Polypropylene (PP), also known as polypropene, is crystallized and rigid thermoplastic used widely in everyday objects like household products, battery cases, packaging trays, medical devices, etc. Also, it is the “addition polymer” made from the combination of propylene monomers.
What is Polypropylene
Polypropylene is a rigid, rugged, and crystalline thermoplastic produced from a propylene monomer. However, it is among the cheapest plastics available in the market today. Furthermore, PP belongs to the polyolefin family of polymers and is one of the top three widely used polymers today.
PP has a relatively slippery surface, making it possible to substitute for plastics in low friction applications. Although it is slippery at the molecular level, it does have a relatively high coefficient of friction. It also has the lowest density relative to other common plastics.
Characteristics of Polypropene
Some of the significant properties of polypropylene:
- Elasticity and Toughness
Toughness is the ability to deform without breaking. PP will act with elasticity over a specific range of deflection, but it will also experience plastic deformation early on in the process. Therefore, it is generally considered a “tough” material.
- Chemical Resistance
It is a good choice for containers of such liquids, such as first-aid products and cleaning agents, because diluted bases and acids don’t readily react with polypropylene.
- Fatigue Resistance
PP is still in its shape after a lot of bending, flexing, or torsion.
Polypropylene can be made transparent but naturally opaque in color when produced. Therefore, for applications where some transfer of light is essential, PP can use.
Polypropylene is very useful for electronic components because it has a very high resistance to electricity.
Different Types of Polypropene
Homopolymers and Copolymers are the two main types of polypropylene.
Block copolymers and random copolymers are categories of copolymers. The random copolymer has the co-monomer units arranged in irregular patterns. In contrast, block copolymer has co-monomer units arranged in blocks.
Homopolymer is like the default state of polypropylene material. Therefore, it is a general-purpose grade.
Material Properties of Polypropylene
It is beneficial to keep information about the properties of thermoplastic beforehand. The following are some fundamental properties of polypropylene:
- Melting Point of PP
Polypropylene’s melting point occurs at a range:
Copolymer: 135-159 °C
Homopolymer: 160-165 °C
- Chemical Resistance of PP
It has outstanding resistance to concentrated and diluted acids, bases, alcohols.
Polypropylene has good resistance to aldehydes, ketones, esters, aliphatic hydrocarbons.
Additionally, it has limited resistance to oxidizing agents, aromatic and halogenated hydrocarbons
- Density of Polypropylene
It is one of the lightest among all commodity plastics.
Homopolymer: 0.904-0.908 g/cm3
Impact Copolymer: 0.898-0.900 g/cm3
Random Copolymer: 0.904-0.908 g/cm3
It is high flammable material.
Advantages of Polypropene
- readily available and relatively inexpensive
- an excellent electrical insulator
- possesses good fatigue resistance
- has high flexural strength
- a relatively slippery surface
- has a good impact strength
- has good chemical resistance
- very resistant to absorbing moisture
Disadvantages of Polypropene
- has poor resistance to UV, scratches, and impact
- has poor resistance to chlorinated solvents
- highly flammable
- susceptible to oxidation
- challenging to paint
- has poor bonding properties
Polypropylene for Your Packaging Products
Overall, polypropylene is an excellent material. It is also often called the “steel” of the plastic industry because it can be modified to serve a particular purpose best. Polypropylene is an ideal choice for many products because it has a unique blend of qualities, unlike any other material.