Meaning
Quality metric measures the reduction in the molecular weight of a resin sample, typically polyester, following its conversion through an extruder or injection unit. Monitoring intrinsic viscosity loss helps ensure that the structural integrity of the final product remains within design requirements. Excessive drops signal that the material was too wet or processed at too high a temperature.
Molecular Shrinkage
Polymers are long chains that provide strength through entanglement. If intrinsic viscosity loss occurs during the melt phase, it means those chains have been cut into smaller pieces. A typical acceptable loss ranges from two to five percent depending on the final application.
Performance Decline
Containers made from resin with too much degradation may fail during impact tests or split under pressure. Because intrinsic viscosity loss is cumulative, each regrind cycle lowers the starting point of the next run. Testing identifies when a lot is unsuitable for heavy-duty storage.
Processing Standard
Samples are dissolved in solvent and timed as they pass through a capillary tube to check their health. Minimizing intrinsic viscosity loss requires rigorous drying of the raw pellets to eliminate hydrolytic breakdown. Reliable output depends on maintaining this value above the specified safety threshold.