Polypropylene plastic is a rigid crystalline thermoplastic that is made from a propene (or propylene) monomer and used widely for a number of key plastic applications and products. It is popular in various industries, including automotive, consumer goods and furniture, textiles, healthcare, engineering and electrical appliances.
It has become so popular, in fact, that we would now find everyday life much harder without its existence, as its production touches on most, if not all aspects of modern living, from food packaging to medicine; transport to heavy industry. Advantages to using polypropylene include cheaper production costs, lower density, higher strength, aesthetically pleasing surface finishes and a highly versatile nature.
Taking a dual approach
The plastic comes in two main types – polypropylene homopolymer, which is a general-purpose grade used a lot in packaging, textiles, healthcare and electrical appliances. This type or polypropylene plastic has a higher strength-to-weight ratio, good chemical and impact resistance and is acceptable to be placed into direct contact with food. It is also stronger than the other form, polypropylene copolymer, which is a slightly softer plastic offering increased flexibility. Polypropylene copolymer offers excellent impact strength and stress crack resistance. It also has high processability, impact resistance and toughness, but it is not suitable for food contact use.
An extremely useful product
Together, then, these two types of polypropylene share an extensive list of beneficial properties and are suitable for numerous plastic applications that we come across in everyday domestic, consumer, commercial and industrial life. These include packaging for foodstuffs , tobacco, clothing and other consumer goods from films to rigid packaging and point of sale materials. These plastics offer good barrier properties, high strength and durability, attractive surface finishes and low production costs. The material is flexible and can be moulded into crates, bottles and pots, as well as plastic shrink-film overwraps, plastic food trays and wraps, plus packaging tabs and closures.
In other words, polypropylene represents a large proportion of the plastic packaging for the products we see, purchase and use on a daily basis around the world. Polypropylene plastics are also found elsewhere in translucent parts of consumer goods, such as furniture, electrical appliances, carpets, luggage and toys. They are commonly used inside cars and other vehicles too, for example in interior trims, dashboards, bumpers, battery cases and fender liners.
Moving across to the textiles industry, these versatile plastics are widely used in fibres and products such as tape strapping, plastic rope and twine, tote bags, sports garments and beach shoes. They are prized in this sector for their waterproofing properties, colour fastness and resilience to fading from the sun and damage from mould, rot and bacteria. The medical sector relies heavily on polypropylene plastics too for life-saving applications like disposable syringes, medical vials, diagnostic devices, petri dishes and intravenous bottles. In this case, the materials are sought-after for their resistance to wear and tear and fatigue, hygienic surface finishes, lightweight properties and flexibility for bespoke manufacturing.
Finally, many industries benefit from the toughness and high tensile strength of polypropylene homopolymers and copolymers in heavy-duty applications such as acid and chemical tanks, sheeting and pipes. They can withstand high temperatures, exposure to corrosion, oils and solvents and other hostile environments.
The final word…
Polypropylene plastics are straightforward and to produce using virtually all plastic processing methods currently available. These methods include, but are not limited to injection moulding, plastic extrusion and blow moulding. The various polypropylene plastics are fully recyclable and widely available, allowing them to grow into one of the most versatile, useful polymer products available today.