Based on the composition found during sorting 2.5 kg samples were prepared for further
processing and analysis. To study the influence of bio-PE film, the PE film in the sorted film
product was replaced (25 and 50%) by bio-PE shopping bags. This to keep the other impurities
constant. The film product was milled to allow washing with 0.01 M NaOH solution and heavy
impurities were removed using flotation separation. Sample size before milling was 2.5 kg and
after milling, washing and flotation about 2 kg sample was collected (80%). During the procedure
both dirt and heavy plastics (like PET) were removed. All samples showed a highly similar weight
loss.
The film material is very fluffy and needs to be compacted before further processing. Industrial
methods are not available on a lab scale size, so film material was compacted in an oven to allow
some fusion of the film material. This could then be milled and added to processing equipment.
At this stage a reference sample was added containing 100% bio-PE shopping bags. Because of
the sample size it was decided to mix the sample using a batch kneader. Injection moulding was
used to produce uniform samples. After milling and mixing the plastic recyclate becomes grey
and no obvious impurities or colour variations can be seen in the samples