Establishing Multi-Party Supply Chain Dispute Protocols for Transit Moisture Ingress in Granular Polymers
Multi-party moisture disputes depend on ISO 15512 Method C baseline sampling at loading and container dew point tracking before silo transfer.
Container Rain
Meaning
Condensation phenomenon occurs on the internal surfaces of shipping enclosures due to temperature fluctuations during transit. In the polymer industry, container rain presents a severe risk to imported plastic resins by exposing packaged pellets to liquid water that can penetrate protective bags.
Condensation Mechanism
Air inside a sealed steel container holds moisture that condenses when the temperature drops below the dew point. As the metal roof cools rapidly at night, the warm, moist air inside rises and deposits liquid droplets on the ceiling. This water accumulates until it falls as container rain onto the cargo below.
Polymer Impact
Sacks of hygroscopic resin like polyamide or polycarbonate suffer from surface wetting and moisture absorption when subjected to this dripping water. High residual water in the pellets causes hydrolytic chain scission during the subsequent injection moulding process, leading to loss of mechanical properties in the finished part. Resin moulders must dry the affected material extensively to avoid defects like splay and brittleness.
Preventive Measure
Shippers deploy high-capacity desiccants and insulating liners to control the moisture levels inside the transport unit. Maintaining the internal relative humidity below forty percent prevents the air from reaching its dew point. These barrier systems isolate the resin bags from any water droplets that form on the steel walls.