Analytical Verification of Polymer Migration Compliance across Industrial Container Shipments
Verify migration compliance using finished container single-sided cell tests, worst-case simulant conditions, and batch-matched documentation.
Flexitank Liners
Meaning
Bulk liquid containment membrane designed for installation inside standard twenty-foot intermodal shipping containers to transport non-hazardous liquid polyols and liquid polymer additives. Bladders convert dry freight containers into temporary liquid bulk tankers, reducing transport costs compared to rigid drums or tank containers. Using flexitank liners eliminates container return freight expenses because the bladders are single-use disposable packaging.
The term stops applying to rigid intermediate bulk containers or dedicated liquid tank trailers.
Structural Composition
Multilayer polyethylene film layers form the primary fluid retention barrier while an outer woven polypropylene jacket provides tensile strength against dynamic liquid sloshing. Multiple inner layers allow the container to conform to container walls without pinhole leaks. Valves installed at the bottom or top of the assembly permit rapid filling and discharge using standard liquid pumps.
Puncture Resistance
Dynamic forces during transport force liquid against container side walls, requiring heavy corrugated paper liners along container bulkheads. Foreign objects or protruding nails on container floors easily puncture single-layer bladders during transit. Modern flexitank liners utilize high-density resin blends with high dart drop impact strength to prevent tear propagation during ocean transit.
Container Payload
Maximizing liquid volume lowers freight costs per kilogram of liquid plasticizer or polyol. Oversized bladders exert excessive sidewall pressure on shipping containers, causing container wall bulging that violates railway and shipping line safety limits. Proper filling levels prevent liquid movement while avoiding structural overstressing of container frames.