Resin - Plastic Resin Types

1.	Plastic Resin Types

Many different kinds of plastic resins are used for automotive parts depending upon their purposes. Plastic resin characteristics are also very different from one to another. It is important to know the material names and their chemical and mechanical characteristics.
Plastic resins can be roughly divided into two categories: thermoplastic resins and thermosetting resins.

Characteristics and Main Types of Thermoplastic Resins:

When heated, these resins become soft. If heated further, they will melt. When the temperature is reduced, they return to a solid state.

Resin Materials	Codes	Features
Polyethylene	PE	Good in cold resistant, electrical characteristic, and chemical-resistant properties. Impenetrable except air. Though inferior in strength, rigidity and thermal resistant properties, as density is increased, rigidity and thermal resistant property is improved.
Polypropylene	PP	The lightest in weight of all the resins. Used for large size parts like bumpers. Its strength, rigidity, and surface hardness are greater than those of Polyethylene (PE). It has a high thermal resistant temperature. Good in electric characteristics, anti-water and chemical-resistant properties. Strong in bending. Inferior in adhesiveness and weatherproof property.
Polyvinyl chloride	PVC	Through addition of plasticizer, it is possible to adjust its property from soft to hard. Good in electrical characteristics, chemical-resistant, and weather resistant properties. Inferior in anti-shock and anti-bending properties.
ABS resin	ABS	Good in mold forming, anti-shock property, and metal-plating properties. Easy secondary processing. Inferior in weatherproofing, heat resistant, and chemical resistant properties.
Acrylic resin	PMMA	Great in appearance. Used for lens for tail light lens. High transparent rate. Good in strength, weather proofing, and workability. Inferior in anti-shock, anti-solvent, heat-resistant properties.
Polyamide (Nylon)	PA	Used for structural member parts because of its high strength and tenacity. Good in self-lubricant, anti-wear, anti-solvent properties. Wide range of temperatures for use. High water absorption rate. A change of dimensions and or softening due to water absorption may cause troubles.
Polycarbonate	PC	Strong in shock absorption. Good in heat resistant and cold-resistant properties, electrical characteristics, self-digesting and weather proofing properties. Low fatigue strength. Stress cracks and solvent cracks may happen.

Characteristics and Main Types of Thermosetting Resins:

Once this type of resins is heated and, as the result, hardened, they are not softened again even if they are heated again.

Resin Materials	Codes	Features
Polyurethane	PUR	High elasticity. Good in anti-wear, anti-deterioration, anti-oil, and cold-resistant properties. Weak in alkali and hydrolytic dissociation easily takes place. Its hard foam is good for heat insulation and sound-insulation. As an adhesive, it can be hardened at room temperature and is strong.
Unsaturated polyester	UP	A typical material based on glass-based fiber for FRP. Good mold forming property. Cheaper than epoxy resin. Good in strength, rigidity, and electrical characteristics. Weak in alkali and hydrolytic dissociation easily takes place. Greatly shrinks when hardened. Insufficient heat-resistant property.
Glass fiber enhanced plastic	FRP	Resin (=matrix) is reinforced by fiber (=reinforcing material) to significantly increase the strength. A fiber reinforced plastic which offers a various superior features. There are a wide variety of properties available for both resin (unsaturated polyester resins, epoxy resin, phenol resin etc.) and reinforcing materials (glass fibers, carbon fiber, aramid fiber etc.) and the combinations can achieve many types of characteristics.