11 Types of Plastic Materials used for Molding (List)

There are 2 main types of plastic materials (or polymers) used for molding in manufacturing industries.

The simple classification of plastic molding materials are given below.

  • Thermoplastics
    • Polyethylene
    • Polypropylene (PP)
    • Polyvinyl chloride (PVC)
    • Polystyrene (PS)
    • Polytetrafluoroethylene (PTFE)
    • Acrylonitrile butadiene styrene (ABS plastic)
    • Polyamide (aka nylon)
    • Polyetheretherketone (PEEK)
    • Polycarbonates (PC)
    • Polyethersulfone (PES)
    • Polymethyl methacrylate (PMMA)
    • Acetals
  • Thermosetting plastic
    • Aminos
    • Phenolics
    • Polyurethanes
    • Polyesters
    • Epoxides

These two types of plastics are further classified into following plastic materials.

Well, this is just a simple list showing the types of plastics used in manufacturing.

But there are many other things like properties, uses and other important things that you should know about these plastic molding materials.

So let’s dive right into it.

Thermoplastics

Thermoplastics are the type of polymers that change their properties when they are heated and cooled.

When these polymers are heated, they can be formed into desired shape by applying heat and pressure. And these plastics solidify on cooling.

If the thermoplastics are again heated at the previous conditions, they can be reprocessed into new shapes by applying pressure on it.

Most of the plastics used nowadays are thermoplastics only.

The thermoplastics polymers contain long unlinked molecular chains that have high molecular weight.

When the thermoplastics are cooled below a certain temperature, they form a smooth surface along with a good structural strength.

Thermoplastics are such materials that can be melted and reused without any change in their properties.

Now let’s see each of the thermoplastic materials one by one.

#1) Polyethylene (PE)

Polyethylene is manufactured by polymerization of ethylene at very high pressures. During the polymerization of ethylene, the catalyst may or may not be used.

Polyethylene is flexible at room temperature and it starts softening at 95 °C temperature.

Examples of polyethylene are;

  • Bottles
  • Dustbins
  • Toys
  • Insulating materials
  • Tubes 
  • Packing materials
  • Storage tanks
  • Ducts, etc.

#2) Polypropylene (PP)

Polypropylene is the type of thermoplastic which has the least density as compared to other thermoplastics.

It also possesses strength, stiffness as well as it is chemical resistant.

Because of these reasons, polypropylene has many applications.

Examples of polypropylene are;

  • Crates
  • Car components
  • TV cabinets
  • Handles for tools
  • Small machine parts, etc

#3) Polyvinyl chloride (PVC)

Polyvinyl chloride is of two types.

  1. Plasticized PVC
  2. Unplasticized PVC (uPVC)

Plasticized PVC is flexible and it is used in wire covering, gloves, raincoats, floor tiles and toy balls.

Unplasticized PVC is a hard, tough, and strong material that is used in building industries which includes pipes, gutters, window frames, etc.

The credit card or debit card is also made up of unplasticized PVC.

#4) Polystyrene (PS)

Polystyrene is available in various grades from brittle to very tough.

The non pigmented grades of polystyrene is transparent and it is widely used in manufacturing of aircraft kits, vending cups, light fittings, disposable syringe, casing for ball point pens, etc.

The expanded form of polystyrene is used to make ceiling tiles, as well as it is used as a packing material and thermal insulating material.

#5) Polytetrafluoroethylene (PTFE)

Polytetrafluoroethylene is a type of thermoplastic that possesses extremely low coefficient of friction as well as it has good chemical resistance.

Polytetrafluoroethylene is widely used in areas such as insulating tapes, pumps, gaskets, diaphragms as well as non-stick coatings on utensils.

#6) Acrylonitrile butadiene styrene (ABS plastic)

Acrylonitrile butadiene styrene has high strength, stiffness and toughness. Because of this reason, ABS plastic is sometimes categorized as engineering plastics. 

ABS plastic has a disadvantage that it gets affected by chemicals like chlorinated solvents, esters, acids, ketones and alkalis.

Applications of Acrylonitrile butadiene styrene (ABS polymer) includes housing of TV sets, telephones, hair brush handles, refrigerator linings, etc.

#7) Polyamide (aka Nylon)

Polyamides (or nylon) is a type of engineering plastic that possesses strength, stiffness as well as toughness.

