SELF HEALING POTENTIAL OF GREEN NANOCOMPOSITES FROM CRYSTALLINE CELLULOSE

2011 ◽  
Vol 25 (31) ◽  
pp. 4216-4219 ◽  
Author(s):  
JITENDRA KUMAR PANDEY ◽  
HITOSHI TAKAGI
Keyword(s):  
Material Properties ◽  
High Performance ◽  
The Self ◽  
Cellulose Microfibrils ◽  
Crystalline Cellulose ◽  
Self Healing ◽  
Plant Cell Walls ◽  
Initial Stage ◽  
High Performance Polymer ◽  
Cellulose Fibrils

In plant cell walls, stiff semicrystalline nano dimensional cellulose microfibrils are embedded in a pliable amorphous matrix where the size and shape of the cellulose fibrils are controlled by the dimensions of crystalline regions, providing them a unique structural and physical combination to be applied as load-bearing constituent in composites. The qualities such as specific orientation under magnetic field, extraction through simple process, abundantly available source from nature and desirable modifications have deliberately directed the intense research efforts in a number of disciplines ranging from commodity to higher applications, not only in the area of high performance polymer based composites but also to develop biosensors, magnetic strips and optical devices. The present work is focused on the use of cellulose nano-fillers for creating the self-healing function and their effect on material properties of resulting composites. The present work is in initial stage and reviews the use of cellulose nano-fillers for creating the self-healing function and their effect on material properties of resulting composites.

scholarly journals Effect of crack pattern on the self-healing capability in traditional, HPC and UHPFRC concretes measured by water and chloride permeability

2019 ◽  
Vol 289 ◽  
pp. 01006 ◽  
Author(s):  
Alberto Negrini ◽  
Marta Roig-Flores ◽  
Eduardo J. Mezquida-Alcaraz ◽  
Liberato Ferrara ◽  
Pedro Serna
Keyword(s):  
Reinforced Concrete ◽  
Water Permeability ◽  
High Performance ◽  
Water Immersion ◽  
Crack Pattern ◽  
The Self ◽  
Reinforced Concrete Beams ◽  
Multiple Cracks ◽  
Self Healing ◽  
High Performance Fibre

Concrete has a natural self-healing capability to seal small cracks, named autogenous healing, which is mainly produced by continuing hydration and carbonation. This capability is very limited and is activated only when in direct contact with water. High Performance Fibre-Reinforced Concrete and Engineered Cementitious Composites have been reported to heal cracks for low damage levels, due to their crack pattern with multiple cracks and high cement contents. While their superior self-healing behaviour compared to traditional concrete types is frequently assumed, this study aims to have a direct comparison to move a step forward in durability quantification. Reinforced concrete beams made of traditional, high-performance and ultra-high-performance fibre-reinforced concretes were prepared, sized 150×100×750 mm3. These beams were pre-cracked in flexion up to fixed strain levels in the tensioned zone to allow the analysis of the effect of the different cracking patterns on the self-healing capability. Afterwards, water permeability tests were performed before and after healing under water immersion. A modification of the water permeability test was also explored using chlorides to evaluate the potential protection of this healing in chloride-rich environments. The results show the superior durability and self-healing performance of UHPFRC elements.

The effect of nanoparticles on the self-healing capacity of high performance concrete

2019 ◽  
pp. 43-67 ◽  
Author(s):  
J.L. García Calvo ◽  
G. Pérez ◽  
P. Carballosa ◽  
E. Erkizia ◽  
J.J. Gaitero ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
The Self ◽  
Self Healing

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 Experimental Study on the Self-Healing Behavior of Fractured Rocks Induced by Water-CO2-Rock Interactions in the Shendong Coalfield

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jinfeng Ju ◽  
Quansheng Li ◽  
Jialin Xu
Keyword(s):  
Clay Minerals ◽  
Water Permeability ◽  
Fractured Rocks ◽  
The Self ◽  
Coarse Grained ◽  
Ionic Exchange ◽  
Self Healing ◽  
Rock Interaction ◽  
Fine Grained ◽  
Initial Stage

This study experimentally investigated the self-healing behavior, referring to the naturally occurring water permeability decrease, of fractured rocks exposed to water-CO2-rock interaction (WCRI). The experiment was conducted on prefractured specimens of three rock types typical of the Shendong coalfield: coarse-grained sandrock, fine-grained sandrock, and sandy mudrock. During the experiment, which ran for nearly 15 months, all three specimens exhibited decreasing permeabilities. The coarse- and fine-grained sandrock specimens exhibited smooth decreases in permeability, with approximately parallel permeability time curves, whereas that of the sandy mudrock specimen decreased rapidly during the initial stage and slowly during later stages. The sandrock specimens were rich in feldspars, which were dissolved and/or corroded and involved in ionic exchange reactions with CO2 and groundwater, thereby generating secondary minerals (such as kaolinite, quartz, and sericite) or CaSO4 sediments. These derivative matters adhered to the fracture surface, thereby gradually repairing fractures and decreasing the water permeability of the fractured rocks. In comparison, the sandy mudrock had a high content of clay minerals, and the water-rock interaction caused rapid expansions of illite, mixed illite-smectite, and other clay minerals, thereby narrowing the fractures and causing the rapid permeability decrease during the initial stage. In later stages, the derivative matters generated by the dissolution and/or corrosion of feldspars and other aluminum silicate minerals in the mudrock filled and sealed the fractures, causing the slow permeability decreases during the later stages, as in the sandrock specimens. Neutral and basic groundwater conditions facilitated better self-healing of fractured mudrocks rich in clay minerals, whereas acidic groundwater conditions and the presence of CO2 facilitated better self-healing of fractured sandrocks. Thus, this study’s results are of significant value to aquifer restoration efforts in the Shendong coalfield and other ecologically vulnerable mining areas.

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