PC/PBT (Polycarbonate + Polybutylene Terephthalate Blend): Applications, Advantages & Injection Molding Guide

PC/PBT is a blend of polycarbonate (PC) and polybutylene terephthalate (PBT), engineered to combine the rigidity and toughness of PC with the chemical resistance and processability of PBT. This high-performance thermoplastic alloy is well-suited for automotive, electrical, and industrial applications where strength, durability, and chemical resistance are essential.

What Is PC/PBT?
This blend leverages PC’s high impact strength and thermal resistance, while benefiting from PBT’s fast crystallization, chemical resistance, and dimensional stability. It’s especially valued in environments exposed to moisture, fuels, or industrial chemicals.

Key Applications of PC/PBT
PC/PBT materials are chosen for components subjected to mechanical stress, environmental exposure, and chemical interaction.

Automotive Applications
– Bumpers and exterior panels
– Under-the-hood parts (connectors, housings, fuse boxes)
– Mirror mounts and air intake components

Electrical & Electronics
– Power tool housings
– High-voltage connectors and switch housings
– Lighting fixtures and electrical enclosures

Industrial Equipment
– Pump casings, valve covers
– Business machine covers and fan blades
– Construction tool bodies

Advantages of PC/PBT
– High impact resistance even at low temperatures
– Excellent chemical resistance (better than PC alone)
– Stable dimensional accuracy and good stiffness
– Fast crystallization allows short cycle times
– Resistant to hydrolysis, fuels, oils, and detergents
– Improved weathering performance compared to unblended PC

Injection Molding Guidelines for PC/PBT
1. Drying Requirements
Moisture control is essential to avoid splay and brittleness.
– Target moisture: below 0.04%
– Drying temperature: 110–135 °C
– Drying time: At least 4 hours in a desiccant dryer

2. Melt and Mold Temperatures
– Melt temperature: 235–300 °C depending on filler content
– Mold temperature: 40–90 °C (higher for thicker or more critical parts)

3. Injection Pressure & Speed
– Pressure: Medium to high (600–1300 bar)
– Speed: Medium injection speed is preferred to reduce internal stress and preserve part finish

4. Gate Design
– All standard gates applicable; fan or edge gates preferred for large parts
– Gate diameter: should be optimized for rapid flow
– Hot runners can be used but must be temperature-controlled accurately

Common Defects & Prevention
– Flash or warping: Improve clamping force or reduce injection pressure
– Brittleness: Check moisture level and melt temperature
– Flow marks: Adjust injection speed and gate placement

Final Thoughts
PC/PBT is a robust material solution for manufacturers seeking high durability, chemical resistance, and thermal stability in a cost-efficient molding process. Its resilience in tough environments makes it ideal for applications in automotive, power tools, and electronics.
If you’re working on a project that demands tough, weather-resistant plastic components, PC/PBT may be the answer.
Reach out to our team to explore PC/PBT grade options tailored to your performance, processing, and budget requirements.