Polyethylene terephthalate (PET) has excellent chemical resistance and barrier properties, good strength, rigidity, fatigue endurance, and abrasion resistance.
Typical Applications of Polyethylene terephthalate (PET)
Automotive
– mirror backs
– grille supports
– head lamp reflectors
– alternator housings
Electrical applications
– motor housings
– electrical connectors
– relays
– switches
– microwave oven interiors
Industrial applications
– furniture chair arms
– pump housings
– hand tools
– PET bottles and containers
Plastic PET Injection Molding Processing Conditions
| Conditions Name | Value |
|---|---|
| Drying | Drying is essential prior to molding. PETs are very sensitive to hydrolysis. Recommended drying conditions are 120°C–165°C [248°F–329°F] for 4 hours. The moisture content should be less than 0.02% |
| Melt Temperature | 265°C–280°C [509°F–536°F] for unfilled grades, 275°C–290°C [527°F–554°F] for glass reinforced grades. |
| Mold Temperature | 80°C–120°C [176°F–248°F] Preferred range: 100°C–110°C [212°F–230°F] |
| Material Injection Pressure | 30 MPa-130 MPa |
| Injection Speed | High speeds without causing embrittlement |
Runners and Gates of PET Injection Mold
All conventional types of gates can be used. Gates should be 50–100% of the part thickness.
Chemical and Physical Properties
PET is an aromatic polyester produced from the polymerization of either terephthalic acid (TPA) or dimethyl ester terephthalic acid (DMT) and ethylene glycol (EG). The glass transition is approximately 165°C [330°F] and the material crystallizes over a temperature range from 120°C–220°C [248°F–428°F].
PET is highly sensitive to moisture at high temperatures and exhibits excessive warpage when reinforced with glass fibers. The promotion of crystallinity is achieved through adding nucleating agents and crystal growth accelerators. Crystalline moldings exhibit high modulus, gloss, and heat distortion temperatures. Warpage is minimized by the addition of particulate fillers such as mica. When low mold temperatures are used, transparent moldings can be obtained with unfilled PETs.
