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Self Healing Polymer
Jayanta Saha
M.Sc.
2015CHS1003
1
2
The different strategies of designing self-healing materials are as follows:
• release of healing agent
• reversible cro...
Strategies of self healing materials
Hollow fiber repair mechanism.
Microencapsulated healing agent.
Micro vascular net...
4
Hollow fiber repair mechanism
Hollow fiber repair mechanism
5
6
Hollow glass fiber repair mechanism
7
 When DCPD comes into contact with the Grubbs’
catalyst dispersed in the epoxy resin a ring opening
metathesis polymeri...
8
MICROENCAPSULATION:
This area of interest is based upon a biological ‘bleeding’ approach to
repair,
9
Microencapsulation self-healing involves
the use of a monomer, (DCPD), stored in
urea-formaldehyde microcapsules disper...
10
MICROENCAPSULATION:
When the microcapsules are ruptured
by a crack, the monomer is comes into
contact with a dispersed...
11
Microvascular System
To overcome the difficulty of
short supply of a healing agent
in microcapsule-based self-
healing ...
12
Microvascular System
13
Reversible Cross-links
 Cross-linking is an irreversible process, which gives superior mechanical properties
 highly ...
14
Diels–Alder (DA) and Retro-DA Reactions
Major classes of thermally reversible polymers are made using Diels–Alder (DA) ...
15
Diels–Alder (DA) and Retro-DA Reactions
16
Ionomers
 Ionomers are a special class of polymeric materials that contain a hydrocarbon backbone and
pendent acid gro...
17
In particular, the self-healing ability of poly(ethyleneco methacrylic acid) (EMAA)-based ionomers
18
Supramolecular Polymers
Recently, low molar mass monomers are assembled together by reversible noncovalent
interactions...
19
Photographs showing thermally reversible cross-linking
behavior of PA-MI/TF polymers (PA-MI-1/TF polymers
have lowest c...
Applications
20
21
self healing paint
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Next Generation Self-Healing Concrete:
♜Microbial Induced Calcium
Carbonate Precipitation (MICCP)
♜Urease: (CO(NH2)2) ...
23
The composite material is made
from hollow fibers filled with epoxy
resin. When a hole or crack
appears, the resin leak...
24
25
When the concrete is mixed with bacteria (bacillus subtilus), the bacteria go into a dormant state, a lot like seeds. A...
26
3
The bacteria can thus act as a nucleation site which facilitates in the precipitation of calcite which can eventually...
27
28
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Self healing polymer

