One of the primary issues that recyclers face today is the challenge to produce high-quality recycled polyethylene terephthalate (rPET) with low b* (yellow) values. This study wanted to example the effect that repeated melting of PET resins has on color.
The trend seen shows (with some sample variability) that the yellowness, measured by b*, increases with each melt history. The other color attributes such as L* and a* are not nearly as affected by repeated melting. The haze level of rPET materials is also a critical attribute but as the data in this report shows, the haze levels of these resins are not appreciably affected by repeated. melting.
Read the full case study here.