Plastics, Materials and Ceramics: Types, Processes and Applications

1. Plastic Classification and Applications

There are 3 types of plastic: thermoplastics, thermosetting plastics and elastomers.

Thermoplastics

Thermoplastics are the most common plastics. They are obtained from petroleum and consist of long chains of molecules that are weakly linked to each other. Examples include PVC, PS, PE, polymethacrylate, Teflon, Plexiglas and nylon, used in pipes and many other products.

Thermosetting Plastics

Thermosetting plastics are formed by a chemical reaction of molecules linked together strongly in both directions. Examples include polyurethane, phenolic resins and melamine, used in dishes, electrical components and laminates.

Elastomers

Elastomers are obtained through a process called vulcanization, which mixes natural rubber with sulfur. This gives them elasticity and resistance, and they are heated to around 160 °C. Examples include latex and Caucho (rubber).

2. Plastic Forming Techniques

There are 4 main forming techniques: extrusion, calendering, vacuum forming and molding.

• Extrusion: The plastic is melted in the form of granules, then pushed through a machine and shaped into a bar.
• Calendering: The resulting material from the extrusion cylinder is passed between rollers to produce thin sheets.
• Vacuum forming: Sheets of plastic are heated and shaped over a mold using suction, especially for thin plastic parts.
• Molding: Used to form finished pieces. Common methods include blow molding, injection molding and compression molding.

3. Animal Fibers

Wool comes from sheep. It is usually white or grey and is elastic.

Silk is a liquid substance secreted by some caterpillars, which solidifies in the air to form fine threads.

4. Natural Materials and Applications

Natural materials are obtained from rocks. They are the building blocks of nature and are used in the form of stone, such as marble and granite, extracted from quarries. They are used for covering floors and walls and for manufacturing decorative countertops.

5. Natural Aggregates and Binders

Sand and gravel are fragmented materials used as aggregates. They are combined with binders such as cement, lime or asphalt.

Common Construction Materials

• Clay: A material that resists traction and compression and is fireproof. When mixed with water it becomes pulp and hardens.
• Cement: Made from limestone and clay mixed and fired in a kiln. It becomes very resistant and is used in construction, bricks, blocks and pavements.
• Mortar: Formed from sand and cement. It acts as a binder for other materials.
• Concrete: A mixture of cement, sand and gravel that hardens with water. Used in construction of buildings, roads and pavements.

6. Glass

Glass is made by mixing sand with transparent quartz, soda and lime, and heating it to 1400 °C. The resulting molten mass is shaped by:

• Automatic blow molding: The molten glass is placed in a mold, air is blown in, and the mold is then injected with compressed air.
• Float glass forming: The molten glass is poured onto a bath of liquid metal in a basin, and then pushed along a conveyor of rollers.

7. Ceramics

Ceramics are obtained from clay and other materials. The clay is shaped into a mold, pressed, and then baked in a kiln at high temperature.

Types of Ceramics

• Coarse ceramics: Clay cooking pots, dishes and refractory items.
• Fine ceramics: Made from kaolin and other refined clays, used for porcelain and decorative items.