Plastobitumen because it behaves like plastic
The most important types of thermoplastic and hardened plastic their properties and where you encounter them
The choice of material determines almost everything about a plastic product — how strong it is, where it can be used, how it should be processed, and what it costs. As a plastics maker you encounter a limited, but important selection of materials again and again, and knowing their basic properties enables you to understand why a recipe or a drawing points to exactly that material.
§Thermoplastic — the common types
| Material | Abbreviation | Properties. | Typical use |
|---|---|---|---|
| Polyethylene | PE | Tough chemical resistant food approved in several types | Bottles jerrycans foil pipes |
| Polypropylene | PP | Light, flexible, good fatigue strength (can be bent many times) | Hinge parts containers car components |
| PVC | PVC | Stiff or soft depending on additives, good electrical insulation | Window frames pipes cable insulation |
| Polyethylene terephthalate | PET | Clear, strong, suitable for recycling | Beverage bottles, foil |
| Acrylonitrile butadiene styrene | ABS | Impact-resistant, tough, good surface finish | Cabinets, Lego bricks, car parts |
| Polycarbonate | PC | Very impact-resistant, transparent, heat-resistant | Safety glasses cabinets building boards |
| Polyamide | PA (nylon) | Wear-resistant, low friction | Gears, guide rails, cords, and textiles |
§Thermoset plastic and composite resins
While thermoplastics can be melted and remelted again and again, thermoset hardens permanently in a chemical reaction and cannot be reformed. The most common thermoset resins in the composite field are unsaturated polyester, vinyl ester and epoxy. Unsaturated polyester is the cheapest and most widespread and is used in large quantities for boat hulls and tanks. Vinyl ester has better chemical and moisture resistance and is used where the product must withstand more, while epoxy has the best strength and adhesion but also the highest price, and is used in demanding structures such as wind turbine blades and aircraft components.
- 01Unsaturated polyester: cheap fast-curing used for boat hulls and standard composite.
- 02Vinyl ester: better chemical and moisture resistance than polyester.
- 03Epoxy: highest strength and adhesion but most expensive and requires longer curing time.
- 04Phenolic resin: highly heat and fire resistant, used in special industrial items.
Reinforcing fibres
Resin alone is brittle and has low strength — it is the reinforcing fiber that gives the composite its actual strength. Fiberglass is by far the most common choice and comes as loose mat or woven roving. Carbon fiber weighs significantly less at the same strength, but costs significantly more and is typically only used where the weight savings justify the price. Aramid fiber has unparalleled impact and penetration strength and is used in safety equipment and demanding structural parts.
“The right material for the task is half a good product before you have even touched a machine.”
— Professional rule of thumb on material choice.