Thermoplastics are polymers that, when heated during processing, change from a solid state of aggregation to a liquid state: highly elastic or viscous, which makes it possible to mold them by various methods. 

These transitions are reversible and can be repeated many times, which makes it possible, in particular, to process household and industrial waste from thermoplastics into new products.

Thermoplastic polymers can have: a linear or branched structure, be amorphous (polystyrene, polymethyl methacrylate), semi-crystalline (polyethylene, polypropylene).

Linear (or branched) polymers, i.e. polymers whose macromolecules are chain sequences of repeating units. As a rule, linear polymers are relatively flexible and elastic, most of them are easily softened and melted.

In most cases, thermoplastics are amorphous polymers or have an amorphous-crystalline structure. As a rule, they are insoluble in water, soluble in naturally occurring organic solvents, resistant to acids and alkalis, and slightly hydroscopic.

Thermoplastics used without fillers are called resins. Thermoplastic polymer resins are widely used and we are constantly faced with their application. Thermoplastic resins are mostly non-reinforced, which means that the resin is molded into molds and does not have reinforcement to provide strength.

Examples of the most common use of thermoplastic resins and products made using them:

• Pentaerythritol – Water and Soda Bottles
• Polypropylene - Packaging containers
• Polycarbonate - Goggle lenses
• PBT - Children's toys
• Vinyl plastic - Window frames
• Polyethylene - Polythene bags
• PVC - Pipe Materials
• Polyethyleneimine - Aircraft armrests
• Nylon - Shoes

In the production of thermoplastic products, short discontinuous fibers are used as a reinforcing material. Glass cloth is the most common, but carbon cloth is also used. This enhances the mechanical properties of the product and is technically considered a fiber-reinforced composite material, but its strength is incomparable. Basically, for composites of this type, a reinforcing fiber with a length of ¼ or more is used.

Recently, thermoplastic resins have been used with continuous fiber to create composite products for structural purposes. There are a number of distinct advantages and disadvantages of thermoplastic composites versus thermoset composites.

• Advantages:
  First, most thermoplastic resins have higher impact resistance than thermoset composites. In some cases, this difference can be tenfold.

  Another major advantage of thermoplastic composites is their ability to change. Raw thermoplastic composites are solid at room temperature. When a reinforcing fiber is impregnated at a certain temperature and under pressure, a physical change occurs, rather than a chemical reaction, as is the case with thermoset composites.

  This allows you to modify thermoplastic composites. For example, a pultruded thermoplastic composite rod can be heated and reshaped to bend. But these operations are not possible with thermosetting composites. This ability also allows thermoplastic composites to be recycled when they have already reached the end of their service life (theoretically, practically not used yet)

• Flaws:
  The main disadvantage of thermoplastic composites is that thermoplastic resins are in nature in a solid state and it is much more difficult to impregnate the reinforcing fiber. The resin must be heated to its melting temperature, as impregnation and pressure cooling of the fiber will be required. This is quite complex and differs significantly from the traditional method of producing thermoset composites. It will require the use of special tools, equipment and technology, which will lead to additional high costs.

  Since the technology for the production of thermoplastic and thermoset composites is constantly evolving, and there is an application for each type, therefore, in the future, preference for one of the types will not be.

Materials:

• PEEK - Polyether Ether Ketone
• PEKK
• PPS - polyphenylene sulfide
• PEI - polyetherimide
• NYLON 12 - polyamide group
• PP (Polypropylene)
• TPU (Thermoplastic Polyurethane)
• PC - polycarbonate