how is plastic made? how are the raw materials obtained? what kind of organic stuff does it need?
steps used in manufactoring process (how are raw materials obtained, what needs to be grown and/or produced or manufactured to make the product, etc)
Include machines needed energy/heat required, labour required, chemicals needed waste produced during manufacturing, etc.
- 1 decade agoFavorite Answer
What are plastics?
It may surprise students to learn that gutta-percha, shellac, and the horns of animals—all naturally occurring substances—were used as plastic material before the first synthetic plastics were produced. Gutta-percha is derived from the sap of certain trees, and shellac is made from the secretions of a tiny scale insect. Before horn can be used, however, it must be "plasticized," or softened, by being boiled in water or soaked in an alkaline solution.
The first synthetic plastic was made from the plant material cellulose. In 1869, John Wesley Hyatt, an American printer and inventor, found that cellulose nitrate could be used as an inexpensive substitute for ivory. The mixture could be plasticized with the addition of camphor. Celluloid, as this new material was called, became the only plastic of commercial importance for 30 years. It was used for eyeglass frames, combs, billiard balls, shirt collars, buttons, dentures, and photographic film.
In 1951, two young research chemists for Phillips Petroleum Company in Bartlesville, Okla., made discoveries that revolutionized the plastics world. Today, the plastics they discovered—polypropylene and polyethylene—are used to produce the vast majority of the thousands of plastics products all over the world. (Read more about their discoveries in "Serendipity, Science & Discoveries" in this publication.)
The source for today’s wide variety of plastics? Petroleum.
Petroleum to Plastics
The technological road from oil field to finished plastic product has numerous fascinating side trips. Here’s the route taken in the petroleum-to-plastics process:
1. Petroleum is drilled and transported to a refinery.
2. Crude oil and natural gas are refined into ethane, propane, hundreds of other petrochemical products and, of course, fuel for your car.
3. Ethane and propane are "cracked" into ethylene and propylene, using high-temperature furnaces.
4. Catalyst is combined with ethylene or propylene in a reactor, resulting in "fluff," a powdered material (polymer) resembling laundry detergent.
5. Fluff is combined with additives in a continuous blender.
6. Polymer is fed to an extruder where it is melted.
7. Melted plastic is cooled then fed to a pelletizer that cuts the product into small pellets.
8. Pellets are shipped to customers.
9. Customers manufacture plastic products by using processes such as extrusion, injection molding, blow molding, etc.
Plastics Processing Methods
Extrusion Molding -- the main process used to form plastics. A heated plastic compound is forced continuously through a forming die made in the desired shape (like squeezing toothpaste from a tube, it produces a long, usually narrow, continuous product). The formed plastic cools under blown air or in a water bath and hardens on a moving belt. Rods, tubes, pipes, Slinkys®, and sheet and thin film (such as food wraps) are extruded then coiled or cut to desired lengths.
Plastic fibers also are made by an extrusion process. Liquid resin is squeezed through thousands of tiny holes called spinnerets to produce the fine threads from which plastic fabrics are woven.
Injection Molding -- is the second most widely used process to form plastics. The plastic compound, heated to a semifluid state, is squirted into a mold under great pressure and hardens quickly. The mold then opens and the part is released. This process can be repeated as many times as necessary and is particularly suited to mass production methods. Injection molding is used for a wide variety of plastic products, from small cups and toys to large objects weighing 30 pounds or more.
Blow Molding -- pressure is used to form hollow objects, such as the soda pop bottle or two-gallon milk bottle, in a direct or indirect method. In the direct blow-molding method, a partially shaped, heated plastic form is inserted into a mold. Air is blown into the form, forcing it to expand to the shape of the mold. In the indirect method, a plastic sheet or special shape is heated then clamped between a die and a cover. Air is forced between the plastic and the cover and presses the material into the shape of the die.
- SonjeLv 44 years ago