Polycarbonate is the material people reach for when impact resistance is the headline requirement. It is genuinely exceptional in that respect — but specifying it without understanding its sensitivities leads to failures that look mysterious until you know what to look for.
What Polycarbonate Does Well
- Very high impact strength. PC is among the toughest transparent engineering thermoplastics, which is why it is used where a drop must not break the enclosure.
- Transparency. A clear shell lets operators see contents without opening the case, which matters for inspection, retail and rapid identification.
- Wide temperature range. It retains toughness at low temperatures better than many commodity polymers, and holds shape at elevated temperatures better than PP.
- Dimensional stability. Low moisture absorption and good creep resistance relative to some alternatives.
Where It Needs Care
| Sensitivity | What it means in service |
|---|---|
| Notch sensitivity | A sharp corner, deep scratch or poorly designed rib concentrates stress and can initiate cracking |
| Stress cracking | Certain oils, solvents and cleaning agents can cause crazing and cracking in stressed areas |
| Surface hardness | PC scratches more readily than many alternatives, which affects appearance and optical clarity |
| Processing sensitivity | Requires thorough drying before moulding; residual moisture degrades properties |
These are manageable, but they are design constraints rather than afterthoughts. Generous radii, avoidance of sharp internal corners, careful chemical exposure and correct cleaning agents all belong in the specification.
PC vs ABS vs PP
| Requirement | Polycarbonate | ABS | PP |
|---|---|---|---|
| Impact strength | Excellent | Good | Good, temperature dependent |
| Low-temperature toughness | Strong | Moderate | Weaker near freezing |
| Transparency | Available | Opaque | Translucent at best |
| Chemical resistance | Weak against some solvents | Moderate | Strong |
| Scratch resistance | Lower | Better | Moderate |
| Relative cost | Higher | Moderate | Lower |
When PC Is Worth the Premium
Specify polycarbonate when the consequence of a cracked shell is severe — expensive or dangerous contents, cold-climate deployment, or equipment that must remain visible without opening. For general tool transport, indoor storage and chemically aggressive environments, ABS or PP usually deliver better value and fewer sensitivities.