Plastic is a commercial name for a group of materials that while being processed, can be pushed or formed into almost any desired shape and then retain that shape. Plastics can be cast, molded, or pressed into an unlimited variety of shapes. They are one of the most used materials on a volume basis in industrial and commercial life. Plastics are on par with metals, wood, and ceramics and are essential to the needs of virtually the entire spectrum of business. Plastics, properly applied, will perform functions at a cost that other materials cannot match.

Most plastics can be classified as either thermoplastic or thermosetting materials. Thermoplastic materials can be formed into desired shapes under heat and pressure and become solids on cooling. If they are subjected to the same conditions of heat and pressure, they can be reprocessed into new shapes. Thermosetting materials are like concrete, once processed and shaped, they cannot be reshaped. Today, the vast majority of plastics are thermoplastics.

Plastics are made up of polymers. Polymeric materials are characterized by long chains of repeated molecule units known as "mers". These long chains intertwine to form the bulk of the plastic. The ways in which the chains intertwine determine the plastic's macroscopic properties. Typically, the polymer chain orientations are random and give the plastic an amorphous structure. Amorphous plastics have good impact strength and toughness. Examples include acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile copolymer (SAN), polyvinyl chloride (PVC), polycarbonate (PC), and polystyrene (PS).

If instead the polymer chains take an orderly, densely packed arrangement, the plastic is said to be crystalline. Crystalline plastics share many properties with crystals, and typically will have lower elongation and flexibility than amorphous plastics, and better chemical resistance. Examples of crystalline plastics include acetal, polyamide (PA; nylon), polyethylene (PE), polypropylene (PP), polyester (PET, PBT), and polyphenylene sulfide (PPS). Advances in chemistry have made the distinction between crystalline and amorphous less clear, since some materials like nylon are formulated both as a crystalline material and as an amorphous material.

Thermoplastics and Thermosets

Material name Abbreviation Trade names Description Applications
Acetal POM Celcon, Delrin, Hostaform, Lucel Strong, rigid, excellent fatigue resistance, excellent creep resistance, chemical resistance, moisture resistance, naturally opaque white, low/medium cost Bearings, cams, gears, handles, plumbing components, rollers, rotors, slide guides, valves
Acrylic PMMA Diakon, Oroglas, Lucite, Plexiglas Rigid, brittle, scratch resistant, transparent, optical clarity, low/medium cost Display stands, knobs, lenses, light housings, panels, reflectors, signs, shelves, trays
Acrylonitrile Butadiene Styrene ABS Cycolac, Magnum, Novodur, Terluran Strong, flexible, low mold shrinkage (tight tolerances), chemical resistance, electroplating capability, naturally opaque, low/medium cost Automotive (consoles, panels, trim, vents), boxes, gauges, housings, inhalors, toys
Cellulose Acetate CA Dexel, Cellidor, Setilithe Tough, transparent, high cost Handles, eyeglass frames
Polyamide 6 (Nylon) PA6 Akulon, Ultramid, Grilon High strength, fatigue resistance, chemical resistance, low creep, low friction, almost opaque/white, medium/high cost Bearings, bushings, gears, rollers, wheels
Polyamide 6/6 (Nylon) PA6/6 Kopa, Zytel, Radilon High strength, fatigue resistance, chemical resistance, low creep, low friction, almost opaque/white, medium/high cost Handles, levers, small housings, zip ties
Polyamide 11+12 (Nylon) PA11+12 Rilsan, Grilamid High strength, fatigue resistance, chemical resistance, low creep, low friction, almost opaque to clear, very high cost Air filters, eyeglass frames, safety masks
Polycarbonate PC Calibre, Lexan, Makrolon Very tough, temperature resistance, dimensional stability, transparent, high cost Automotive (panels, lenses, consoles), bottles, containers, housings, light covers, reflectors, safety helmets and shields
Polyester - Thermoplastic PBT, PET Celanex, Crastin, Lupox, Rynite, Valox Rigid, heat resistance, chemical resistance, medium/high cost Automotive (filters, handles, pumps), bearings, cams, electrical components (connectors, sensors), gears, housings, rollers, switches, valves
Polyether Sulphone PES Victrex, Udel Tough, very high chemical resistance, clear, very high cost Valves
Polyetheretherketone PEEKEEK   Strong, thermal stability, chemical resistance, abrasion resistance, low moisture absorption Aircraft components, electrical connectors, pump impellers, seals
Polyetherimide PEI Ultem Heat resistance, flame resistance, transparent (amber color) Electrical components (connectors, boards, switches), covers, sheilds, surgical tools
Polyethylene - Low Density LDPE Alkathene, Escorene, Novex Lightweight, tough and flexible, excellent chemical resistance, natural waxy appearance, low cost Kitchenware, housings, covers, and containers
Polyethylene - High Density HDPE Eraclene, Hostalen, Stamylan Tough and stiff, excellent chemical resistance, natural waxy appearance, low cost Chair seats, housings, covers, and containers
Polyphenylene Oxide PPO Noryl, Thermocomp, Vamporan Tough, heat resistance, flame resistance, dimensional stability, low water absorption, electroplating capability, high cost Automotive (housings, panels), electrical components, housings, plumbing components
Polyphenylene Sulphide PPS Ryton, Fortron Very high strength, heat resistance, brown, very high cost Bearings, covers, fuel system components, guides, switches, and shields 
Polypropylene PP Novolen, Appryl, Escorene Lightweight, heat resistance, high chemical resistance, scratch resistance, natural waxy appearance, tough and stiff, low cost. Automotive (bumpers, covers, trim), bottles, caps, crates, handles, housings
Polystyrene - General purpose GPPS Lacqrene, Styron, Solarene Brittle, transparent, low cost Cosmetics packaging, pens
Polystyrene - High impact HIPS Polystyrol, Kostil, Polystar Impact strength, rigidity, toughness, dimensional stability, naturally translucent, low cost Electronic housings, food containers, toys
Polyvinyl Chloride - Plasticised PVC Welvic, Varlan Tough, flexible, flame resistance, transparent or opaque, low cost Electrical insulation, housewares, medical tubing, shoe soles, toys
Polyvinyl Chloride - Rigid UPVC Polycol, Trosiplast Tough, flexible, flame resistance, transparent or opaque, low cost Outdoor applications (drains, fittings, gutters)
Styrene Acrylonitrile SAN Luran, Arpylene, Starex Stiff, brittle, chemical resistance, heat resistance, hydrolytically stable, transparent, low cost Housewares, knobs, syringes
Thermoplastic Elastomer/Rubber TPE/R Hytrel, Santoprene, Sarlink Tough, flexible, high cost Bushings, electrical components, seals, washers

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