Raw material selection :: Leomuovi Group


Plastics usually consist of basic polymers and additives, which give the plastic different properties.


Raw materials used to manufacture plastic – what is plastic made of?

Basic polymers are mixed with chemicals and other materials to create different plastic compounds. Additives like UV protection and fire-retardant chemicals, colourants, mineral and biodegradable fillers, hardeners, and softeners give the plastic its specific properties.

Plastics are generally divided into thermoplastics and thermosets according to their processing properties. The former can be remelted and recycled into new products, whereas the latter can be moulded only once. Thermoplastics are further differentiated by their molecular structure into amorphic and semi-crystalline plastics and show various mechanical properties. The amorphic group offers flexibility, and some of the amorphous polymers are transparent. On the other hand, semi-crystalline polymers have greater mechanical strength and stiffness.

Commodity plastics, engineering plastics, and speciality plastics

The polymer compounds can also be differentiated into three groups by application: commodity, engineering, and specialty. The first type comprises affordable polymers that are used in large amounts. They offer technical properties sufficient enough for applications in various consumer products.

Engineering plastics are used in more demanding products and have better technical properties than commodity plastics. They are also more expensive than commodity plastics for this reason.

Specialty plastics are advanced polymer compounds that resist high temperatures (over 250 C), chemicals, and extensive wear.


Thermosets are single-use plastics and cannot be remelted. The soft solid or liquid resin and the hardening agent are cured into the desired shape using heat. Products made from thermosets have good heat resistance and are mechanically strong. Many thermoset grades also have good electrical properties. One disadvantage of using thermosets is the slow manufacturing process and poorer opportunities to reuse or recycle the raw material as waste-to-energy.

Types of thermoset

Polyurethanes (PUR): Used in e.g., various kinds of insulation, workshops, and seats.

Unsaturated polyesters (UP): Commonly referred to as fiberglass and used in, e.g., boats, cars, containers, basins, pipes, ship, and train components, cast marble products, panels, profiles, and poles.

Epoxy (EP): Strong plastics that withstand high temperatures and chemicals. Epoxys are applied in, e.g., sports equipment, vehicle components, and the aviation and space industry.

Vinyl esters (VE): These polymers are more flexible than most other thermosets and have excellent chemical resistance. They are used in, e.g., industrial containers and pipes, chimneys, and wastewater processing pools.

Phenol formaldehydes (PF): PFs can withstand high temperatures. These grades are used in, e.g., the automotive and aviation industries.

Amino plastics (MF and UF): These polymer types are hard and stiff, with good impact resistance. Amino plastics also have good fire resistance properties.


Thermoplastics can be reused several times as they soften when heated and can be remoulded without affecting properties. This polymer group is divided into amorphous and semi-crystalline thermoplastics according to their molecular structure.

Amorphous thermoplastics

Amorphous plastics lack a sharp melting point and soften gradually when heated due to their randomly ordered molecular structure. As a result, amorphous grades have lower mould shrinkage and less tendency to deform than semi-crystalline plastics.

Semi-crystalline thermoplastics

This group of polymers is called semi-crystalline because most molecules are well-ordered with some random or amorphous areas in between. When exposed to high temperatures, these plastic grades keep solid for longer and abruptly transition to a liquid at their melting point. Semi-crystalline plastics do not soften when heated, so they are usually better at withstanding loads at a higher temperature than amorphous plastics. Semi-crystalline thermoplastics also have better fatigue strength and chemical resistance than amorphous plastics.

Types of thermoplastic

Acrylic, PMMA: These polymer types are used in, e.g., illuminated advertisements and aquariums as they are transparent. Acrylic is also used in paints.

Polyethylene, PE-LD: A commonly used plastic worldwide, e.g., plastic bags and wraps.

PE-HD: The classical representant of commodity plastics is used in, e.g., pipes, tubs, bottles, and toys..

Polypropylene, PP: This typical commodity plastic has excellent resistance against chemicals and is used for producing, e.g., films, fibers, ropes, and sheets.

Polystyrene, (PS): PS has good formability, colourability, and electrical insulation. It is used in, e.g., containers, toys, casings, and tubs.

Polyethylene terephthalate, PET: The most common application of this plastic is in the packaging industry, e.g., for soft drink bottles.

Polyvinyl chloride, PVC: Because of its excellent water resistance, PVC is the material for producing pipes, raincoats, and bags and is also used for electrical insulation.

Polyamide, PA: This is a very versatile plastic with applications in clothing, construction, or even—the automotive industries. The most well-known polyamide is nylon.

Polycarbonate, PC: This is an easily workable and impact-resistance plastic used to manufacture, e.g., sunglass lenses, CDs, riot shields, and safety glasses.

Polylactide, PLA: A biodegradable polymer manufactured from renewable raw materials used in, e.g., 3D printing, compost bags, food packaging, disposable tableware, and loose-fill packaging.

Polytetrafluoroethylene, PTFE: Its most prominent application is in various coatings, the most notable of which is the Teflon surface on frying pans.

Polyoxymethylene or polyacetal, POM: This is a classical engineering plastic used for manufacturing, e.g., screws and gearwheels.

Ethylene chlorotrifluoroethylene, ECTFE: The classical application of ECTFE is in, e.g., piping and container coatings.

Polyvinylidene fluoride, PVDF: This is an excellent plastic, e.g., bearings, piping, and microchips.

Acrylonitrile butadiene styrene, ABS: This polymer is ubiquitous as it is found in almost every domestic and office appliance.

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