Polymer.new

POLYMERS & COMPOSITES :

POLYMERS & COMPOSITES Niranjani.V & Kavipriya.G Ist year, Department of ECE, Kingston Engineering College, Vellore. nira_teddy@yahoo.com, 9344009080 karthi_kavi@yahoo.com, 9894896387

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Polymer The word, polymer, implies that polymers are constructed from pieces (monomers) that can be easily connected into long chains (polymer). When you look at the above shapes, your mind should see that they could easily fit together. monomers

TYPES:

TYPES Smart polymers: Specially change according to their environment and their surroundings. Shape memory polymers (SMPs): Ability to return from a deformed state to their original shape induced by an external stimulus. Self-healing polymers: Ability to repair damage caused by mechanical usage over time. The inspiration comes from biological systems – ability to heal after being wounded.

Examples of polymer includes::

Examples of polymer includes: Natural polymers: Shellac Amber Natural rubber Cellulose Synthetic polymers: Bakelite Neoprene Nylon PVC Polyethylene Silicone

COMPOSITES:

COMPOSITES Made from two or more constituent materials with significantly different physical or chemical properties which remains separate and distinct within the finished structure. Examples: Glass-FRP Boron-FRP Carbon-FRP Concrete Cermets Dental composite

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NYLON A MAN MADE POLYMER

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Nylon is actually a “copolymer” because is it made from two monomers. When these two monomers are in the same beaker, they combine and give off a molecule of water. This is called a “dehydration” reaction because we are taking away ( de ) water ( hydra ). (regarding odour: amines smell like fish or worse. Adipic acid is odourless) Hexamethylene diamine methylene x 6 (hexa) amine x 2 (di) Tetramethylene dicarboxylic acid (adipic acid)

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Dehydration Reaction

Self-Healing structural composites:

Self-Healing structural composites

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Polymer Composites Research Group Iowa State University- USA Professor Michael Kessler Focused on self-healing structural composites. Natural degradation Their article describes a material with the ability to heal itself automatically, i.e. a self-healing material. Such materials are capable of resisting and slowing down the natural degradation process, thereby prolonging their useful service life.

HEALING MECHANISM:

HEALING MECHANISM Crack formation Crack ruptures the microcapsules, releasing the healing agent into the crack plane through capillary action. The healing agent contacts the catalyst triggering polymerization that bonds the crack faces closed.

HEALING SYSTEM: monomer liquid + Catalyst :

HEALING SYSTEM : monomer liquid + Catalyst Monomer liquid: Dicyclopentadiene (DCPD) - encapsulated in a polymer microsphere. Catalyst: Ruthenium based system called Grubbs’ catalyst - Dispersed within the matrix material.

Microcapsules Preparation:

Microcapsules Preparation The DCPD filled microcapsules are prepared by the in situ polymerization microencapsulation technique. The first step is to form an emulsion of the water-immiscible core material (DCPD) in an aqueous solution of anionic polymer under constant agitation. This is followed by the initiation of a polymerization process in the water phase to produce a capsule wall of urea-formaldehyde (UF).

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Thus the self-healing structural composites provides solution for long standing problems in material science such as, Material degradation and Microcracking induced failure .

New polymer that changes color instantly in response to external magnetic field.:

New polymer that changes color instantly in response to external magnetic field .

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Research team led by Yadong Yin Assistant professor of chemistry University of California Focused on colour changing polymer. The team has fabricated microscopic polymer beads that change colour instantly and reversibly when external magnetic fields acting upon them change orientation.

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Color change occurs with no change in the structure or intrinsic properties of the microspheres. What changes instead? Magnetic fields acting externally on the orientation of these microspheres. In this method, the color is tuned by changing the relative orientation of the periodic arrays in the microspheres by conveniently using external fields. Benefits? Instant action, contactless control and easy integration into electronic devices already in the market.” This is a smart and effective solution to solve the problems of previous works, which could not tune the photonic crystal structures.

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The color observed in the new materials is “structural color” Interference effects rather than pigments. Colorful feathers of many birds, butterfly wings and beetle shells Produced when microstructures in these objects are aligned in periodic arrays .

MECHANISM:

MECHANISM Magnetic iron oxide + resin (liquid phase) U.V radiation Dispersion Resin solid phase Mineral oil Solid microspheres Periodically arranged Spherical droplets Magnetic field U.V radiation

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A video showing Rotation of microspheres in a vertically changing external magnetic field. The color is switched between on (blue) and off states.

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The beads or “magnetochromatic microspheres” have excellent structural stability. They also are highly compatible with various types of dispersion media such as water, alcohol, hexane and even polymer solutions, allowing them to retain magnetically tunable colors in a variety of chemical environments. The new technology has a great potential for a wide range of photonic applications because the on/off switching of the diffraction color by the rotating photonic sphere is fast, greatly simplifying the pixel structures. Applications of the new material include display type units such as rewritable or reusable signage, posters, papers and labels, and other magnetically activated security features. The new material also can be used to make environmentally friendly pigments for paints and cosmetics, as well as ink materials for color printing.

Application Of Polymers & Composites:

Application Of Polymers & Composites POLYMERS: Children’s toys Aircraft Implantable devices Controlled drug delivery Photo resist materials used in Semiconductor manufacturing. Flexible Substrates in organic LED. COMPOSITES: Pavement in road ways Shower stalls Bathtubs Space craft Imitation granite Cultured marble sinks Countertops

CONCLUSION:

CONCLUSION The previous researches have paved a wider path into the world of polymers and composites. All the polymeric materials possess outstanding characteristics. Polymers are a part of our everyday life and without them around, this world would be very, very different, if not impossible to live in. So in order to meet these requirements scientists and technologists have to widen the research in the field of polymers and composites.

REFERENCES:

REFERENCES http://polycomp.mse.iastate.edu/index.html http://insciences.org/article.php?article_id=5695

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Thank You