Examples of difficult-to-recycle materials and corresponding solutions
     Polyvinyl chloride

  PVC is a versatile and cost-effective material. It is used in a variety of packaging, such as hard film, soft film, seal, blister and display plate. On a global scale
  PVC accounts for about 5% of the plastic packaging market.
  PVC as a packaging material has some disadvantages. If the PET recycling contains PVC, it will cause quality problems. Even at a concentration of just 0.005%(by weight), PVC still produces PET-breaking acids that can make recycled PET brittle and yellow, compromising two of PET's most important properties: impact strength and transparency. PVC may be used in PET recycling streams in a number of ways, including (1) PVC bottles that are similar to PET bottles :(2) PVC seals, labels, and casings for PET bottles, and (3) PVC linings for bottle caps and inside bottle caps.
In many packaging applications, PVC has been increasingly replaced :PVC bottles are decreasing; Solutions based on conical gaskets made of extruded polyethylene foam or LDPE can replace PVC bottle cap linings; PE and PP labeling solutions are available. In many packaging applications unrelated to PET bottles, PVC is also being phased out: pallet-stretched packaging, LLDPE has replaced PVC:PET has been used as blister packaging. Companies such as Unilever and Marks&Spencer have clamped down on PVC in their packaging.
     (foamed) polystyrene or (E) PS
   Polystyrene (PS) accounts for about 3% of the plastic packaging market. The main applications of non-foamed PS are trays, cups and bottles, while foamed PS is mainly used in disposable food packaging, such as hot drink cups and clamshell packaging, food trays, for grade washing or to protect objects during transport.
   Today, the recovery rate of PS is very low. First, because many applications of PS packaging are related to food, the material is often contaminated. Secondly, due to the large volume of EPS (low density), it directly affects the collection and transportation costs.
   If the obstacles to efficient and economically viable PS collection, sorting, cleaning and recycling cannot be overcome, other packaging solutions may be considered. PET and PP are increasingly used in applications such as trays and yogurt cups. PS as freight protection has been replaced by Ecovative's mushroom derived Myco Foam. Companies such as Marks&Spencer are phasing PS out of their products and packaging. McDonald began phasing out its signature clamshell foam. More than 70 cities in the United States have begun to implement a ban on EPS food packaging, or even PS packaging, or have set an effective date for the ban, including Washington, DC, San Francisco, Oakland, Portland, Albany and Seattle.

      tag
   Labels play an important role in branding and information transmission. However, some types of labels may affect recycling, for example, full-color full-body labeling may lead to system misjudgments during the sorting process. If the paper label on the plastic container is not removed, the adhesive residue left behind during cleaning can contaminate the plastic material. In addition, some glues dissolve in water, so they cannot be removed from the container. These problems can be solved by choosing alternatives: plastic labels that cover no more than 40% of the surface of the container, and full-body sets with feet
Enough transparency and use of water-soluble glue.

         Bio-based, "biodegradable" and compostable plastics are different
   The term "bioplastic" is often used to refer broadly to plastics that are biobased, biodegradable, or both. A clear distinction must be made between the source of the material and post-use options. Also, as mentioned above, this report prioritizes "compostable" over "biodegradable."
   The term biobased describes the origin of a material that is derived wholly or partly from a biomass source.
    The term compostable describes post-use options for materials, i.e., a material that is suitable for a post-use pathway for domestic or industrial composting and meets formally defined criteria for the corresponding environment. The term biodegradable itself only describes a material that can biodegrade to a natural element with the help of microorganisms (without further specifying important criteria, such as the time of degradation in the corresponding environment).
     Bio-based plastics are not necessarily compostable, some bio-based plastics are designed for the technological cycle (bio-PET is recyclable) and some are designed for the biocycle (PLA is renewable and industrially compostable). Certain bio-based plastics, such as PLA and PHA, are technically both recyclable and industrially composted if the right infrastructure is in place.
    Similarly, not only bio-based materials are compostable. In addition to greenhouse gas-based plastics, certain fossil-based plastics, such as PBAT and BASF EcoFlex, can also be composted industrially