Plastics:
Plastics and Polymers
Plastics have changed the world.
Look around you, and chances are high that a variety of the things you can see are made of plastics. There are hard plastics and soft plastics, clear ones and colorful ones, and plastics that look like leather, wood, or metal. Developed during the twentieth century, plastics have changed the world.
All plastics were soft and moldable during their production - that's why they're called plastics. The Greek word plasticós means "to mold." You can form nearly any object out of plastics from bristles on toothbrushes to bulletproof vests to fibers for making textiles for clothes. Soon, tiny plastic projectiles may be used as carriers of vaccine, making it possible to swallow the vaccine instead of getting an injection!
1. Crude oil, the unprocessed oil that comes out of the ground, contains hundreds of different hydrocarbons, as well as small amounts of other materials. The job of an oil refinery is to separate these materials and also to break down (or "crack) large hydrocarbons into smaller ones.
2. A petrochemical plant receives refined oil containing the small monomers they need and creates polymers through chemical reactions.
3. A plastics factory buys the end products of a petrochemical plant - polymers in the form of resins - introduces additives to modify or obtain desirable properties, then molds or otherwise forms the final plastic products. 1. Crude oil, the unprocessed oil that comes out of the ground, contains hundreds of different hydrocarbons, as well as small amounts of other materials. The job of an oil refinery is to separate these materials and also to break down (or "crack) large hydrocarbons into smaller ones.
2. A petrochemical plant receives refined oil containing the small monomers they need and creates polymers through chemical reactions.
3. A plastics factory buys the end products of a petrochemical plant - polymers in the form of resins - introduces additives to modify or obtain desirable properties, then molds or otherwise forms the final plastic products. 1. Crude oil, the unprocessed oil that comes out of the ground, contains hundreds of different hydrocarbons, as well as small amounts of other materials. The job of an oil refinery is to separate these materials and also to break down (or "crack) large hydrocarbons into smaller ones.
How to make plastic: polymerization.
First, find a suitable molecule. One such molecule is the ethylene monomer, the starting point for a variety of plastics. Ethylene is a small hydrocarbon consisting of four hydrogen atoms and two carbon atoms.
Polymerization is often started by combining the monomers through the use of a catalyst - a substance that aids a chemical reaction without undergoing any permanent chemical change itself. During the chemical reaction, hundreds or thousands of monomers combine to form a polymer chain, and millions of polymer chains are formed at the same time. The mass of polymers that results is known as a resin. Resins are sold to plastics factories, usually in the form of powder, tiny granules, or pellets. The plastics manufacturer adds coloring agents and other additives that modify the properties of the material for the intended product. Finally, the resin is formed into the body of a cell phone, fibers for a sweater, or one of a myriad of other plastic products.
Polymers are everywhere
Plastics are polymers, but polymers don't have to be plastics. The way plastics are made is actually a way of imitating nature, which has created a huge number of polymers. Cellulose, the basic component of plant cell walls is a polymer, and so are all the proteins produced in your body and the proteins you eat. Another famous example of a polymer is DNA - the long molecule in the nuclei of your cells that carries all the genetic information about you.People have been using natural polymers, including silk, wool, cotton, wood, and leather for centuries. These products inspired chemists to try to create synthetic counterparts, which they have done with amazing success.
What are Plastics?
Plastics are synthetic materials, which means that they are artificial, or manufactured. Synthesis means that "something is put together," and synthetic materials are made of building blocks that are put together in factories.
The building blocks for making plastics are small organic molecules - molecules that contain carbon along with other substances. They generally come from oil (petroleum) or natural gas, but they can also come from other organic materials such as wood fibers, corn, or banana peels! Each of these small molecules is known as a monomer ("one part") because it's capable of joining with other monomers to form very long molecule chains called polymers ("many parts") during a chemical reaction called polymerization. To visualize this, think of a single paper clip as a monomer, and all the paper clips in a box chained together as a polymer.
Medium-Density Polyethylene: (MDPE).
1: Great resistance to chemicals.
2: Low moisture permeability.
3: Easy to process.
4: Low cost.
5: Recyclable.
6: Good impact strength in relation to its stiffness.
7: Used for chemical drums, carrier bags, flexible toys, car fuel tanks, cable insulation, furniture.
PS- Polystyrene:
1: Low density
2: Excellent fluidity.
3: Non abrasive.
4: Small with sphere of 0.5 diameter.
5: Its use: In a glass form the micro spheres are used as fillers for various applications to reduce weight.
Polyurethane Foam (PU):
1: Good chemical resistance.
2: Economic to produce.
3: Good strength.
4: Good dimensional stability.
5: No tooling costs.
6: Good accuracy of mould surface detail.
7: Easy to combine with other materials.
8: Excellent surface finish.
9: Recyclable.
10: Used for medical equipment, snow boards, furniture, windows, decorative mouldings.
11: Can be manufactured in many forms.
Polycarbonate (Polybutylene Tertphalate. PC/ PBT).
1: Low weight compared with steel.
2: Good colour retention.
3: UV stability.
4: Good impact strength.
5: Corrosion resistant.
6: Good electrical properties.
7: Chemical resistant.
8: High temperature performance.
9: Flame retardant.
10: Moulds quickly.
11: Weathers well.
12: Very good balance of chemical and mechanical properties.
13: Low temperature impact strength.
14: Heat resistance.
15: used for automotive fenders, car body panels, business equipment, cellphone casings, large structural parts.
