CLASSIFICATION OF PLASTICS

AMORPH

Thermoplastic polymers can be divided into two categories, amorphous and semi-crystalline polymers, depending on their molecular structure.

Amorphous polymers are normally transparent and are suitable for making precision parts due to their high dimensional stability.

Semi-crystalline polymers are opaque, resilient and show high chemical resistance.

SEMI-CRYSTALLINE

Thermoplastic polymers can be classified also according to their temperature resistance.

Advanced engineering plastics can be used continuously at temperatures above 150 °C and have excellent thermal and mechanical properties.

High-performance thermoplastic polymers can be used continuously at temperatures ranging between 100 °C and 150 °C. They have good mechanical properties and good chemical resistance.

Standard thermoplastic polymers can be used continuously at temperatures below 100 °C.

POLYMER	ACRONYM	MAIN FEATURES
POLYIMIDE	PI	Depending on the type, they provide high strength with a low level of creep and good abrasion resistance for a continuous use at a temperature up to 300 °C, dimensional stability, electrical insulation, high purity, low outgassing. Suitable for mechanically and thermally stressed components. Inherently flame retardant.
POLYAMIDE-IMIDE	PAI	High mechanical resistance, low level of creep, high chemical resistance. Good abrasion resistance, low thermal expansion. Inherently flame retardant.
POLYETHERETHERKETONE	PEEK	This polymer has excellent properties, including a low level of creep and high elasticity modulus. Excellent tribological properties, especially abrasion resistance. Excellent resistance to various aggressive chemicals. FDA approved and physiologically inert. Inherently flame retardant.
POLYETHERKETONE	PEK	Improved properties compared to PEEK. Very good abrasion resistance. Suitable for high load dynamic applications. Excellent chemical resistance. Inherently flame retardant.
POLYETHERSULFONE	PES	Good electrical and dielectric properties. Suitable for food contact. Inherently flame retardant.
POLYPHENYLSULFONE	PPSU	Good impact strength, chemical resistance and hydrolysis resistance. Inherently flame retardant. Suitable for food contact.
POLYETHERIMIDE	PEI	Excellent mechanical and electrical properties. Inherently flame retardant. Suitable for food contact.
POLYSULFONE	PSU	High resistance, rigidity and hardness, low moisture absorption and excellent dimensional stability. Inherently flame retardant. Suitable for food contact.
POLYPHENYLENE SULFIDE	PPS	High chemical resistance, low level of creep, high dimensional stability due to low moisture absorption, high elasticity modulus. Inherently flame retardant.
POLYVINYLIDENE FLUORIDE	PVDF	High resistance, rigidity and hardness, low moisture absorption and excellent dimensional stability. Inherently flame retardant. Suitable for food contact.
POLYAMIDE FROM POLYTETRAMETHYLENEADIPAMIDE	PA46	Good thermal insulation. Particularly suitable for sliding and wearing parts, which are exposed to high temperatures. High abrasion resistance.
POLYAMIDE FROM HEXAMETHYLENEDIAMINE	PA66	Good rigidity, hardness, wear resistance, and dimensional stability. Good dynamic properties, FDA compliant types available. Suitable for parts exposed to higher mechanical and heat loads.
POLYETHYLENE TEREPHTHALATE	PET	Good tribological properties in moist or dry environments, high dimensional stability and low thermal expansion, low moisture absorption, good dielectric properties, good chemical resistance. FDA compliant.
POLYCARBONATE	PC	Amorphous, transparent material with excellent impact strength. Permanent operating temperature 120 °C, good mechanical strength, low level of creep and excellent dimensional stability. Suitable for food contact.
POLYBUTYLENE TEREPHTHALATE	PBT	High strength and low wear with high dimensional stability and good sliding properties. Extremely high rigidity with low thermal expansion coefficient due to glass fibre reinforcement.
POLYAMIDE FROM ε -CAPROLACTAM	PA6	Semi-crystalline thermoplastic with good damping properties, good impact strength and high resilience even at low temperatures, good wear resistance, especially against rough frictional surfaces.
POLYOXYMETHYLENE (POLYACETAL RESIN, POLYFORMALDEHYDE)	POM	Semi-crystalline POM-copolymer with good mechanical properties, low moisture absorption, good fatigue strength and rigidity, good dimensional stability, and possibility to obtain narrow tolerances. Good sliding properties. Suitable for food contact.
POLYAMIDE FROM DODECANOIC ACID	PA12	Excellent abrasion resistance and good chemical resistance. It is the polyamide with the lowest moisture absorption. Suitable for food contact.
POLYPHENYL ETHER	PPE	Excellent electrical insulation, easy to bond and weld, good mechanical properties and high resilience, resistant to hot water.
POLYMETHYL METHACRYLATE	PMMA	Transparent thermoplastic often used as an alternative to glass due to its light weight and shatter resistance. This is why is often called “acrylic glass”.
POLYPROPYLENE	PP	Excellent electrical insulation, extremely low moisture absorption, excellent chemical resistance, low density, easy to weld, can be FDA compliant.
POLYETHYLENE	PE	Excellent electrical insulation, extremely low moisture absorption, good tribological properties, good impact strength at low temperatures, easy to weld, resistant to various acids and cleaning agents, low density. Can be FDA compliant.
ACRYLONITRILE STYRENE ACRYLATE	ASA	This amorphous polymer belongs to the styrenics family. It can be considered halfway between ABS and PMMA (but it is not transparent). Intrinsic high resistance against UV rays (as PMMA) combined with good toughness in terms of impact strength (typical of ABS).
STYRENE ACRYLONITRILE	SAN	SAN is transparent, glossy, and scratch resistant. High chemical resistance, high rigidity and surface hardness.
ACRYLONITRILE-BUTADIENE-STYRENE COPOLYMER	ABS	Excellent electrical insulation, low moisture absorption, good damping properties, good bonding characteristics, high impact strength and rigidity. Resistant to diluted acids and cleaning agents.

ADDITIVATION

The properties of the materials can be modified for specific applications using additives.

REINFORCEMENT FIBRES

Glass fibre is used to increase mechanical strength and tensile strength in particular. Other properties, such as compression strength and dimensional stability, are also improved, thanks to a lower thermal expansion coefficient.

Carbon fibres can be used as an alternative to glass fibre to increase mechanical strength. A lower density allows for improved mechanical properties with a low weight. Carbon fibres also improve the friction coefficient and wear resistance.

FRICTION AND WEAR-REDUCING ADDITIVES

Graphite is pure carbon, which, in the form of a finely ground powder has high lubricating properties. Its uniform incorporation into a polymer matrix can lower the friction coefficient.

PTFE is a high temperature fluorinated polymer, typically used as an additive due to its sliding properties. In the presence of a dynamic load, PTFE-filled plastics develop a thin lubricant film on the opposite surface.

Molybdenum disulphide is used primarily as a nucleating agent and forms an even, fine crystalline structure. Even when added in small amounts, it increases abrasion resistance and reduces friction.

COLOURANTS

The addition of pigments and colourants to plastics allows for any colour to be produced (e.g. according to RAL, Pantone, etc.). However, the choice of pigments with high-temperature plastics is limited.

LIGHT STABILISATION

Environmental conditions or prolonged exposure to high temperatures can lead to discoloration and affect the mechanical properties of the material. The addition of UV or thermal stabilisers helps prevent such effects.

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