Industrial Plastic Materials and Manufacturing Processes

Plastics and Polymers

Polymers are synthetic materials created through chemical reactions by human intervention. Additives are included if you want to improve their properties. The main characteristics of plastics are corrosion resistance, thermal insulation, and acoustic and electrical insulation.

Raw Materials Used in Manufacture

In the early nineteenth century: Animal raw materials (silk, milk casein) and plant materials (latex and cellulose) were employed.

Up to approx. 1930: Coal tar was used.

Today: Oil and natural gas are used occasionally.

Common Plastic Additives

To obtain specific properties, certain additives should be added depending on what you look for: colorants, antistatic agents, conductive materials, or stabilizers.

Types of Plastic Materials

Thermoplastics

• Polycarbonate (PC): Glass replacement, safety helmets, police shields.
• Polyethylene (PET / PE): High density (bottles, boxes, pipes); Low density (bags, sleeping bags).
• Polypropylene (PP): Lawn bags, bottles.
• Polystyrene (PS): Rigid (films, car interiors); Expanded (white cork).
• PVC: Rigid (pipes, records, tanks); Plasticized (cables, hoses, toys).
• Teflon: Pipes, coatings.
• Methacrylate: Goggles, bathroom accessories.
• Polyamides: Fabrics, brushes.

Thermosets

• Phenolic resins: Telephones, switches.
• Urea resins: Plates, glasses.
• Melamine: Coating of boards, indoor furniture.
• Polyester Resins: Textile fibers, coatings.
• Epoxide resins: Adhesives.
• Polyurethane: Sponges, rubber gaskets.

Elastomers

These allow large plastic deformations without rupture and recover their original shape. Most are thermostable:

• Natural rubber: Aircraft wheels, mattresses.
• Synthetic rubber: Tires, pavements.
• Silicones: Adhesives, medical prostheses.
• Neoprene: Cable insulation, special clothing.
• Vulcanized rubber: Car wheels.

Plastic Forming Processes

Pressed: Inserts the granules into the mold, then pressure and heat are applied so the material flows through all the holes; it is then cooled and removed.

Injection: The granules are introduced into a container and heated; they are compressed by a piston which passes them through a nozzle to reach the mold.

Thermoforming: A sheet of plastic is placed into the mold, closed, and heated; once hot, a vacuum is applied.

Extrusion: Heat and pressure are applied to the plastic; once the mold is filled, hot air enters under pressure to expand the plastic and fit the mold.

Calendering: