Depolymerization Loss

Thermal Stability

Manufacturers measure this metric against the intrinsic viscosity of the virgin pellet supply. A baseline test compares the original polymer sample against a specimen subjected to simulated processing cycles in a capillary rheometer. Lower shear rates often produce a clearer result regarding degradation while high shear scenarios mask the chemical shifts by inducing mechanical alignment.

Moulders determine the safe operating window by tracking shifts in flow index across a series of residence tests.

Material Economics

Regrind streams show greater susceptibility to chain shortening compared to pristine virgin stock because the initial processing cycle already consumes a portion of the antioxidant package. The inclusion of recycled content demands stricter control over barrel heat zones to prevent the catastrophic failure of parts during mechanical load. Economically the loss represents the difference between the utility of a virgin grade and the diminished performance of an over-processed material batch.

Tooling Feedback

Processing engineers observe the physical evidence of chain scission through surface finish degradation and unexpected flash in areas far from the gate. Excessive gas evolution from the breakdown process displaces air in the tool and leaves deposits on the cavity surface that require frequent machine stops for cleaning. Corrective action involves adjusting the cooling rate or lowering the melt temperature until the viscosity remains stable throughout the cycle.

This performance degradation persists even if the part achieves the target dimensions for a specific mould run.