Evaluating Degradation Mechanisms in Post-Consumer Polyolefin Flake
Polyolefin degradation evaluation requires coupling multi-load melt flow testing and OIT analysis to quantify chain scission and restabilize flake lots.
NIR Flake Sorting
Meaning
A high-throughput sorting process uses near-infrared spectroscopy to separate polymer flakes by polymer type and color before compounding or pelletizing. This separation technology, referred to as nir flake sorting, scans crushed post-consumer plastic and uses air jets to redirect target materials into separate collector bins. It allows recycling facilities to achieve high levels of purity in recycled resin streams.
Spectroscopic Analysis
Near-infrared light illuminates the polymer flakes as they pass along a high-speed conveyor belt under a spectrometer sensor. Each polymer family exhibits a unique absorption spectrum because of differences in their chemical bonds. The sensor captures these spectral signatures in milliseconds and sends the data to a microprocessor that triggers air valves.
This rapid identification separates polyethylene from polypropylene and other materials.
Sorting Efficiency
The purity of the sorted output depends on flake size, moisture levels, and the feed rate of the material. Very small or damp flakes can stick together, which leads to sorting errors and cross-contamination. Optimizing the sorting process ensures that the target plastic stream reaches the purity levels required for high-performance moulding.
Economic Value
Mixed polymer scrap has low market value because it cannot be used for high-quality injection moulding applications. Upgrading this scrap via spectroscopic sorting creates high-purity single-resin streams that command a higher price. Moulders can confidently use these sorted flake streams to replace virgin resin in high-volume applications.