Flexible Packaging: Seal Strength & Tensile Modulus

Seal Integrity Analysis: ASTM F88 vs. ChP 4008

Heat seal strength is not just a number; it's about the "Failure Mode."

- Cohesive Failure: The sealant layer splits (Ideal).

- Adhesive Failure: The seal peels apart cleanly (Often indicates low temperature).

- Material Break: The film breaks before the seal (Seal is too strong).

The "300mm/min" Rule

ChP 2025 General Chapter 4008 explicitly mandates a test speed of 300 mm/min ± 30 mm/min. Many generic testers default to 100 mm/min or 500 mm/min, rendering the data invalid for NMPA audits. The KHT XLW Series features a "Compliance Lock" mode that automatically sets this speed.

Tensile Modulus (Stiffness)

For packaging lines running at high speeds, Secant Modulus (Stiffness) is critical. If the film is too stretchy (low modulus), it will deform during registration. The XLW-PC's software automatically calculates Modulus between 1% and 2% strain, providing actionable data for film formulation.