AMORPHOUS POLYMERS (e.g. PVC, Polystyrene, Acrylic, ABS, PPO, PC, Polyetherimide) have the following characteristics:

• a wide melting range
• low shrinkage after molding
• better impact and lower chemical resistance than crystalline polymers
• moderate heat resistance
• dimensional stability
• superior cosmetics of outer surfaces

CRYSTALLINE POLYMERS e.g. PPS, PBT (Valox), Polypropylene (PP) have the following characteristics:

• a sharply-defined melting point
• high shrinkage after molding
• low impact strength,-high heat resistance
• good fatigue endurance
• good lubricity; wear resistance
• good chemical resistance
• the ability to flow in thin-walled sections

Most plastics can be classified as either thermoplastic or thermoset, a label which describes the strength of the bonds between adjacent polymer chains within the structure. In thermoplastics, the polymer chains are only weakly bonded (van der Waals forces). The chains are free to slide past one another when sufficient thermal energy is supplied, making the plastic formable and recyclable. Westec Plastics uses thermoplastic polymers to create molded parts.

In thermosets, adjacent polymer chains form strong cross links. When heated, these cross links prevent the polymer chains from slipping past one another. As such, thermosets cannot be reflowed once they are cured (i.e. once the cross links form). Instead, thermosets can suffer chemical degradation (denaturing) if reheated excessively.