scholarly journals Restoration of tensile strength in bark samples of Ficus benjamina due to coagulation of latex during fast self-healing of fissures

2011 ◽  
Vol 109 (4) ◽  
pp. 807-811 ◽  
Author(s):  
Georg Bauer ◽  
Thomas Speck
Keyword(s):  
Tensile Strength ◽  
Self Healing ◽  
Ficus Benjamina

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.

scholarly journals A Robust, Tough and Multifunctional Polyurethane/Tannic Acid Hydrogel Fabricated by Physical-Chemical Dual Crosslinking

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 239 ◽  
Author(s):  
Jie Wen ◽  
Xiaopeng Zhang ◽  
Mingwang Pan ◽  
Jinfeng Yuan ◽  
Zhanyu Jia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Polyethylene Glycol ◽  
Hydrogen Bonds ◽  
Tannic Acid ◽  
Hydroxyl Groups ◽  
Self Healing ◽  
Physical Chemical ◽  
Biomedical Field ◽  
Physical Crosslinking

Commonly synthetic polyethylene glycol polyurethane (PEG–PU) hydrogels possess poor mechanical properties, such as robustness and toughness, which limits their load-bearing application. Hence, it remains a challenge to prepare PEG–PU hydrogels with excellent mechanical properties. Herein, a novel double-crosslinked (DC) PEG–PU hydrogel was fabricated by combining chemical with physical crosslinking, where trimethylolpropane (TMP) was used as the first chemical crosslinker and polyphenol compound tannic acid (TA) was introduced into the single crosslinked PU network by simple immersion process. The second physical crosslinking was formed by numerous hydrogen bonds between urethane groups of PU and phenol hydroxyl groups in TA, which can endow PEG–PU hydrogel with good mechanical properties, self-recovery and a self-healing capability. The research results indicated that as little as a 30 mg·mL−1 TA solution enhanced the tensile strength and fracture energy of PEG–PU hydrogel from 0.27 to 2.2 MPa, 2.0 to 9.6 KJ·m−2, respectively. Moreover, the DC PEG–PU hydrogel possessed good adhesiveness to diverse substrates because of TA abundant catechol groups. This work shows a simple and versatile method to prepare a multifunctional DC single network PEG–PU hydrogel with excellent mechanical properties, and is expected to facilitate developments in the biomedical field.

scholarly journals Self-Healable Supramolecular Vanadium Pentoxide Reinforced Polydimethylsiloxane-Graft-Polyurethane Composites

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 41 ◽  
Author(s):  
Ali Berkem ◽  
Ahmet Capoglu ◽  
Turgut Nugay ◽  
Erol Sancaktar ◽  
Ilke Anac
Keyword(s):  
Tensile Strength ◽  
Vanadium Pentoxide ◽  
Coupling Reaction ◽  
Optical Microscope ◽  
Mechanical Tests ◽  
Healing Time ◽  
The Self ◽  
Supramolecular Polymer ◽  
Self Healing ◽  
Healing Efficiency

The self-healing ability can be imparted to the polymers by different mechanisms. In this study, self-healing polydimethylsiloxane-graft-polyurethane (PDMS-g-PUR)/Vanadium pentoxide (V2O5) nanofiber supramolecular polymer composites based on a reversible hydrogen bonding mechanism are prepared. V2O5 nanofibers are synthesized via colloidal route and characterized by XRD, SEM, EDX, and TEM techniques. In order to prepare PDMS-g-PUR, linear aliphatic PUR having one –COOH functional group (PUR-COOH) is synthesized and grafted onto aminopropyl functionalized PDMS by EDC/HCl coupling reaction. PUR-COOH and PDMS-g-PUR are characterized by 1H NMR, FTIR. PDMS-g-PUR/V2O5 nanofiber composites are prepared and characterized by DSC/TGA, FTIR, and tensile tests. The self-healing ability of PDMS-graft-PUR and composites are determined by mechanical tests and optical microscope. Tensile strength data obtained from mechanical tests show that healing efficiencies of PDMS-g-PUR increase with healing time and reach 85.4 ± 1.2 % after waiting 120 min at 50 °C. The addition of V2O5 nanofibers enhances the mechanical properties and healing efficiency of the PDMS-g-PUR. An increase of healing efficiency and max tensile strength from 85.4 ± 1.2% to 95.3 ± 0.4% and 113.08 ± 5.24 kPa to 1443.40 ± 8.96 kPa is observed after the addition of 10 wt % V2O5 nanofiber into the polymer.

