial Interaction ◽

Highly Stretchable ◽

Noncovalent Bonds ◽

Actuation Devices ◽

Noncovalent Bonding ◽

Polyurethane Matrix

AbstractSelf-healing materials integrated with excellent mechanical strength and simultaneously high healing efficiency would be of great use in many fields, however their fabrication has been proven extremely challenging. Here, inspired by biological cartilage, we present an ultrarobust self-healing material by incorporating high density noncovalent bonds at the interfaces between the dentritic tannic acid-modified tungsten disulfide nanosheets and polyurethane matrix to collectively produce a strong interfacial interaction. The resultant nanocomposite material with interwoven network shows excellent tensile strength (52.3 MPa), high toughness (282.7 MJ m‒3, which is 1.6 times higher than spider silk and 9.4 times higher than metallic aluminum), high stretchability (1020.8%) and excellent healing efficiency (80–100%), which overturns the previous understanding of traditional noncovalent bonding self-healing materials where high mechanical robustness and healing ability are mutually exclusive. Moreover, the interfacical supramolecular crosslinking structure enables the functional-healing ability of the resultant flexible smart actuation devices. This work opens an avenue toward the development of ultrarobust self-healing materials for various flexible functional devices.

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Rationally Constructed Surface Energy and Dynamic Hard Domains Balance Mechanical Strength and Self-Healing Efficiency of Energetic Linear Polymer Materials

Langmuir ◽

10.1021/acs.langmuir.1c00939 ◽

2021 ◽

Author(s):

Shanjun Ding ◽

Jun Zhang ◽

Guocui Zhu ◽

Xin Ren ◽

Lin Zhou ◽

...

Keyword(s):

Surface Energy ◽

Mechanical Strength ◽

Linear Polymer ◽

Polymer Materials ◽

Self Healing ◽

Healing Efficiency

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The Effect of Superabsorbent Polymers on the Microstructure and Self-Healing Properties of Cementitious-Based Composite Materials

Applied Sciences ◽

10.3390/app11020700 ◽

2021 ◽

Vol 11 (2) ◽

pp. 700

Author(s):

Irene A. Kanellopoulou ◽

Ioannis A. Kartsonakis ◽

Costas A. Charitidis

Keyword(s):

Mechanical Properties ◽

Composite Materials ◽

Hybrid Structure ◽

The Self ◽

Self Healing ◽

Cementitious Composite ◽

Superabsorbent Polymers ◽

Porosity Reduction ◽

Environment Control ◽

The Impact

Cementitious structures have prevailed worldwide and are expected to exhibit further growth in the future. Nevertheless, cement cracking is an issue that needs to be addressed in order to enhance structure durability and sustainability especially when exposed to aggressive environments. The purpose of this work was to examine the impact of the Superabsorbent Polymers (SAPs) incorporation into cementitious composite materials (mortars) with respect to their structure (hybrid structure consisting of organic core—inorganic shell) and evaluate the microstructure and self-healing properties of the obtained mortars. The applied SAPs were tailored to maintain their functionality in the cementitious environment. Control and mortar/SAPs specimens with two different SAPs concentrations (1 and 2% bwoc) were molded and their mechanical properties were determined according to EN 196-1, while their microstructure and self-healing behavior were evaluated via microCT. Compressive strength, a key property for mortars, which often degrades with SAPs incorporation, in this work, practically remained intact for all specimens. This is coherent with the porosity reduction and the narrower range of pore size distribution for the mortar/SAPs specimens as determined via microCT. Moreover, the self-healing behavior of mortar-SAPs specimens was enhanced up to 60% compared to control specimens. Conclusively, the overall SAPs functionality in cementitious-based materials was optimized.