Polyvinyl Chloride (PVC):
1: Easy to process.
2: Can be flexible or stiff.
3: High abrasion resistance.
4: Flame retardant.
5: Good weather resistance.
6: Good resistance to chemicals.
7: High clarity.
8: Used for cars, electrical engineering, credit cards, packaging, shoes, toys and guttering.
Polypropylene: (PP).
1: Flexible.
2:High clarity.
3: Can incorporate live hinge components.
4: Easy and versatile to process.
5: Excellent resistance to chemicals.
6:. Low density.
7: High heat resistance.
8: Low water absorption and permeability.
9: Recyclable.
10: Good range of translucency and colours.
11: Used for packaging, domestic accessories, stationery, garden furniture, toothpaste.
Polyurethane Resin (PU):
1: Excellent control.
2: Low tooling cost.
3: Allows careful control of colours and transparency.
4: Allows for casting in any thickness.
5: Perfect clarity.
6: Good adhesive properties.
7: Versatile forming process.
8: Used for furniture, interiors, sculpture, model making.
Polycarbonate (PC):
1: Exceptional toughness at low and high temperature.
2: Water clear transparency.
3: Unmatched impact resistance.
4: Good dimensional stability.
5: Flame resistance.
6: UV stable.
7: Easy to process.
8: Used for eye wear, water bottles, CDs, DVDs, kitchen containers, electrical appliances, glazing, cell phone casings, goggles, helmets, business equipment.
Polymethyl Methacrylate (PMMA):
1: low tooling costs.
2: Allows careful control of colour and transparency.
3: Allows for casting of any thickness.
4: Excellent optical clarity.
5: Good adhesion.
6: Outstanding UV resistance.
7: Vesratile froming process.
8: Used for furniture, interiors, sculpture, paper weights, model making.
Teflon Polytetrafluorethylene (PTFE):
1: Great chemical resistance..
2: Excellent mechanical strength.
3: Self lubricating.
4: Low friction coefficient.
5: Excellent electrical insulation properties.
6: Maintains its properties through a range of temperatures.
7: Good UV resistance.
8: Good weather resistance.
9: Transparent.
10: Used for wheels, surgical prosthetics, coating for cookware, washers, electrical shelving, cake tins, stain repellent for fabrics and textile products, tubing and piping in the semi-conductor industry, anti-corrosion surface coatings bearings.
Tyvek:
1: Super strong.
2: Lightweight.
3: Weather resistant.
4: Tear resistant.
5:Resistance to continuous folding and flexing.
6: Keep its porperties under a wide range of temperatures.
7: Unaffected by most chemicals.
8: Non toxic.
9: Chemically inert.
10: Approved for contact with food and cosmetics.
11: used for security envelopes, protective apparel, speciality packaging, roofing membranes, tags and labels, banners, maps, money, kites, reinforcement.
Polypropylene Sheet (PP):
1: Canbe heat welded.
2: Can be rivetedm stitched, embossed.
3: Can be ultrasonically welded.
4: Easy to rpocess.
5: Excellent resistance to chemicals.
6: Excellent ability to incorporate live hinge.
7: Recyclable.
8: Low water absorption and permeability to water vapor.
9: High print adhesion.
10: Tear resistant.
11: Cheap tooling.
12: Low density.
13: Used for furniture and packaging.
Fire retardant Polyvinylchloride Sheet (PVC):
1: Easy to process.
2: Low cost tooling.
3: Flexible.
4: Easy to colour.
5: Good transparency.
6: Good UV properties.
7: Easy for making one off prototypes.
8: Used for cable insulating sheaths, sewage pipes, table cloth, handle grips for bikes, toys, packaging , wallpaper.
Cellulose Acetate Sheet (CA):
1: Low heat and thermal conductivity.
2: Distinctive visual appearance.
3: Gloss finish.
4: Good range of visual effects.
5: Antistatic.
6: Good electrical insulation properties.
7: Self shining.
8: Excellent impact resistance.
9: Good transparency.
10: Versatile production.
11: Made from renewable source.
12: Used fro safety and sports goggles. frames for sun glasses, jewellery, watch straps, raincoats.
Polyvinyl Chloride Sheet ( PVC):
1: Easy to process.
2: Low cost tooling.
3: Flexible and versatile.
4: Easy to colour.
5: Good UV properties.
6: Easy to use for one off prototype.
7: Tough even at low temperatures.
8: Good transparency.
9: Used for chemical drums, carrier bags, toys, car fuel tanks, cable insulation, furniture ( i.e, Inflate).
Ethylene Vinyl Acetate ( EVA):
1: Good UV resitance.
2: Good chemical resistance.
3: Strong visual appeal.
4: Easy to colour.
5: Great flexibility.
6: Maintains physical properties at low temperatures,
7: Large choice of sizes.
8: Good strength to weight ratio.
9: Can be thermo-formed.
10: Used for packaging, exfoliating scrubs, bra-supports, cars.
Sublimation Coating:
A process that embeds a pattern into the surface of plastic. Because the dyes penetrate the surface of the plastic, the decoration is much more resistant to wear.
1: Good scratch resitance.
2: Good wear resistance.
3: High resolution.
4: Can be applied to variety of materials including non- plastics.
5: Easy to customise parts without retooling.
6: Can be applied to small or large production.
7: Used fro sporting goods, electronics, consumer appliances.
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