Polyolefin Non Intentionally Added Substances Identification Basics
Polyolefin non-intentionally added substances require chromatographic screening, Cramer toxicological tiering, and finished article migration verification.
Post-Consumer Recyclate Contaminants
Meaning
Unwanted substances found in plastics recovered from the waste stream interfere with the performance and safety of new products. These post-consumer recyclate contaminants include both physical debris like metal and paper as well as chemical residues from previous contents. Managing these impurities is the primary challenge when converting household waste into a high quality resin suitable for technical applications.
Chemical Migration
Volatile organic compounds often linger in the porous structure of recycled polyolefins. These post-consumer recyclate contaminants can transfer to the surface of a moulded part, causing unwanted odors or affecting the properties of packaged goods. In food contact applications, this contamination is strictly regulated to prevent the transfer of non-authorized chemicals into the food.
Processing Obstacle
Insoluble particles such as wood fibers or high melting point polymers can block the fine meshes in a melt filtration system. When post-consumer recyclate contaminants clog these screens, the pressure inside the extruder rises rapidly, necessitating frequent filter changes and reducing overall production efficiency. Failure to remove these solids can lead to structural weaknesses or visible flaws like gels and black specks in the final part.
Polymer Incompatibility
Trace amounts of different resin types can act as impurities that weaken the molecular structure of the primary material. For instance, small quantities of polyvinyl chloride or polyethylene terephthalate can cause the degradation of a polyethylene batch during processing. These post-consumer recyclate contaminants prevent the formation of a homogeneous melt, leading to reduced elongation at break and poor impact resistance in the finished article.