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Intrinsic Self-Healing Epoxies in Polymer Matrix Composites (PMCs) for Aerospace Applications

Polymers ◽

10.3390/polym13020201 ◽

2021 ◽

Vol 13 (2) ◽

pp. 201

Author(s):

Stefano Paolillo ◽

Ranjita K. Bose ◽

Marianella Hernández Santana ◽

Antonio M. Grande

Keyword(s):

High Performance ◽

Polymer Matrix Composites ◽

Critical Issue ◽

General Description ◽

Self Healing ◽

Matrix Composites ◽

Testing Procedures ◽

Aerospace Applications ◽

Polymer Properties ◽

Healing Efficiency

This article reviews some of the intrinsic self-healing epoxy materials that have been investigated throughout the course of the last twenty years. Emphasis is placed on those formulations suitable for the design of high-performance composites to be employed in the aerospace field. A brief introduction is given on the advantages of intrinsic self-healing polymers over extrinsic counterparts and of epoxies over other thermosetting systems. After a general description of the testing procedures adopted for the evaluation of the healing efficiency and the required features for a smooth implementation of such materials in the industry, different self-healing mechanisms, arising from either physical or chemical interactions, are detailed. The presented formulations are critically reviewed, comparing major strengths and weaknesses of their healing mechanisms, underlining the inherent structural polymer properties that may affect the healing phenomena. As many self-healing chemistries already provide the fundamental aspects for recyclability and reprocessability of thermosets, which have been historically thought as a critical issue, perspective trends of a circular economy for self-healing polymers are discussed along with their possible advances and challenges. This may open up the opportunity for a totally reconfigured landscape in composite manufacturing, with the net benefits of overall cost reduction and less waste. Some general drawbacks are also laid out along with some potential countermeasures to overcome or limit their impact. Finally, present and future applications in the aviation and space fields are portrayed.

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

Polymers ◽

10.3390/polym11050773 ◽

2019 ◽

Vol 11 (5) ◽

pp. 773 ◽

Cited By ~ 3

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.

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Self-healing poly(siloxane-urethane) elastomers with remoldability, shape memory and biocompatibility

Polymer Chemistry ◽

10.1039/c6py01499b ◽

2016 ◽

Vol 7 (47) ◽

pp. 7278-7286 ◽

Cited By ~ 63

Author(s):

Jian Zhao ◽

Rui Xu ◽

Gaoxing Luo ◽

Jun Wu ◽

Hesheng Xia

Keyword(s):

Mechanical Property ◽

Shape Memory ◽

Microphase Separation ◽

Diels Alder ◽

Good Mechanical Property ◽

Self Healing ◽

Healing Efficiency ◽

Good Biocompatibility

The poly(siloxane-urethane) elastomers with microphase separation structure and Diels–Alder bonds show high healing efficiency, good mechanical property and good biocompatibility.

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

Advances in Materials Science and Engineering ◽

10.1155/2016/8271214 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 1

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.

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Mechanical responses of microencapsulated self-healing cementitious composites under compressive loading based on a micromechanical damage-healing model

International Journal of Damage Mechanics ◽

10.1177/10567895211011239 ◽

2021 ◽

pp. 105678952110112

Author(s):

Kaihang Han ◽

Jiann-Wen Woody Ju ◽

Yinghui Zhu ◽

Hao Zhang ◽

Tien-Shu Chang ◽

...

Keyword(s):

Fracture Toughness ◽

Compressive Strength ◽

Micromechanical Model ◽

Cementitious Composites ◽

Self Healing ◽

Damage Degree ◽

Healing Efficiency ◽

The Matrix ◽

Healing Agent ◽

Damage Healing

The cementitious composites with microencapsulated healing agents have become a class of hotspots in the field of construction materials, and they have very broad application prospects and research values. The in-depth study on multi-scale mechanical behaviors of microencapsulated self-healing cementitious composites is critical to quantitatively account for the mechanical response during the damage-healing process. This paper proposes a three-dimensional evolutionary micromechanical model to quantitatively explain the self-healing effects of microencapsulated healing agents on the damage induced by microcracks. By virtue of the proposed 3 D micromechanical model, the evolutionary domains of microcrack growth (DMG) and corresponding compliances of the initial, extended and repaired phases are obtained. Moreover, the elaborate studies are conducted to inspect the effects of various system parameters involving the healing efficiency, fracture toughness and preloading-induced damage degrees on the compliances and stress-strain relations. The results indicate that relatively significant healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will lead to a higher compressive strength and stiffness. However, the specimen will break owing to the nucleated microcracks rather than the repaired kinked microcracks. Further, excessive higher values of healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will not affect the compressive strength of the cementitious composites. Therefore, a stronger matrix is required. To achieve the desired healing effects, the specific parameters of both the matrix and microcapsules should be selected prudently.

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