The Association of Plastic Recyclers
  • PP

    PP

PREFERRED

EVOH ≤ 6.0 wt% + PP-g-MAH tie layers with MAH > 0.1 wt% and EVOH:tie layers ratio ≤ 2

Ethylene Vinyl Alcohol copolymer (EVOH) is a common layer material used to increase the barrier properties of PP packaging. It is not separable in the recycling process and therefore will become part of the recycled PP. Maleated polyethylene (PE-g-MAH) tie layers are commonly used in combination with EVOH to improve the adhesion between PP and EVOH and have been shown to improve compatibility during the recycling process.

Fillers, pigments or additives with densities > 1.0 g/cm3 where density of blend with base resin is ≤ 0.97 g/cm3

Density is an important property and float-sink tanks are critical separation tools used by reclaimers. Many fillers, pigments and additives used with PP have higher densities and when incorporated into PP can increase the density of resulting PP blend causing it to sink in the float-sink tank. When a PP item sinks during reclamation, the item is lost as waste reducing yield, increasing cost, and thus will be categorized as non-recyclable. The density of an item can be calculated or measured via ASTM D792, ASTM D1505 or ISO 1183-1.

Workhorse additives that meet the PP blend density of ≤ 0.97 g/cm3

Most PP in a package contains some form of additives. The "workhorse" additives commonly used have not been shown to cause significant issues with the recycling process or further uses of the recycled PP. Commonly acceptable workhorse additives include:

  • Thermal stabilizers - These additives typically enhance the further processing of the polymer and are therefore preferred for recycling.
  • UV stabilizers – These additives typically enhance the further processing of the polymer and are therefore preferred for recycling
  • Nucleating agents
  • Antistatic agents
  • Lubricants
  • Fillers – note that many fillers are dense, so particular attention should be paid to the overall blend density
  • Pigments
  • Impact modifiers
  • Chemical blowing agents

Additive usage should be minimized to maintain the best performance of recycled PP for future uses.

Click below for commercially available Barriers, Coatings, Additives and Fillers that have achieved APR Design for Recyclability Recognition

APR Design® for Recyclability Recognitions

DETRIMENTAL

Optical brighteners

Optical brighteners are not removed in the recycling process and can create an unacceptable fluorescence for next uses of recycled PP. It is difficult to identify material with this negative effect until extremely late in the recycling process where a great deal of added cost has been imparted into a material of low value due to the additive.

EVOH > 6.0 wt% + PP-g-MAH tie layers with MAH > 0.1 wt% and EVOH:tie layers ratio ≤ 2

RENDERS NON -RECYCLABLEL

EVOH > 1% with any other tie layers

Fillers, pigments or additives with densities > 1.0 g/cm3 where density of blend with base resin is > 1.0 g/cm3 or < 51 wt% of the PP blend floats in water per screening test.

SCREENING TEST

REQUIRES TEST RESULTS

Fillers, pigments or additives with densities > 1.0 g/cm3 where density of blend with base resin is > 0.97 g/cm3 and < 1.0 g/cm3

SCREENING TEST

Workhorse additives where PP blend density is > 0.97 g/cm3

SCREENING TEST

Non-PP barrier materials other than EVOH

Testing must show that layers and coatings will either separate and be removed from the PP in the recycling process or have no adverse effects on the recycled PP in future uses. When used, their content should be minimized to the greatest extent possible. Some layers and coatings have been found compatible with PP or are easily separated in conventional recycling systems. Companies that are considering such barrier materials and are unsure of their compatibility with recycling should ask their suppliers to provide APR test results.

SCREENING TEST

DEFINITIVE TEST

Degradable additives (photo, oxo, or bio)

See APR Position Paper on Degradable Additives

APR Position Paper

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