A new research study conducted by PET packaging developer Plastic Technologies has found that exposing post-consumer bottles to ultraviolet (UV) light prior to recycling has a severe impact on the physical properties and visual attributes of next generation, recycled PET (rPET) bottles.
Intrinsic viscosity, yellowing and haze are some of the attributes that provide challenges when using rPET along with virgin material. rPET producers have engineered elaborate processes to minimise those characteristics in order to create material that provides the desired environmental attributes along with key visual and processing properties, Plastic Technologies said.
The bottles used in this study were not densely packed into large bales. Sunlight could easily penetrate through the several layers of bottle sidewalls, even reaching the bottles located at the bottom of the open crate.
Plastic Technologies vice president Dr Frank Schloss said: “What the average effect might be on an entire bale of bottles compared to what was seen in this study is a matter of debate. However one should consider all the potential causes of yellowing that can that limit the percentage of recycled PET that can be used. Exposure to UV radiation, whether it is from outside bale storage or possibly even exposure to fluorescent lighting in retail stores, should be considered as another contributor to rPET quality degradation.
“As an industry, we have focused on how package components affect next generation materials, but haven’t really considered storage impact. The more effort we make to remove all of the quality impediments, the greater the chance that our next generation materials will meet marketing, processing and environmental objectives.”
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