UN 38.3 Transport Testing Solvent Leakage Requirements
UN 38.3 limits lithium cell solvent leakage during transport through strict mass loss thresholds and zero visual electrolyte loss criteria across T.1-T.8 tests.
Crimp Gasket Stress Relaxation
Meaning
Mechanical behavior representing the gradual decrease in force exerted by a polymer seal under constant compression over time. In cylindrical lithium ion cells, monitoring crimp gasket stress relaxation is necessary to ensure long term hermetic sealing against electrolyte leakage. This phenomenon is highly temperature dependent and accelerated by exposure to elevated operating conditions, which can lead to premature battery degradation if the seal fails during long term field deployment.
Seal Integrity
Leakage prevention depends on the continuous radial pressure applied by the gasket against the metal can and cap. This seal integrity of the polymer degrades as the polymer chains rearrange under compression. If the force drops below a specific threshold, electrolyte solvent vapor escapes into the environment.
Polymer Selection
Material selection directly determines the rate at which stress decays over the operational lifespan of the battery. Choosing polymers with low susceptibility to deformation ensures that the stress relaxation remains minimal. Sourcing teams use these relaxation profiles to compare different elastomer suppliers.
Environmental Test
Accelerated aging at elevated temperatures evaluates the performance of different gasket materials over simulated multi year lifespans. The environmental test of the gasket ensures that the seal remains effective throughout the operating window of the cell. These evaluations are conducted before selecting a gasket material.