Introduction to the types of plastic injection molding materials

Injection molding is the most widely used manufacturing process for plastic parts. It is not surprising, therefore, that there are many plastics available for injection molding, all available in pellet form. The range of moldable plastics includes highly durable polycarbonate and impact-resistant ABS.

This guide features 15 of the most popular plastic injection molding materials. Each injection molding material has its own unique advantages and is suitable for specific applications.

1.Acrylonitrile Butadiene Styrene (ABS)

ABS is a widely popular thermoplastic injection material with excellent toughness, elasticity, and impact resistance. Molded ABS parts include shock absorbers, housings, plastic canoes, musical instruments, medical devices, and toys. Because it can be molded or extruded, ABS is also widely used in 3D printing.

2.Polycarbonate (PC)

PC is a strong and durable engineering-grade thermoplastic. In addition to having desirable properties, it is easy to process and form. Manufacturers use PC pellets to make molded parts for computing, aerospace, and medical applications. Many smartphone cases and covers are also made with PC. PC can be blended with glass (PC-GF) to have excellent impact resistance and low moisture absorption.

3.ABS Polycarbonate (PC-ABS)

By combining ABS with PC, the desirable mechanical properties of PC and the formability of ABS can be obtained. PC-ABS molded parts include automotive parts such as glove boxes, TV frames, keyboards, and structural components.

4.Polypropylene (PP)

PP is a strong thermoplastic polymer with strong chemical resistance. It is the second most popular commodity plastic after polyethylene. Injection molding can be used to make PP products such as plastic furniture, pipes, fittings, living hinges, and food-safe containers.

5.Polystyrene (PS)

PS is a hydrocarbon polymer that is hard, brittle, and very inexpensive. Common applications of PS as an injection material include disposable cutlery, CD cases, test tubes, and microplates. PS can also be combined with polyphenylene ether (PS-PPE) to provide excellent heat resistance and dimensional stability.

6.Polyoxymethylene (POM)

POM is a high-performance engineering thermoplastic with high stiffness and excellent dimensional stability.

Common POM injection molded parts include handles, fasteners, gears, and automotive parts.

7.Nylon 66 (PA66)

Nylon 66 is one of the most widely used injection molded plastics in the nylon/polyamide family. It has high rigidity, mechanical strength, and heat and chemical resistance. Molded nylon 66 can be used in pipes, conveyor belts, automotive parts, cable ties, etc. Polyamides can also be blended with glass (PA-GF) for additional thermal stability.

8.Polymethyl methacrylate (acrylic acid) (PMMA)

PMMA, or acrylic acid, is a transparent thermoplastic that is sometimes used as a substitute for glass. Although brittle, acrylic acid is shatter-resistant. Molded PMMA can be used in lenses, windows, electronic housings, jewelry, etc. There are few better choices for transparent molded parts.

9.High-density polyethylene (HDPE)

HDPE is an ethylene-derived thermoplastic polymer with a very high strength-to-density ratio.

The material is recyclable and is often used to make plastic bottles and pipes for drinking or wastewater.

10.Low-density polyethylene (LDPE)

LDPE is a less crystalline polyethylene with slightly more branches than HDPE. This gives the injected material a lower tensile strength but higher elasticity. Molded LDPE is often used for packaging and containers as well as plastic computer parts.

11.Polyethylene terephthalate (PET)

PET is a thermoplastic polymer and a widely used polyester injection molding material. It is lightweight, strong, and impact resistant. Injection molded PET is widely used in recyclable plastic bottles, trays, blister packs, and other forms of packaging.

12.Polybutylene terephthalate (PBT)

PBT is an engineering thermoplastic and a type of polyester. It has high mechanical strength and good impact resistance. It is also solvent resistant. Injection molded PBT parts include electrical housings, connectors, and keyboard keycaps. The material is often treated with a phosphorus-based flame retardant system to make it fire resistant.

13.Polyphenylene sulfide (PPS)

PPS is a high-temperature thermoplastic polymer with excellent heat, abrasion, and chemical resistance. Due to its flame retardant properties, PPS is often used in molded electrical parts such as air conditioning components and kitchen appliances. It is also popular in industrial parts such as pumps, valves, and pipes.

14.Thermoplastic Elastomers (TPE)

TPE, or thermoplastic rubber, is a copolymer with both thermoplastic and elastomeric properties. They have excellent thermal properties and material stability. Injection molded TPEs are often used in automotive parts and medical components such as catheters.

15.Thermoplastic Vulcanizate (TPV)

TPV is a member of the TPE family that has particular advantages in injection molding. It is very durable and has excellent dimensional stability. Molded TPV is often used for waterproof seals and gaskets and is common in many industries.