Recycled content can change molecular weight, additive balance, contamination level, color absorption, moisture behavior, and thermal history. Even when average composition meets a specification, batch variation may alter sag, forming range, wall distribution, odor, and mechanical performance.
Recycled percentage, source, number of heat histories, filtration, contamination, and batch identity should be linked to process data. A defect that follows a material blend but not the machine position points toward feedstock. Regrind from degraded or mixed materials should not be treated as equivalent to clean single-source scrap.
Acceptance criteria should reflect the end-use requirements and the capability of the forming process. Blending and traceability must be controlled. Heater recipes may accommodate a qualified range, but they cannot correct incompatible polymer contamination or severe degradation.