There are various types of nylons like nylon 6, nylon 11, nylon 66, etc. And these nylons are used in manufacturing of small gears, bushes, sprockets, bearings, etc.

Nylon can absorb moisture and this can affect its properties and dimensional stability.

For this reason, the glass reinforcement is done to reduce the problem of moisture absorption.

#8) Polyetheretherketone (PEEK)

Polyetheretherketone (also known as PEEK) is a new generation plastic which has a capacity to resist high temperature.

It is crystalline in nature and it is resistant to acids, alkalis and organic solvents.

Density of polyetheretherketone is 1300 kg/m3 and it is used for wire coating, electrical connections, etc.

#9) Polycarbonates (PC)

Polycarbonates is a type of engineering plastic material that has extreme toughness.

Polycarbonates are transparent and they have good resistance to temperature. But the only limitation is that it gets affected by alkaline solutions and hydrocarbon solvents.

Polycarbonates are used to manufacture baby feeding bottles, street lamp covers, camera parts, electrical components, compact discs, etc.

#10) Polyethersulfone (PES)

Polyethersulphone is a type of thermoplastic that can resist higher temperatures.

It is used for load bearing applications up to 180 °C.

This polymer is used in manufacturing of aircraft heating ducts, terminal blocks, tool handles, non-stick coatings, engine manifolds, etc.

#11) Polymethyl methacrylate (PMMA)

Polymethyl methacrylate is resistant to alkalis, detergents, dilute acids, as well as oils. But it is affected by solvents.

This plastic material shows the property of total internal reflection and hence it is used in advertising signs and some medical applications.

#12) Acetals

Acetals are the type of engineering plastic material that possesses strength, stiffness and toughness.

It is widely used in light engineering applications.

Its density is higher than that of nylon but the properties of acetals and nylons are somewhat similar to each other.

If we compare acetals and nylons, then the acetals show relatively low moisture absorption.

Thermosetting plastics

Thermosetting plastics are the synthetic materials that become strong on heating, but it cannot be remolded or reheated after their initial heat-forming.

Thermosetting plastics are exactly opposite to thermoplastics. Thermoplastics soften when they are heated, while the thermosetting plastic hardens on heating.

Thermoplastics can be heated, shaped and cooled as often as necessary without causing any chemical change. But the thermosetting plastics will burn when heated after the initial molding.

Thermosetting plastics have various advantages over thermoplastics.

The thermosetting plastics retain their strength and shape even when they are heated.

For this reason, the thermosetting plastics are used to manufacture permanent components.

Even when the temperature increases, this type of plastic does not become weak.

The vulcanized rubber which is used in manufacturing automobile tyres is the example of thermosetting plastic which burns (gets heated to a higher temperature) but it does not mold into a new shape.

Now let’s see each of the thermosetting plastic materials one by one.

#1) Aminos

Aminos age generally of two types, 

  1. Urea formaldehyde
  2. Melamine formaldehyde

Both these types are hard, rigid and they also have good abrasion resistance properties.

Urea formaldehyde is inexpensive but it shows moisture absorption that results in poor dimensional stability.

Urea formaldehyde is generally used for manufacturing of bottle caps, plugs, switches, handles of utensils, etc.

Melamine shows less moisture absorption and it is also chemically resistant.

Hence it is mainly used for tableware, electrical fittings and laminated worktops.

#2) Phenolics

Phenol formaldehyde (also known as Bakelite) is one of the oldest synthetic materials and it is a strong, hard, and brittle material which has excellent electrical resistance properties.

Bakelite is affected by alkalis and oxidizing agents.

It is widely used in electrical fittings, fan blades, handles of cookware, etc.

#3) Polyurethanes

Polyurethanes are the polymers that are available in three forms;

  1. Rigid foam
  2. Flexible foam
  3. Elastomers

The rigid foam is generally used for insulation material, flexible foam is used for cushion material and elastomers are used in tyres and shock absorbers.

#4) Polyesters

Polyester is also known as DIY type material which is used for manufacturing of small boats, tanks, car repair kits, chemical containers, etc.

#5) Epoxides

Epoxy resins are expensive than polyesters, but they have good toughness, less shrinkage and they also have low moisture absorption.

These materials operate in the temperature range of -25 °C to 150 °C.

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