Vicat Softening Point

property

The temperature at which a flat-ended needle penetrates 1mm into a polymer specimen under specified load and heating rate, indicating the material's softening temperature.

In Simple Terms

Vicat softening point measures when a plastic begins to soften under heat. A needle is pressed into the material while temperature increases, and the point where it sinks 1mm deep is recorded. This helps determine a plastic's heat resistance for applications.

Why It Matters

Critical for resin selection in heat-exposed applications, processing temperature optimization, and quality control verification. Traders use Vicat values to match customer requirements and ensure consistent material performance across shipments.

Technical Details

Measured per ASTM D1525 or ISO 306 standards using 10N or 50N loads with 50°C/hour or 120°C/hour heating rates. Results vary significantly between test methods, so specifying conditions is essential. Higher molecular weight and crystallinity typically increase Vicat temperatures.

Real-World Examples

PVC resin grading

Rigid PVC with Vicat point of 80°C is suitable for pipes, while flexible PVC at 65°C works for wire insulation applications

Quality control verification

ABS resin lot shows Vicat of 98°C versus specification of 100°C minimum, triggering investigation into molecular weight or contamination issues

Application temperature limits

Polypropylene homopolymer with 150°C Vicat point confirms suitability for automotive under-hood components exposed to engine heat