Amorphous thermoplastic polymers
In amorphous thermoplastic polymers, the molecule chains are completely chaotically arranged and tangled with each other like the threads of a cotton wool pad. This amorphous structure means that these materials cannot be subjected to loads above the glass transition point. This material group is further characterized by the following properties:
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mostly transparent or translucent
low tendency to creep
good dimensional stability
low tendency to warp
tendency to brittleness
low chemical resistance
sensitive to stress cracking
Amorphous plastics have a low tendency to warp and are consequently very suitable for use in housing components.
Semi-crystalline thermoplastics
The macromolecules of semi-crystalline thermoplastic polymers form a crystalline structure in some areas. Plastics with semi-crystalline structures are generally opaque, as the crystalline areas scatter the light. Due to the crystalline areas, the materials are extremely tough (strong intermolecular forces) and are capable of withstanding mechanical loads also above the glass transition temperature. The semi-crystalline thermoplastic polymers can be characterized by the following properties.
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translucent or opaque
good fatigue resistance
tendency to toughness
good chemical resistance
good sliding characteristics
wear resistant
glass transition
degree of crystallinity
Due to their tough-hard behaviour, semi-crystalline plastics are particularly suited for components subject to mechanical wear and for sliding materials.