PC (Polycarbonate) is a resin used in plastics processing, classified into groups, classes, and grades for injection molding, extrusion, and blow molding. This page covers that classification system and a documented notch-sensitivity effect on impact toughness worth weighing in part design.
What is it?
PC (Polycarbonate) is classified under ASTM D3935 for unfilled and reinforced material suitable for injection molding, extrusion, and blow molding. Compositions are grouped (Group 01–06), then further classified into classes (Class 0–4) and grades (Grade 0–7).
Why should I use it?
- A single classification system covers unfilled and reinforced grades — see “What is it?” above.
- Its impact toughness under a sharp notch has been directly measured — see Limitations.
How it’s used
In Plastics & Polymers, PC (Polycarbonate) is used for injection-molded, extruded, and blow-molded parts.
Limitations — when it isn’t the right choice
- Sharp notches or stress concentrators in a part’s design are a real, measured weakness. A 2024 peer-reviewed study on two specific PC grades of differing molecular weight found that impact toughness rises sharply once the notch tip radius exceeds a critical threshold — measured at 0.15 mm for the higher-molecular-weight grade and 0.25 mm for the lower-molecular-weight grade. Below that threshold, impact toughness measured around 15 kJ/m² (brittle fracture); above it, toughness rose to roughly 70–120 kJ/m² (ductile fracture). This was documented for two specific tested grades; the exact critical radius should not be assumed identical across every commercial PC grade, including filled or reinforced compositions.