Self-Healing of Mechanical Properties: Evaluation by Tensile Testing

We designed a novel polyisoprene elastomer with high mechanical properties and autonomous self-healing capability at room temperature facilitated by the coexistence of dynamic ionic crosslinks and crystalline components that slowly reassembled.

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Polypyrrole/PU hybrid hydrogels: electrically conductive and fast self-healing for the potential application in body-monitor sensor

New Journal of Chemistry ◽

10.1039/d1nj00616a ◽

2021 ◽

Author(s):

Zhanyu Jia ◽

Guangyao Li ◽

Juan Wang ◽

shouhua Su ◽

Jie Wen ◽

...

Keyword(s):

Mechanical Properties ◽

Electrical Conductivity ◽

Potential Application ◽

Self Healing ◽

Electrically Conductive ◽

Sensor Application ◽

Hybrid Hydrogels ◽

Health Monitor

Conductivity, self-healing and moderate mechanical properties are necessary for multifunctional hydrogels which have great potential in health-monitor sensor application. However, the combination of electrical conductivity, self-healing and good mechanical properties...

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Self-healing, Highly Elastic and Amphiphilic Silicone-based Polyurethane for Antifouling Coatings

Journal of Materials Chemistry B ◽

10.1039/d0tb02465a ◽

2021 ◽

Author(s):

Xiaobin Lin ◽

Qingyi Xie ◽

Chunfeng Ma ◽

Guangzhao Zhang

Keyword(s):

Mechanical Properties ◽

Silicone Elastomer ◽

Self Healing ◽

Fouling Resistance ◽

The Poor ◽

Antifouling Coatings ◽

Fouling Release

Silicone elastomer coatings have attracted increasing attention owing to its eco-friendly nature, excellent fouling release ability and drag-reducing property. However, the poor mechanical properties and lack of fouling resistance limits...

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Influence of Post Weld Heat Treatment on the Grain Size, and Mechanical Properties of the Alloy-800H Rotary Friction Weld Joints

Materials ◽

10.3390/ma14164366 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4366

Author(s):

Saqib Anwar ◽

Ateekh Ur Rehman ◽

Yusuf Usmani ◽

Ali M. Al-Samhan

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Grain Size ◽

Heat Affected Zone ◽

Tensile Testing ◽

Weld Zone ◽

Alloy 800H ◽

Weld Joints ◽

Heat Treated ◽

Friction Weld

This study evaluated the microstructure, grain size, and mechanical properties of the alloy 800H rotary friction welds in as-welded and post-weld heat-treated conditions. The standards for the alloy 800H not only specify the composition and mechanical properties but also the minimum grain sizes. This is because these alloys are mostly used in creep resisting applications. The dynamic recrystallization of the highly strained and plasticized material during friction welding resulted in the fine grain structure (20 ± 2 µm) in the weld zone. However, a small increase in grain size was observed in the heat-affected zone of the weldment with a slight decrease in hardness compared to the base metal. Post-weld solution heat treatment (PWHT) of the friction weld joints increased the grain size (42 ± 4 µm) in the weld zone. Both as-welded and post-weld solution heat-treated friction weld joints failed in the heat-affected zone during the room temperature tensile testing and showed a lower yield strength and ultimate tensile strength than the base metal. A fracture analysis of the failed tensile samples revealed ductile fracture features. However, in high-temperature tensile testing, post-weld solution heat-treated joints exhibited superior elongation and strength compared to the as-welded joints due to the increase in the grain size of the weld metal. It was demonstrated in this study that the minimum grain size requirement of the alloy 800H friction weld joints could be successfully met by PWHT with improved strength and elongation, especially at high temperatures.

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Effects of Microwave Treatment in Immersed Conditions on the Mechanical Properties of Jute Yarn

Fibers ◽

10.3390/fib9070040 ◽

2021 ◽

Vol 9 (7) ◽

pp. 40

Author(s):

Felicia Syrén ◽

Joel Peterson ◽

Nawar Kadi

Keyword(s):

Mechanical Properties ◽

Tensile Testing ◽

Glass Fibers ◽

Microwave Treatment ◽

Environmental Benefits ◽

Treatment Result ◽

Bast Fiber ◽

Fiber Properties ◽

Yarn Thickness ◽

Jute Yarn

The versatile bast fiber jute has environmental benefits compared to glass fibers. However, for jute to be used in a composite, the fiber properties need to be altered. This study aims to improve the mechanical properties of jute yarn to make it more suitable for technical applications as a composite. To alter its mechanical properties, jute yarn was immersed in water during microwave treatment. The time and power of the microwave settings differed between runs. Two states of the yarn were tested: fastened and un-fastened. Tensile testing was used at the yarn and fiber level, followed by Fourier-transform infrared spectroscopy (FTIR) and microscopy. The treatment result demonstrated the ability to increase the elongation of the jute yarn by 70%. The tenacity was also increased by 34% in the fastened state and 20% in the un-fastened state. FTIR showed that no change in the molecular structure occurred. The treatments resulted in a change of yarn thickness depending on the state of the yarn. The results indicate that microwave treatment can be used to make jute more suitable for technical applications depending on the microwave treatment parameters.

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The preparation of hydrogels with highly efficient self-healing and excellent mechanical properties

Journal of Molecular Liquids ◽

10.1016/j.molliq.2021.115581 ◽

2021 ◽

Vol 329 ◽

pp. 115581

Author(s):

Chaoxian Chen ◽

Zhongcun Li ◽

Siwen Chen ◽

Lingzhi Kong ◽

Zhihao Guo ◽

...

Keyword(s):

Mechanical Properties ◽

Self Healing ◽

Highly Efficient

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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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Mechanical properties of low-density paper

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2019-0052 ◽

2020 ◽

Vol 35 (1) ◽

pp. 61-70

Author(s):

Na Young Park ◽

Young Chan Ko ◽

Lili Melani ◽

Hyoung Jin Kim

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Structural Change ◽

Tensile Testing ◽

Tensile Modulus ◽

Gauge Length ◽

Efficiency Factor ◽

Low Density ◽

Tensile Stiffness ◽

Lower Tensile Strength

AbstractFor the mechanical properties of paper, tensile testing has been widely used. Among the tensile properties, the tensile stiffness has been used to determine the softness of low-density paper. The lower tensile stiffness, the greater softness of paper. Because the elastic region may not be clearly defined in a load-elongation curve, it is suggested to use the tensile modulus which is defined as the slope between the two points in the curve. The two points which provide the best correlation with subjective softness evaluation should be selected. Low-density paper has a much lower tensile strength, but much larger elongation at the break. It undergoes a continuous structural change during mechanical testing. The degree of the structural change should depend on tensile conditions such as the sample size, the gauge length, and the rate of elongation. For low-density paper, the tensile modulus and the tensile strength should be independent of each other. The structure efficiency factor (SEF) is defined as a ratio of the tensile strength to the tensile modulus and it may be used a guideline in developing superior low-density paper products.

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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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