Self-Healing Glass Fibres with Carbon Nanotube-Epoxy Nanocomposite Coating

2007 ◽  
Vol 334-335 ◽  
pp. 805-808 ◽  
Author(s):  
Naveed A. Siddiqui ◽  
Jang Kyo Kim ◽  
Farjaad Muzaffar ◽  
Arshad Munir
Keyword(s):  
Tensile Strength ◽  
Carbon Nanotube ◽  
Strength Distribution ◽  
Neat Epoxy ◽  
Self Healing ◽  
Stress Concentrations ◽  
Clear Trend ◽  
Epoxy Nanocomposite ◽  
Glass Fibres ◽  
The Individual

This paper reports a study based on a novel concept of ‘self-healing’ coatings applied onto the brittle fibre surface to reduce the stress concentrations and thus to improve the reinforcing efficiency in a composite. The individual E-glass fibres as well as rovings were coated with a carbon nanotube (CNT) reinforced epoxy composite. The tensile strengths were measured for the individual and bundle fibres, which were treated statistically to determine the Weibull parameters and thus to evaluate the notch sensitivity of the fibres with and without coating. The results indicate that the tensile strength of the individual fibre increased by 10% after coating with neat epoxy. Coating with epoxy nanocomposite containing 0.3wt% MWNT further improved the tensile strength. However, increasing the nanotube content was not necessarily beneficial due to the formation of nanotube agglomerates within the matrix. The tensile tests on fibre roving also showed a clear trend of beneficial effect of nanocomposite impregnation on tensile strength. The rovings impregnated with nanocomposite exhibited a more uniform strength distribution and higher strengths than those impregnated with neat epoxy. Changes in prevailing failure mechanisms influenced by the epoxy and nanocomposite coatings are identified.

scholarly journals Achievement of Both Mechanical Properties and Intrinsic Self-Healing under Body Temperature in Polyurethane Elastomers: A Synthesis Strategy from Waterborne Polymers

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 989 ◽  
Author(s):  
Liangdong Zhang ◽  
Teng Qiu ◽  
Xiting Sun ◽  
Longhai Guo ◽  
Lifan He ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Body Temperature ◽  
Healing Process ◽  
Waterborne Polyurethane ◽  
Polymer Materials ◽  
Self Healing ◽  
Polyurethane Elastomers ◽  
Elongation At Break ◽  
Synthesis Strategy ◽  
A Chain

Inspired by the growing demand for smart and environmentally friendly polymer materials, we employed 2,2′-disulfanediyldianiline (22DTDA) as a chain extender to synthesize a waterborne polyurethane (WPUR). Due to the ortho-substituted structure of the aromatic disulfide, the urea moieties formed a unique microphase structure in the WPUR, its mechanical strength was enhanced more 180 times relative to that of the material prepared without 22DTDA, and excellent self-healing abilities at body temperature in air or under ultrasound in water were obtained. If the self-healing process was carried out at 37 °C, 50 °C or under ultrasound, the ultimate tensile strength and elongation at break of the healed film could reach 13.8 MPa and 1150%, 15.4 MPa and 1215%, or 16 MPa and 1056%, respectively. Moreover, the WPUR films could be re-healed at the same fracture location over three cutting–healing cycles, and the recovery rates of the tensile strength and elongation at break remained almost constant throughout these cycles.

