Recycled Polyethylene Terephthalate Moisture Testing Methods
Accurate moisture testing below 50 ppm via Karl Fischer oven titration prevents hydrolytic intrinsic viscosity degradation in recycled PET during melt processing.
Recyclate Sourcing Specifications
Meaning
Procurement standards for recycled polymer resins define the acceptable limits of contamination, physical properties, and origin history of incoming waste streams. Establishing recyclate sourcing specifications ensures that the post-industrial or post-consumer material used in a molding operation yields consistent part quality. These guidelines are constrained by the availability of well-sorted waste streams and the sorting capabilities of the recycling facility.
Procurement Requirement
The specifications typically define the allowable percentage of regrind, melt flow rate range, density limits, and the maximum concentration of non-polymer contaminants like paper and metals. They also outline the moisture limits and pellet size distribution to ensure stable feeding and melting in the molding machine hopper. Setting these parameters helps the recycler understand the quality required and ensures the molder receives a raw material that can be processed without damaging the screw or barrel.
This consistency is essential for high-volume automated molding lines.
Moulding Protection
Out-of-specification recyclate can introduce foreign plastics with different melting points, leading to unmelted lumps or thermal degradation in the melt stream. These impurities can clog hot runner nozzles, damage gate inserts, and create weak spots in the molded parts. Having clear procurement limits protects the tooling from damage and reduces scrap rates.
Supplier Validation
Regular testing of incoming recyclate batches against the agreed specifications is necessary to ensure long-term consistency. Standardized tests, such as melt flow index and density measurements, provide quick verification of material consistency before the resin is released to the production floor. This proactive testing minimizes the risk of process drift during production runs.