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Self healing polymer

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Self healing polymer

  1. 1. Self Healing Polymer Jayanta Saha M.Sc. 2015CHS1003 1
  2. 2. 2 The different strategies of designing self-healing materials are as follows: • release of healing agent • reversible cross-links Self Healing Polymer Self-healing materials are a class of smart materials that have the structurally incorporated ability to repair damage caused by mechanical usage over time. The inspiration comes from biological systems, which have the ability to heal after being wounded.
  3. 3. Strategies of self healing materials Hollow fiber repair mechanism. Microencapsulated healing agent. Micro vascular network. 3
  4. 4. 4 Hollow fiber repair mechanism
  5. 5. Hollow fiber repair mechanism 5
  6. 6. 6 Hollow glass fiber repair mechanism
  7. 7. 7  When DCPD comes into contact with the Grubbs’ catalyst dispersed in the epoxy resin a ring opening metathesis polymerization (ROMP) starts and a highly cross-linked tough polycyclopendiene is formed that seals the crack Polymer Engineering and Science, 46, 1804–11 Hollow fiber repair mechanism
  8. 8. 8 MICROENCAPSULATION: This area of interest is based upon a biological ‘bleeding’ approach to repair,
  9. 9. 9 Microencapsulation self-healing involves the use of a monomer, (DCPD), stored in urea-formaldehyde microcapsules dispersed within a polymer matrix. MICROENCAPSULATION:
  10. 10. 10 MICROENCAPSULATION: When the microcapsules are ruptured by a crack, the monomer is comes into contact with a dispersed particulate catalyst, thus initiating polymerization & repair. M. Scheiner et al. / Polymer 83 (2016) 260e282
  11. 11. 11 Microvascular System To overcome the difficulty of short supply of a healing agent in microcapsule-based self- healing concept, another approach similar to biological vascular system of many plants and animals are applied
  12. 12. 12 Microvascular System
  13. 13. 13 Reversible Cross-links  Cross-linking is an irreversible process, which gives superior mechanical properties  highly cross-linked materials have the disadvantage of brittleness and have the tendency to crack.  One approach to bring process ability to cross-linked polymers is the introduction of reversible cross-links in polymeric systems  However, reversible cross-linked system does not show self-repairing ability by its own. An external trigger such as thermal, photo, or chemical activation is needed to achieve reversibility, and thereby the self-healing ability.
  14. 14. 14 Diels–Alder (DA) and Retro-DA Reactions Major classes of thermally reversible polymers are made using Diels–Alder (DA) reactions
  15. 15. 15 Diels–Alder (DA) and Retro-DA Reactions
  16. 16. 16 Ionomers  Ionomers are a special class of polymeric materials that contain a hydrocarbon backbone and pendent acid groups  The ionic interactions present in ionomers usually involve electrostatic interactions between anions, such as carboxylates and sulfonates, and metal cations from Group 1A, Group 2A, or transitional metal cations
  17. 17. 17 In particular, the self-healing ability of poly(ethyleneco methacrylic acid) (EMAA)-based ionomers
  18. 18. 18 Supramolecular Polymers Recently, low molar mass monomers are assembled together by reversible noncovalent interactions to obtain polymer-like mechanical properties . As noncovalent interactions can be reversibly broken and can be under thermodynamic equilibrium, this special class of macromolecular materials, that is, the so-called supramolecular polymers show additional features compared to usual polymers Liu, Y.-L., Hsieh, C.-Y. and Chen, Y.-W. (2006) Polymer, 47, 2581–86.
  19. 19. 19 Photographs showing thermally reversible cross-linking behavior of PA-MI/TF polymers (PA-MI-1/TF polymers have lowest cross-link density and PA-MI-10/TF polymers have highest cross-link density). Polymer gel of PA-MI-1/TF in N, N-dimethylacetamide (DMAc): (a) 30 ◦C, (b), 160 ◦C and cross-linked PA-MI-1/TFin DMAc: (c) 30 ◦C, 5 h, insoluble and (d) 120 ◦C, 2 h, soluble. Cross-linked PA-MI-10/TF polymer in DMAc: (e) 30 ◦C, 5 h insoluble, (f) 120 ◦C, 5 h partially soluble, and (g) 160 ◦C, 5 h, soluble.
  20. 20. Applications 20
  21. 21. 21 self healing paint
  22. 22. 22 Next Generation Self-Healing Concrete: ♜Microbial Induced Calcium Carbonate Precipitation (MICCP) ♜Urease: (CO(NH2)2)  NH4 + + CO3 2– ♜Ca+ + cell  cell-Ca+ ♜cell-Ca+ + CO3 2–  cell-CaCO bacilli megaterium bacillus subtilus
  23. 23. 23 The composite material is made from hollow fibers filled with epoxy resin. When a hole or crack appears, the resin leaks out and seals the break and returns it to 80 to 90 percent of its original strength Self-Repairing Aircraft
  24. 24. 24
  25. 25. 25 When the concrete is mixed with bacteria (bacillus subtilus), the bacteria go into a dormant state, a lot like seeds. All the bacteria need is exposure to the air to activate their functions. Any cracks that should occur provide the necessary exposure. When the cracks form, bacteria very close proximity to the crack, starts precipitating calcite crystals. When a concrete structure is damaged and water starts to seep through the cracks that appear in the concrete, the spores of the bacteria germinate on contact with the water and nutrients. Having been activated, the bacteria start to feed on the calcium lactate nutrient. Such spores have extremely thick cell walls that enable them to remain intact for up to 200 years while waiting for a better environment to germinate. As the bacteria feeds oxygen is consumed and the soluble calcium lactate is converted to insoluble limestone. The limestone solidifies on the cracked surface, thereby sealing it up. Oxygen is an essential element in the process of corrosion of steel and when the bacterial activity has consumed it all it increases the durability of steel reinforced concrete constructions. Tests all show that bacteria embedded concrete has lower water and chloride permeability and higher strength regain than the surface application of bacteria. The last, but certainly not least, key component of the self-healing concrete formula is the bacteria themselves. The most promising bacteria to use for self- healing purposes are alkaliphilic (alkali- resistant) spore-forming bacteria. The bacteria, from the genus Bacillus, subtilus is adopted for present study. It is of great concern to the construction industry whether or not these bacteria are "smart" enough to know when their task is complete because of safety concerns. Bacillus Subtilus which is a soil bacterium (isolated from JNTUH soil) is harmless to humans as it is non-pathogenic microorganism. Chemistry of the Process Microorganisms (cell surface charge is negative) draw cations including Ca2+ from the environment to deposit on the cell surface. The following equations summarize the role of bacterial cell as a nucleation site 14 Ca 2+ + Cell --------> Cell- Ca 2+ Cell- Ca 2+ +CO 32-----> Cell-CaCO
  26. 26. 26 3 The bacteria can thus act as a nucleation site which facilitates in the precipitation of calcite which can eventually plug the pores and cracks in the concrete. This microbiologically induced calcium carbonate precipitation (MICCP) comprises of a series of complex biochemical reactions. As part of metabolism, B.Subtilus produces urease, which catalyses urea to produce CO 2 and ammonia, resulting in an increase of pH in the surroundings where ions Ca 2+ and CO 32- precipitate as CaCO 3 . These create calcium carbonate crystals that further expand and grow as the bacteria devour the calcium lactate food. The crystals expand until the entire gap is filled. In any place where standard concrete is currently being used, there is potential for the use of bacterial self- healing concrete instead. The advantage of having self- healing properties is that the perpetual and expected cracking that occurs in every concrete structure due to its brittle nature can be controlled, reduced, and repaired without a human work crew. Bacterial self-healing concrete also prevents the exposure of the internal reinforcements. This form of self-healing concrete was created to continuously heal any damage done on or in the concrete structure. It was made to extend the life span of a concrete structure of any size, shape, or project and to add extra protection to the steel reinforcements from the elements. With this process, money can be saved, structures will last far longer, and the concrete industry as a whole will be turning out a far more sustainable product, effectively reducing its CO2 contribution.
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