scholarly journals Characteristics of Self-Healable Copolymers of Styrene and Eugenol Terminated Polyurethane Prepolymer

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1674 ◽  
Author(s):  
Jing-Yu Liang ◽  
Se-Ra Shin ◽  
Soo-Hyoung Lee ◽  
Dai-Soo Lee
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fossil Fuel ◽  
Renewable Resource ◽  
Self Healing ◽  
Elongation At Break ◽  
Good Thermal Stability ◽  
Healing Property ◽  
Polyurethane Prepolymer ◽  
Reversible Nature

With limited biomass that can be currently utilized as a renewable resource, it is important to develop a method to convert biomass into materials that can replace fossil fuel product. In this paper, eugenol, a bio-based allyl chain-substituted guaiacol, was used to synthesize self-healable copolymers. Eugenol terminated polyurethane prepolymer (ETPU) was synthesized from eugenol and polyurethane prepolymers terminated with isocyanate groups. ETPU contained two allyl groups. Self-healing copolymer networks were obtained by copolymerization of ETPU and styrene monomer via free radical polymerization. Effects of ETPU content on the properties of copolymers were then studied. These copolymers containing ETPU exhibited good thermal stability and mechanical properties. These copolymers showed higher tensile strength and elongation at break than PS. Their maximum tensile strength reached 19 MPa. In addition, these copolymers showed self-healing property at elevated temperature due to the reversible nature of urethane units in ETPU.

Effect of cross-link density and the healing efficiency of self-healing poly(2-hydroxyethyl methacrylate) hydrogel

e-Polymers ◽  
2014 ◽  
Vol 14 (4) ◽  
pp. 289-294 ◽  
Author(s):  
Najiyyah Abdullah Sirajuddin ◽  
Mohd Suzeren Md Jamil ◽  
Muhammad Azwani Shah Mat Lazim
Keyword(s):  
Tensile Strength ◽  
Self Healing ◽  
Hydroxyethyl Methacrylate ◽  
Cross Link ◽  
Healing Efficiency ◽  
Link Density ◽  
Cross Link Density ◽  
Cross Linker ◽  
Chain Slippage ◽  
Polymerization Method

AbstractIn this study, hydrogels of poly(2-hydroxyethyl methacrylate) with different cross-link density were prepared by the free-radical polymerization method. l-Cystine, which acts as a cross-linker, was prepared at different concentrations, ranging from 0.02 to 0.08 mol/l, to identify the concentration that provided the highest mechanical strength and healing efficacy. Healing of the hydrogels was achieved by heating above their glass transition temperature. Intermolecular diffusion of the dangling chain or chain slippage led to the healing of the gels. Results showed that 0.04 mol/l of l-cystine in poly(2-hydroxyethyl methacrylate) hydrogels provided the highest ultimate tensile strength (0.780 N/mm2) and healing recovery (92%). This healing capability was also observed using optical microscopy.

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.

An autonomous self-healing hydrogel with high polydopamine content for improved tensile strength

2020 ◽  
Vol 55 (36) ◽  
pp. 17255-17265
Author(s):  
Jinxin Huang ◽  
Wei Zhang ◽  
Heng Li ◽  
Xiaogang Yu ◽  
Shuaiwen Ding ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Self Healing

scholarly journals Self-healable, tough and highly stretchable hydrophobic association/ionic dual physically cross-linked hydrogels

RSC Advances ◽  
2017 ◽  
Vol 7 (20) ◽  
pp. 12063-12073 ◽  
Author(s):  
Yulin Zhang ◽  
Chengxin Hu ◽  
Xu Xiang ◽  
Yongfu Diao ◽  
Binwei Li ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Hydrophobic Association ◽  
Self Healing ◽  
Highly Stretchable ◽  
Novel Method

In this work, we describe a novel method for the production of tough and highly stretchable hydrogels with self-healing behavior, tensile strength of 150–300 kPa and stretch at break of 2400–2800%.

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